Ferromagnetic single-atom spin catalyst for boosting water splitting

Boosting selective CO2 reduction via strong spin-spin coupling on dual-atom spin-catalysts

Achieving high selectivity in electrochemical conversion of carbon dioxide (CO2) into valuable products remains a significant challenge. This study investigates the influence of spin states on dual-atom catalysts within two-dimensional metal-organic frameworks (2D-MOFs) and zero-dimensional molecular metal complexes (0D-MMCs), emphasizing their role in the selective electrocatalytic reduction of CO2. Utilizing first-principles calculations, we systematically evaluate dual-atom spin-catalysts (DASCs) TM2S4(NH)2(C6H4)2 0D-MMC and TM2S4(NH)2C4 2D-MOF for CO2 reduction reactions (CO2RR) across various spin states: antiferromagnetic (AFM), ferromagnetic (FM), and non-magnetic (NM). Our analysis confirms that, beyond successfully designing and screening highly active catalysts, the selectivity for various C1 products in CO2 reduction can be readily adjusted by DASCs via spin-spin coupling. Specifically, Mn2 and Fe2 2D-MOF DASCs with an AFM ground state are more inclined to produce formic acid, while their FM counterparts favor the formation of methane, surpassing formic acid among others. Additionally, we demonstrate that 0D-MMCs, as molecular units of 2D-MOFs, achieve comparable catalytic performance. Combining theoretical insights with machine learning highlights the crucial role of electronic and geometric descriptors in the catalytic performance. Our work establishes the correlation between spin-spin coupling and highly selective CO2 reduction in DASCs, offering an effective strategy for designing tunable and efficient electrocatalysts.

Asymmetric tacticity navigates the localized metal spin state for sustainable alkaline/sea water oxidation

Anodic oxygen evolution reaction (OER) that involves a spin-dependent singlet-to-triplet oxygen changeover largely restrains the water electrolysis efficiency for hydrogen production. However, the modulation of spin state is still challengeable for most OER catalysts, and there remains a debate on deciphering the active spin state in OER. Here, we pioneered an asymmetric Fe-incorporated NiPS3 tactic system to retune the metal localized spin for efficient OER electrocatalysis. It is unraveled that the synergistic effect of medium-spin FeIII site and P/S coordination can effectively boost OER activity and Cl resistance selectivity in alkaline/sea water. Resultantly, the Fe/NiPS3-based asymmetric electrodes exhibit low cell voltages of 1.50 volts/1.52 volts in alkaline/sea water at 10 milliamperes per square centimeter, together with a sustainable retention for 1000 hours. It also delivers the durable performance in anion exchange membrane water electrolyzers with a low operation voltage at 45°C. This research navigates the atomic localized spin state as the criterion in rationalizing efficient nonprecious alkaline/sea water oxidation electrocatalysts.

Bioinspired Protein-Mineralized Single-Atom Nanozymes for Tumor-Specific Cascade Therapy via Self-Amplifying Catalytic Synergy

Single-atom catalysts (SACs) are highly promising in biomedical applications due to their unmatched catalytic activity and atomic-level precision, yet their clinical translation is hindered by limited biocompatibility, instability, and lack of tumor targeting. Here, a universal, bioinspired strategy is proposed to construct flexible, biocompatible SACs by leveraging enzymatic protein scaffolds for mineralization of single-atom platinum (Pt). This protein-mineralized platform enables the fabrication of stable dual-functional nanozymes, exemplified by glucose oxidase-coordinated Pt (GOx-Pt), which simultaneously catalyze glucose oxidation and H₂O₂-to-•OH conversion, generating a self-amplifying cascade for reactive oxygen species (ROS) production. To ensure tumor specificity, the GOx-Pt nanozyme is encapsulated within a pH-responsive zeolitic imidazolate framework (ZIF-8), which remains stable under physiological conditions but disintegrates in mildly acidic tumor environments, enabling localized and selective therapeutic activation. This synergistic design not only enhances antitumor efficacy by inducing oxidative stress and glucose depletion but also minimizes systemic toxicity. The resulting ZIF-8@GOx-Pt system achieves robust catalytic stability, selective cytotoxicity, and significant tumor inhibition (53%) in vivo without discernible side effects. This work pioneers a versatile biomineralization approach for engineering SAC-based nanozymes with dual catalytic and tumor-responsive functions, offering a generalizable strategy for next-generation precision cancer therapeutics.

Magnetic-Field-Induced Spin Transition in Single-Atom Catalysts for Nitrate Electrolysis to Ammonia

Electrochemical nitrate reduction (NitRR) using single-atom catalysts (SACs) offers a promising pathway for sustainable ammonia production. Herein, we explore the use of external magnetic fields to regulate the spin state of Ru SACs supported on nitrogen-doped carbon (Ru-N-C), aiming to optimize their catalytic performance toward NitRR. Under magnetic field conditions, Ru-N-C exhibits a remarkable NH3 yield rate of ∼38 mg L-1 h-1 and a Faradaic efficiency of ∼95% over 200 h. Our spectroscopic and magnetic characterization demonstrates that the external magnetic field induces a spin transition to a high-spin state in Ru SACs/N-C. Theoretical analysis further suggests that the increased spin state of Ru shifts the density of states away from the Fermi level, weakening the adsorption affinity for *NH2. Economic analysis hints at cost effectiveness and scalability. Overall, this study demonstrates that magnetic-field-induced spin modulation effectively optimizes NitRR electrocatalysts.

Recognition Site Density Regulation of Schiff Base Organic Porous Polymers for Ultrasensitive and Specific Fluorescence Sensing toward Gaseous DCP

Due to the severe interference from analogues such as hydrochloric acid, it is of great significance to establish a highly reliable technique to enhance the discrimination ability toward diethyl chlorophosphate (DCP). Here, based on the electrophilicity of DCP, a series of zero-background fluorescence Schiff base materials with different densities of C═N bonds as recognition sites were designed and synthesized by modulating the chain length. It is found that the increase of the C═N bond density and the specific surface area could improve the collision efficiency with DCP, thereby improving the response speed. When the density of C═N bonds is 3.86 × 1021/cm3 and the specific surface area is 128.5 m2/g, DFDBA-POP demonstrated a more superior sensing performance toward the target analyte, including the ability to detect gaseous DCP, a rapid response (1 s), and superior selectivity even in the presence of 15 kinds of interferents including the very similar hydrochloric acid. Moreover, the practicality of DFDBA-POP was further verified by a DFDBA-POP solid-state sensor, which is capable of specifically identifying gaseous DCP. The present nonfluorescent Schiff base materials design and modulation strategy would open up a new gate for the rational design of high-performance fluorescent materials to detect and discriminate trace hazardous substances with similar structures and properties.

Tuning the Electronic Structure of Ni2P through Fe Doping to Trigger the Lattice-Oxygen-Mediated Oxygen Evolution Reaction

Developing cost-effective electrocatalysts for efficient seawater splitting requires a fundamental understanding of the oxygen evolution reaction (OER) mechanism. Herein, iron-doped nickel phosphide (Fe-Ni2P) is synthesized via a hydrothermal-impregnation-phosphidation strategy to investigate the role of Fe incorporation in modulating the electronic structure and OER pathways. Mechanistic investigations demonstrate that Fe doping triggers a shift from adsorbate evolution mechanism (AEM) to lattice oxygen-mediated (LOM) pathways, evidenced by pH-dependent kinetics, tetramethylammonium cation probing, and in situ electrochemical impedance spectroscopy (EIS). The LOM mechanism involves nonconcerted proton-electron transfers, facilitated by accelerated hydroxide adsorption (ks = 0.275 s-1) and dynamic surface reconstruction into amorphous NiOOH. The reduced activation energy (27.1 kJ mol-1) and lower charge-transfer resistance in Fe-Ni2P underscore its superior thermodynamics and kinetics. X-ray photoelectron spectroscopy and EIS further validate lattice oxygen activation and oxygen vacancy accumulation during the OER process. Electrochemical studies reveal that Fe-Ni2P exhibits a low overpotential of 220 mV at 10 mA cm-2 and remarkable stability through phosphate-mediated Cl- repulsion and dynamic surface reconstruction involving lattice oxygen activation in alkaline seawater. This work establishes Fe-induced electronic modulation as a critical strategy for activating LOM-dominated catalysis in transition metal phosphides.

Engineering Local Coordination and Electronic Structures of Dual-Atom Catalysts

Heterogeneous dual-atom catalysts (DACs), defined by atomically precise and isolated metal pairs on solid supports, have garnered significant interest in advancing catalytic processes and technologies aimed at achieving sustainable energy and chemical production. DACs present board opportunities for atomic-level structural and property engineering to enhance catalytic performance, which can effectively address the limitations of single-atom catalysts, including restricted active sites, spatial constraints, and the typically positive charge nature of supported single metal species. Despite the rapid progress in this field, the intricate relationship between local atomic environments and the catalytic behavior of dual-metal active sites remains insufficiently understood. This review highlights recent progress and major challenges in this field. We begin by discussing the local modulation of coordination and electronic structures in DACs and its impact on catalytic performance. Through specific case studies, we demonstrate the importance of optimizing the entire catalytic ensemble to achieve efficient, selective, and stable performance in both model and industrially relevant reactions. Additionally, we also outline future research directions, emphasizing the challenges and opportunities in synthesis, characterization, and practical applications, aiming to fully unlock the potential of these advanced catalysts.

Boosting the Selectivity in Oxygen Electrocatalysis Using Chiral Nanoparticles as Electron-Spin Filters

Controlling the electron spin of oxygen-containing intermediates is crucial for efficient oxygen electrocatalysis toward clean energy technologies such as fuel cells and water electrolysis. Current strategies for controlling the electron spins rely mainly on tuning the chemical structure of the oxygen electrocatalyst, which is often hardly achieved for metal and oxide electrocatalysts. The chiral-induced spin selectivity (CISS) effect, a significant discovery in chiral spintronics, represents an alternative approach for tuning the spin selectivity of oxygen electrocatalysts. Here we demonstrate the use of intrinsic chiral nanoparticles as electron-spin filters to tune the selectivity in oxygen electrocatalytic reactions. Chiral Au nanoparticles with a concave vortex cube structure were employed as the chiral substrate, exhibiting highly tunable optical chirality and intriguing CISS-like effect. As model systems, the catalytically active components such as Pt or Ni(OH)2 are overgrown onto chiral Au nanoparticles to construct the chiral hybrid electrocatalysts. Remarkably, both cases show chirality-dependent tunable activities over oxygen reduction/evolution reactions, respectively. The insights gained from this work not only shed light on the underlying mechanisms dictating the CISS-enhanced oxygen electrocatalysis by chiral nanoparticles but also provide an important knowledge framework that guides the rational design of chiral electrocatalysts toward oxygen electrocatalysis.

Unveiling the electrochemical nitrogen reduction reaction mechanism in heteroatom-decorated-Mo2CS2-MXene: the synergistic effect of single-atom Fe and heteroatom

Conversion of nitrogen (N2) to ammonia (NH3) is a significant process that occurs in environment and in the field of chemistry, but the traditional NH3 synthesis method requires high energy and pollutes the environment. In this work, the charge, orbital and spin order of the single-atom Fe loaded on heteroatom (X) doped-Mo2CS2 (X = B, N, O, F, P and Se) and its synergistic effect on electrochemical nitrogen reduction reaction (eNRR) were investigated using well-defined density functional theory (DFT) calculations. Results revealed that the X-element modified the charge loss capability of Fe atoms and thereby introduced a net spin through heteroatom doping, resulting in the magnetic moment modulation of Fe. Upon incorporating N2 molecule vertically into Fe@P-doped-Mo2CS2, the strongest eNRR performance and activation ability for the NN were achieved. This was due to the 1πu antibonding orbitals being filled with extra charges from Fe atoms and the σ2s bonding orbitals experiencing a splitting phenomenon as a result of net spin injection from P atoms. Thus, this work provides rational design principles for the development of non-noble metal eNRR electrocatalysts by ingeniously manipulating their spin order and local environments.

Enhancing C─C Bond Cleavage of Glycerol Electrooxidation Through Spin-Selective Electron Donation in Pd-PdS2-Cox Heterostructural Nanosheets

As a 4d transition metal, the spin state of Pd is extremely difficult to directly regulate for the optimized d orbital states owing to the strong spin-orbit coupling effect and further extended d orbital. Herein, we devise a "spin-selective electron donation" strategy to tune specific d orbital electrons of Pd inspired by the Dewar-Chatt-Duncanson model theory. Co-S-Pd bridges with different spin-states of CoIII have been constructed in a series of Pd-PdS2-Cox HNSs with tunable Co content. Experiments and theoretical calculations indicate that low-spin CoIII (t2g 6eg 0) with fully occupied t2g orbitals and emptyd z 2 $d_{{z^2}}$ orbitals can accurately alter thed z 2 $d_{{z^2}}$ electron of Pd by σ-donation via the Co-S-Pd bridge. In contrast, the unfilled dxy orbital of high-spin CoIII (t2g 5eg 1) is essential for controlling the dxy electron of Pd via π-donation. Benefiting fromd z 2 $d_{{z^2}}$ state optimization by σ-donation, Pd-PdS2-Co4.0 delivers superior performance toward various bio-alcohols (ethanol, ethylene glycol, and glycerol) with enhanced C─C bond cleavage. Furthermore, coupling the glycerol oxidation reaction with the CO2 reduction reaction (GOR||CO2RR), the electricity consumption of GOR||CO2RR drops 46.4% compared to the state-of-art system (OER||CO2RR). Moreover, anodic Faraday efficiency (FE) of formic acid can be attainable at more than 90% at low voltage regions.

Role of Site-Specific Iron in Fe-Doped Nickel Hydroxide Toward Water Oxidation Revealed by Spatially Resolved Imaging at the Single-Particle Level

Water electrolysis driven by renewable electricity is limited by the slow-kinetic oxygen evolution reaction (OER). NiFe-based hydroxides are considered promising non-noble electrocatalysts toward the OER but require profound insight into the role of site-specific iron incorporation. Herein, we determined the critical role of edge sites on single-crystalline NiFe-based hydroxide toward the OER using spatially resolved in situ single-particle imaging techniques. The potential-driven incorporation of Fe into the specific edge or plane sites was achieved on two-dimensional (2D) Ni layer double hydroxide (LDH) single crystals. The spatially resolved scanning electrochemical cell microscopy imaging illustrated that Fe-doped edge sites dominated the activity of the OER rather than Fe-doped plane sites. In situ Raman spectroscopy imaging of single particles was used to monitor the evolution of edge and plane sites, revealing that the incorporation of Fe impeded the oxidation of Ni. Moreover, spatially resolved 18O-isotope-labeling experiments demonstrated that Fe doping hindered the oxygen exchange between Ni LDH and the electrolyte, inducing the switch of partial active sites from Ni to Fe. Combined with theoretical calculations, the Fe-Obridge-Ni sites contributed to the enhanced OER activity on Ni LDH with Fe doping at the edge, whereas the Ohollow (NiNiFe) sites induced by the infiltration of Fe into the plane were detrimental to the OER performance. This work provides direct spectroscopic evidence for understanding the specific sites at the single-particle level and guides the rational design of optimal electrocatalysts.

Spin-controlled electrocatalysis: an out-of-the-box strategy for the advancement of electrochemical water splitting

Spin-polarized catalysts have garnered significant interest in electrocatalysis, namely in the electrocatalytic oxidation of water, which has very sluggish kinetics due to its high overpotential. After the groundbreaking discovery that the electron's spin employing the chiral-induced spin selectivity (CISS) effect can control the kinetics of the oxygen evolution reaction (OER), numerous studies have been carried out to demonstrate the impact of electron's spin on reducing the overpotential of the OER. Apart from CISS, various magnetic materials have been explored as OER catalysts, and the outcomes are found to be very promising for the development of spin-based OER catalyst materials. This review highlights the remarkable journey of the evolution of the spin-polarized catalyst, starting from chiral materials to magnetic materials, which has happened in the last decade and its contribution toward the enhancement of OER kinetics, which is a very essential process for the advancement of renewable energy technologies.

Data-driven discovery of biaxially strained single atoms array for hydrogen production

The structure-performance relationship for single atom catalysts has remained unclear due to the averaged coordination information obtained from most single-atom catalysts. Periodic array of single atoms may provide a platform to tackle this inaccuracy. Here, we develop a data-driven approach by incorporating high-throughput density functional theory computations and machine learning to screen candidates based on a library of 1248 sites from single atoms array anchored on biaxial-strained transition metal dichalcogenides. Our screening results in Au atom anchored on biaxial-strained MoSe2 surface via Au-Se3 bonds. Machine learning analysis identifies four key structural features by classifying the ΔGH* data. We show that the average band center of the adsorption sites can be a predictor for hydrogen adsorption energy. This prediction is validated by experiments which show single-atom Au array anchored on biaxial-strained MoSe2 archives 1000 hour-stability at 800 mA cm-2 towards acidic hydrogen evolution. Moreover, active hotspot consisting of Au atoms array and the neighboring Se atoms is unraveled for enhanced activity.

Coordination Anions Dimensionality-Engineered Dual-Atom Catalysts for Enhanced Fenton-Like Reactions: 3D Coordination Induced Spin-State Transition

Dual-atom catalysts (DACs) have shown significant application potential in Fenton-like reactions. However, effectively modulating their electronic structure and fully understanding the mechanisms driving their high catalytic activity remain challenging. Herein, we propose a coordination anions dimensionality engineering strategy to synthesize biomass-derived dual-atom FeCo-N4O1C catalysts, in which Fe and Co atoms are bridged by two-dimensional planar N atoms and a three-dimensional (3D) axial O atom. Experimental data and theoretical calculations reveal that the 3D coordination structure of FeCo-N4O1C induces the spin state of Fe undergo a transition from a low spin state to an intermediate spin state compared with single-atom Fe-N4O1C, resulting in moderate adsorption and desorption of intermediates, thus reducing the energy barriers for generating more singlet oxygen and high-valent cobalt-oxo species during peroxymonosulfate activation. The electron transfer from Co atoms to neighboring Fe atoms through N atoms and 3D axial O atoms can effectively prevent the poisoning of active species. Benefiting from the 3D coordination structure and the synergistic effects of multiple active sites, the catalyst-dose normalized reaction rate constant reaches 14.5 L min-1 g-1 under low peroxymonosulfate concentrations─an improvement of 1 ∼ 2 orders of magnitude over most reported catalysts. The practical applicability of FeCo-N4O1C is demonstrated through nearly 100% pollutant removal during 7 days of continuous operation in a membrane filtration system. This study provides deep insights into the relationship between electronic structure and catalytic performance through spin-state regulation of DACs, and introduces a promising approach for large-scale synthesis of low-cost, highly efficient DACs for Fenton-like reactions.

Deactivation Mechanism and Mitigation Strategies of Single-Atom Site Electrocatalysts

Single-atom site electrocatalysts (SACs), with maximum atom efficiency, fine-tuned coordination structure, and exceptional reactivity toward catalysis, energy, and environmental purification, have become the emerging frontier in recent decade. Along with significant breakthroughs in activity and selectivity, the limited stability and durability of SACs are often underemphasized, posing a grand challenge in meeting the practical requirements. One pivotal obstacle to the construction of highly stable SACs is the heavy reliance on empirical rather than rational design methods. A comprehensive review is urgently needed to offer a concise overview of the recent progress in SACs stability/durability, encompassing both deactivation mechanism and mitigation strategies. Herein, this review first critically summarizes the SACs degradation mechanism and induction factors at the atomic-, meso- and nanoscale, mainly based on but not limited to oxygen reduction reaction. Subsequently, potential stability/durability improvement strategies by tuning catalyst composition, structure, morphology and surface are delineated, including construction of robust substrate and metal-support interaction, optimization of active site stability, fabrication of porosity and surface modification. Finally, the challenges and prospects for robust SACs are discussed. This review facilitates the fundamental understanding of catalyst degradation mechanism and provides efficient design principles aimed at overcoming deactivation difficulties for SACs and beyond.

Nanoscale Confinement-Induced Atom-Milling Pd Nano-Sheets Into Ultra-Fine Pd3Co Alloys

Atomic regulation of nanocatalysts is of both scientific and technological importance in efficient hydrogen energy conversion technology. Here a feasible nanoscale confinement-induced atom-milling (NCAM) method is reported to synthesize and atomically mesh 1 nm thick Pd metallic films into ultra-fine Pd3Co nanoalloys. The nano-sized inner space of layered crystalline provides a nano-scaled limitation (1.3 nm) for atoms' collision, which forces the assembly of hydrogen or Co atoms into a Pd lattice to expand or contract crystal as atom-milling. The resulting ultra-fine Pd3Co nanoalloys exhibit nearly three times higher activity than commercial Pt/C for oxygen reduction reaction, and 2.3 times higher activity than Pd/C for formic acid electrooxidation reaction, for fuel cells, and wider electrocatalysis applications.

Defying the oxidative-addition prerequisite in cross-coupling through artful single-atom catalysts

Heterogeneous single-atom catalysts (SACs) have gained significant attention for their maximized atom utilization and well-defined active sites, but they often struggle with multi-stage organic cross-coupling reactions due to limited coordination space and reactivity. Here, we report an "anchoring-borrowing" strategy combined facet engineering to develop artful single-atom catalysts (ASACs) through anchoring foreign single atoms onto specific facets of the non-innocent reducible carriers. ASACs exhibit adaptive coordination, effectively bypassing the oxidative-addition prerequisite for bivalent elevation at a single metal site in both homogenous and heterogeneous cross-couplings. For example, Pd1-CeO2(110) ASAC exhibits unparalleled activity in coupling with more accessible aryl chlorides, and challenging heterocycles, outperforming traditional catalysts with a remarkable turnover number of 45,327,037. Mechanistic studies reveal that ASACs leverage dynamic structural changes, with reducible carriers acting as electron reservoirs, significantly lowering reaction barriers. Furthermore, ASACs enable efficient synthesis of biologically significant compounds, drug intermediates, and active pharmaceutical ingredients (APIs) through a scalable high-speed circulated flow synthesis, underscoring great potential for sustainable fine chemical manufacturing.

Corrosion-resistant single-atom catalysts for direct seawater electrolysis

Direct seawater electrolysis (DSE) for hydrogen production is an appealing method for renewable energy storage. However, DSE faces challenges such as slow reaction kinetics, impurities, the competing chlorine evolution reaction at the anode, and membrane fouling, making it more complex than freshwater electrolysis. Therefore, developing catalysts with excellent stability under corrosion and fulfilling activity is vital to the advancement of DSE. Single-atom catalysts (SACs) with excellent tunability, high selectivity and high active sites demonstrate considerable potential for use in the electrolysis of seawater. In this review, we present the anodic and cathodic reaction mechanisms that occur during seawater cracking. Subsequently, to meet the challenges of DSE, rational strategies for modulating SACs are explored, including axial ligand engineering, carrier effects and protective layer coverage. Then, the application of in-situ characterization techniques and theoretical calculations to SACs is discussed with the aim of elucidating the intrinsic factors responsible for their efficient electrocatalysis. Finally, the process of scaling up monoatomic catalysts for the electrolysis of seawater is described, and some prospective insights are provided.

Tuning Transition Metal 3d Spin state on Single-atom Catalysts for Selective Electrochemical CO2 Reduction

Tuning transition metal spin states potentially offers a powerful means to control electrocatalyst activity. However, implementing such a strategy in electrochemical CO2 reduction (CO2R) is challenging since rational design rules have yet to be elucidated. Here we show how the addition of P dopants to a ferromagnetic element (Fe, Co, and Ni) single-atom catalyst (SAC) can shift its spin state. For instance, with Fe SAC, P dopants enable a switch from low spin state (dx2- y2 0, dz2 0, dxz 2, dyz 1, dxy 2) in Fe-N4 to high spin state (dx2-y2 0, dxz 1, dyz 1, dz2 1, dxy 2) in Fe-N3-P. This is studied using a suite of characterization efforts, including X-ray absorption spectroscopy (XAS), electron spin resonance (ESR) spectroscopy, and superconducting quantum interference device (SQUID) measurements. When used for CO2R, the SAC with Fe-N3-P active sites yields > 90% Faradaic efficiency to CO over a wide potential window of ≈530 mV and a maximum CO partial current density of ≈600 mA cm-2. Density functional theory calculations reveal that high spin state Fe3+ exhibits enhanced electron back donation via the dxz/dyz-π* bond, which enhances *COOH adsorption and promotes CO formation. Taken together, the results show how the SAC spin state can be intentionally tuned to boost CO2R performance.

Anode Alchemy on Multiscale: Engineering from Intrinsic Activity to Impedance Optimization for Efficient Water Electrolysis

The past decade has seen significant progress in proton exchange membrane water electrolyzers (PEMWE), but the growing demand for cost-effective electrolytic hydrogen pushes for higher efficiency at lower costs. As a complex system, the performance of PEMWE is governed by a combination of multiscale factors. This review summarizes the latest progress from quantum to macroscopic scales. At the quantum level, electron spin configurations can be optimized to enhance catalytic activity. At the nano and meso scales, advancements in atomic structure optimization, crystal phase engineering, and heterostructure design improve catalytic performance and mass transport. At the macro scale, innovative techniques in gas bubble management and internal resistance reduction drive further efficiency gains under ampere-level operating conditions. These modifications at the quantum level cascade through meso- and macro-scales, affecting charge transfer, reaction kinetics, and gas evolution management. Unlike conventional approaches that focus solely on one scale-either at the catalyst level (e.g., atomic, or crystal modifications) or at the device level (e.g., porous transport layers design)-combining multiscale optimizations unlocks greater performance improvements. Finally, a perspective on future opportunities for multiscale engineering in PEMWE anode design toward commercial viability is offered.

Isolated Metal Centers Activate Small Molecule Electrooxidation: Mechanisms and Applications

Electrochemical oxidation of small molecules shows great promise to substitute oxygen evolution reaction (OER) or hydrogen oxidation reaction (HOR) to enhance reaction kinetics and reduce energy consumption, as well as produce high-valued chemicals or serve as fuels. For these oxidation reactions, high-valence metal sites generated at oxidative potentials are typically considered as active sites to trigger the oxidation process of small molecules. Isolated atom site catalysts (IASCs) have been developed as an ideal system to precisely regulate the oxidation state and coordination environment of single-metal centers, and thus optimize their catalytic property. The isolated metal sites in IASCs inherently possess a positive oxidation state, and can be more readily produce homogeneous high-valence active sites under oxidative potentials than their nanoparticle counterparts. Meanwhile, IASCs merely possess the isolated metal centers but lack ensemble metal sites, which can alter the adsorption configurations of small molecules as compared with nanoparticle counterparts, and thus induce various reaction pathways and mechanisms to change product selectivity. More importantly, the construction of isolated metal centers is discovered to limit metal d-electron back donation to CO 2p* orbital and reduce the overly strong adsorption of CO on ensemble metal sites, which resolve the CO poisoning problems in most small molecules electro-oxidation reactions and thus improve catalytic stability. Based on these advantages of IASCs in the fields of electrochemical oxidation of small molecules, this review summarizes recent developments and advancements in IASCs in small molecules electro-oxidation reactions, focusing on anodic HOR in fuel cells and OER in electrolytic cells as well as their alternative reactions, such as formic acid/methanol/ethanol/glycerol/urea/5-hydroxymethylfurfural (HMF) oxidation reactions as key reactions. The catalytic merits of different oxidation reactions and the decoding of structure-activity relationships are specifically discussed to guide the precise design and structural regulation of IASCs from the perspective of a comprehensive reaction mechanism. Finally, future prospects and challenges are put forward, aiming to motivate more application possibilities for diverse functional IASCs.

System Design Considerations for Magneto-Electrocatalysis of the Oxygen Evolution Reaction

The integration of an external magnetic field into electrocatalysis, termed magneto-electrocatalysis, can target efficiency challenges in the oxygen evolution reaction (OER). Reaction rates can be enhanced through improved mass transport of reactants and products, manipulation of spin states, and lowered resistance. The OER is a kinetic bottleneck in electrocatalytic water splitting for sustainable hydrogen fuel. Previous studies lack comprehensive analyses and consistent reporting of magnetic field effects, resulting in varied interpretations. To establish optimized and reliable systems at larger scales, significant research advancements are required. This perspective explores the complex impact of magnetic fields on OER, emphasizing the interplay between various mechanisms such as spin-polarization of oxygen intermediates, Lorentz force-induced magnetohydrodynamics, and magnetoresistance. Here, how experimental design - such as electrode magnetism, shape, positioning, and reactor setup - can significantly influence these mechanisms is highlighted. Through a comprehensive review of current studies, major knowledge gaps and propose methodologies are identified to improve experimental reproducibility and comparability. This article aims to guide researchers toward the development of more efficient, scalable systems that leverage magnetic fields to enhance water splitting to push forward commercial green hydrogen production.

Optimizing photocatalysis via electron spin control

Solar-driven photocatalytic technology holds significant potential for addressing energy crisis and mitigating global warming, yet is limited by light absorption, charge separation, and surface reaction kinetics. The past several years has witnessed remarkable progress in optimizing photocatalysis via electron spin control. This approach enhances light absorption through energy band tuning, promotes charge separation by spin polarization, and improves surface reaction kinetics via strengthening surface interaction and increasing product selectivity. Nevertheless, the lack of a comprehensive and critical review on this topic is noteworthy. Herein, we provide a summary of the fundamentals of electron spin control and the techniques employed to scrutinize the electron spin state of active sites in photocatalysts. Subsequently, we highlight advanced strategies for manipulating electron spin, including doping design, defect engineering, magnetic field regulation, metal coordination modulation, chiral-induced spin selectivity, and combined strategies. Additionally, we review electron spin control-optimized photocatalytic processes, including photocatalytic water splitting, CO2 reduction, pollutant degradation, and N2 fixation, providing specific examples and detailed discussion on underlying mechanisms. Finally, we outline perspectives on further enhancing photocatalytic activity through electron spin manipulation. This review seeks to offer valuable insights to guide future research on electron spin control for improving photocatalytic applications.

Metal Doping Activation of Anion-Mediated Electron Transfer in Catalytic Reactions

Heteroatom-doping has emerged as a transformative approach to producing high-performance catalysts, yet the current trial-and-error approach to optimize these materials remains ineffective. To enable the rational design of more efficient catalysts, models grounded in a deeper understanding of catalytic mechanisms are essential. Existing models, such as d-band center theory, fall short in explaining the role of dopants, particularly when these dopants do not directly interact with reactants. In this study, we synthesize various heteroatom-doped catalysts to explore the correlation between the electronic effects of the dopants and catalyst activity. Using Co-MoS2 as a model catalyst and the Li-S redox reaction within the cathode of Li-S batteries as a test system, we show the interaction between cobalt sites and adjacent lattice sulfur atoms disrupts the intrinsic structural and electronic symmetry of MoS2. This disruption enhances the transfer of spin-polarized electrons from metal centers to lattice sulfur and promotes the adsorption of reactant intermediates. Furthermore, by analyzing 20 different dopant elements, we establish a linear relationship between the electron density in the lattice sulfur and catalyst activity toward the reduction of sulfur species, a relationship that extends to other catalytic systems, such as the hydrogen evolution reaction.

Phenomenological Modeling of Electron-Hole Recombination in Promising Photocatalytic Magnetic Materials

Recent experiments have demonstrated impressive photocatalytic performances in spin-polarized materials. The existence of spin-dependent recombination between spin split bands has been suggested as the cause for at least part of the improved photocatalysis. To test the efficacy of this mechanism, we develop a set of rate equations for carrier charge and spin to shed light on recent experiments with metal-defected or doped oxides, magnetically decorated metal-organic frameworks, and magnetically doped perovskites. Our results show that recombination will be dependent on the band spin polarization and the lengthening of decay times can be optimized by engineering the electronic structure.

Modulation of Electrochemical Reactions through External Stimuli: Applications in Oxygen Evolution Reaction and Beyond

Electrochemical water splitting is a promising method for generating green hydrogen gas, offering a sustainable approach to addressing global energy challenges. However, the sluggish kinetics of the anodic oxygen evolution reaction (OER) poses a great obstacle to its practical application. Recently, increasing attention has been focused on introducing various external stimuli to modify the OER process. Despite significant enhancement in catalytic performance, an in-depth understanding of the origin of superior OER activity contributed by the external stimuli remains elusive, which significantly hinders the further development of highly efficient and durable water electrolyzed devices. Herein, this review systematically summarizes the recent advancements in the understanding of various external stimuli, including photon irradiation, applied magnetic field, and thermal heating, etc., to boost OER activities. In particular, the underlying mechanisms of external stimuli to promote species transfer, modify the electronic structure of electrocatalysts, and accelerate structural reconstruction are highlighted. Additionally, applications of external stimuli in other electrocatalytic reactions are also presented. Finally, several remaining challenges and future opportunities are discussed, providing insights that could further the study of external stimuli in electrocatalytic reactions and support the rational design of highly efficient energy storage and conversion devices.

Atomic Gap-State Engineering of MoS2 for Alkaline Water and Seawater Splitting

Transition-metal dichalcogenides (TMDs), such as molybdenum disulfide (MoS2), have emerged as a generation of nonprecious catalysts for the hydrogen evolution reaction (HER), largely due to their theoretical hydrogen adsorption energy close to that of platinum. However, efforts to activate the basal planes of TMDs have primarily centered around strategies such as introducing numerous atomic vacancies, creating vacancy-heteroatom complexes, or applying significant strain, especially for acidic media. These approaches, while potentially effective, present substantial challenges in practical large-scale deployment. Here, we report a gap-state engineering strategy for the controlled activation of S atom in MoS2 basal planes through metal single-atom doping, effectively tackling both efficiency and stability challenges in alkaline water and seawater splitting. A versatile synthetic methodology allows for the fabrication of a series of single-metal atom-doped MoS2 materials (M1/MoS2), featuring widely tunable densities with each dopant replacing a Mo site. Among these (Mn1, Fe1, Co1, and Ni1), Co1/MoS2 demonstrates outstanding HER performance in both alkaline and seawater alkaline media, with overpotentials at a mere 159 and 164 mV at 100 mA cm-2, and Tafel slopes at 41 and 45 mV dec-1, respectively, which surpasses all reported TMD-based nonprecious materials and benchmark Pt/C catalysts in HER efficiency and stability during seawater splitting, which can be attributed to an optimal gap-state modulation associated with sulfur atoms. Experimental data correlating doping density and dopant identity with HER performance, in conjunction with theoretical calculations, also reveal a descriptor linked to near-Fermi gap state modulation, corroborated by the observed increase in unoccupied S 3p states.

Defect Engineering of Metal-Based Atomically Thin Materials for Catalyzing Small-Molecule Conversion Reactions

Recently, metal-based atomically thin materials (M-ATMs) have experienced rapid development due to their large specific surface areas, abundant electrochemically accessible sites, attractive surface chemistry, and strong in-plane chemical bonds. These characteristics make them highly desirable for energy-related conversion reactions. However, the insufficient active sites and slow reaction kinetics leading to unsatisfactory electrocatalytic performance limited their commercial application. To address these issues, defect engineering of M-ATMs has emerged to increase the active sites, modify the electronic structure, and enhance the catalytic reactivity and stability. This review provides a comprehensive summary of defect engineering strategies for M-ATM nanostructures, including vacancy creation, heteroatom doping, amorphous phase/grain boundary generation, and heterointerface construction. Introducing recent advancements in the application of M-ATMs in electrochemical small molecule conversion reactions (e.g., hydrogen, oxygen, carbon dioxide, nitrogen, and sulfur), which can contribute to a circular economy by recycling molecules like H2, O2, CO2, N2, and S. Furthermore, a crucial link between the reconstruction of atomic-level structure and catalytic activity via analyzing the dynamic evolution of M-ATMs during the reaction process is established. The review also outlines the challenges and prospects associated with M-ATM-based catalysts to inspire further research efforts in developing high-performance M-ATMs.

In Situ Manipulation of Surface Spin Configurations for Enhanced Performance in Oxygen Evolution Reactions

In situ studies of the relationship between surface spin configurations and spin-related electrocatalytic reactions are crucial for understanding how magnetic catalysts enhance oxygen evolution reaction (OER) performance under magnetic fields. In this work, 2D Fe7Se8 nanosheets with rich surface spin configurations are synthesized via chemical vapor deposition. In situ magnetic force microscopy and Raman spectroscopy reveal that a 200 mT magnetic field eliminates spin-disordered domain walls, forming a spin-ordered single-domain structure, which lowers the OER energy barrier, as confirmed by theoretical calculations. Electrochemical tests show that under a 200 mT magnetic field, the OER overpotential of multidomain Fe7Se8 nanosheets at 10 mA cm-2 decreases from 346 mV to 259 mV, while the magnetic field has minimal effect on single-domain nanosheets. These findings highlight the critical role of spin configurations in enhancing electrocatalytic performance, offering new insights into the design of magnetic catalysts for industrial applications.

Ferromagnetic Fe-TiO2 spin catalysts for enhanced ammonia electrosynthesis

Magnetic field effects (MFE) of ferromagnetic spin electrocatalysts have attracted significant attention due to their potential to enhance catalytic activity under an external magnetic field. However, no ferromagnetic spin catalysts have demonstrated MFE in the electrocatalytic reduction of nitrate for ammonia (NO3RR), a pioneering approach towards NH3 production involving the conversion from diamagnetic NO3- to paramagnetic NO. Here, we report the ferromagnetic Fe-TiO2 to investigate MFE on NO3RR. Fe-TiO2 possesses a high density of atomically dispersed Fe sites and exhibits an intermediate-spin state, resulting in magnetic ordering through ferromagnetism. Assisted by a magnetic field, Fe-TiO2 achieves a Faradaic efficiency (FE) of up to 97% and an NH3 yield of 24.69 mg mgcat-1 at -0.5 V versus reversible hydrogen electrode. Compared to conditions without an external magnetic field, the FE and NH3 yield for Fe-TiO2 under an external magnetic field is increased by ~21.8% and ~ 3.1 times, respectively. In-situ characterization and theoretical calculations show that spin polarization enhances the critical step of NO hydrogenation to NOH by optimizing electron transfer pathways between Fe and NO, significantly boosting NO3RR activity.

A perspective on field-effect in energy and environmental catalysis

The development of catalytic technologies for sustainable energy conversion is a critical step toward addressing fossil fuel depletion and associated environmental challenges. High-efficiency catalysts are fundamental to advancing these technologies. Recently, field-effect facilitated catalytic processes have emerged as a promising approach in energy and environmental applications, including water splitting, CO2 reduction, nitrogen reduction, organic electrosynthesis, and biomass recycling. Field-effect catalysis offers multiple advantages, such as enhancing localized reactant concentration, facilitating mass transfer, improving reactant adsorption, modifying electronic excitation and work functions, and enabling efficient charge transfer and separation. This review begins by defining and classifying field effects in catalysis, followed by an in-depth discussion on their roles and potential to guide further exploration of field-effect catalysis. To elucidate the theory-structure-activity relationship, we explore corresponding reaction mechanisms, modification strategies, and catalytic properties, highlighting their relevance to sustainable energy and environmental catalysis applications. Lastly, we offer perspectives on potential challenges that field-effect catalysis may face, aiming to provide a comprehensive understanding and future direction for this emerging area.

Stabilization of High-Valent Molecular Cobalt Sites through Oxidized Phosphorus in Reduced Graphene Oxide for Enhanced Oxygen Evolution Catalysis

Heterogeneous molecular cobalt (Co) sites represent one type of classical catalytic sites for electrochemical oxygen evolution reaction (OER) in alkaline solutions. There are dynamic equilibriums between Co2+, Co3+ and Co4+ states coupling with OH-/H+ interaction before and during the OER event. Since the emergence of Co2+ sites is detrimental to the OER cycle, the stabilization of high-valent Co sites to shift away from the equilibrium becomes critical and is proposed as a new strategy to enhance OER. Herein, phosphorus (P) atoms were doped into reduced graphene oxide to link molecular Co2+ acetylacetonate toward synthesizing a novel heterogeneous molecular catalyst. By increasing the oxidation states of P heteroatoms, the linked Co sites were spontaneously oxidized from 2+ to 3+ states in a KOH solution through OH- ions coupling at an open circuit condition. With excluding the Co2+ sites, the as-derived Co sites with 3+ initial states exhibited intrinsically high OER activity, validating the effectiveness of the strategy of stabilizing high valence Co sites.

Catalysis under electric-/magnetic-/electromagnetic-field coupling

The ultimate goal of catalysis is to control the cleavage and formation of chemical bonds at the molecular or even atomic level, enabling the customization of catalytic products. The essence of chemical bonding is the electromagnetic interaction between atoms, which makes it possible to directly manipulate the dynamic behavior of molecules and electrons in catalytic processes using external electric, magnetic and electromagnetic fields. In this tutorial review, we first introduce the feasibility and importance of field effects in regulating catalytic reaction processes and then outline the basic principles of electric-/magnetic-/electromagnetic-field interaction with matter, respectively. In each section, we further summarize the relevant important advances from two complementary perspectives: the macroscopic molecular motion (including translation, vibration and rotation) and the microscopic intramolecular electron state alteration (including spin polarization, transfer or excitation, and density of states redistribution). Finally, we discuss the challenges and opportunities for further development of catalysis under electric-/magnetic-/electromagnetic-field coupling.

Structurally Asymmetric Ni-O-Mn Node in Metal-Organic Layers on Carbon Nitride Support for CO2 Photoreduction

The Jahn-Teller (J-T) effect-induced lattice distortion presents an advantageous approach to tailor the electronic structure and CO2 adsorption properties of catalytic centers, consequently conferring desirable photocatalytic CO2 reduction activity and selectivity. Nevertheless, achieving precise J-T distortion control over catalytic sites to enhance CO2 adsorption/activation and target-product desorption remains a formidable challenge. In this work, we successfully induced J-T lattice distortion in neighboring Ni sites by exchanging high-spin Mn2+ into Ni-O-Ni nodes. EXAFS results and DFT simulations revealed that the highly asymmetric Ni-O-Mn nodes induced structural contraction (shortened Ni-O bonds) in the adjacent Ni-O lattice. The magnetic hysteresis loop (M-H) confirmed that the introduction of Mn2+ increased the number of spin electrons, thereby increasing the magnetization intensity. The spin mismatch between photogenerated electrons and holes suppressed charge recombination. Significantly, the d orbitals of the Ni sites in the Ni-O-Mn nodes exhibited strong orbital hybridization with the p orbitals of CO2, as evidenced by the enhanced d-p orbital overlap, facilitating rapid CO2 adsorption and activation. Consequently, the sample featuring lattice-mismatched Ni-O-Mn nodes exhibited an 8.79-fold enhancement in CO production rate compared to the Ni-O-Ni nodes, in the absence of cocatalysts and sacrificial reagents.

Creating Spin Channels in SrCoO3 through Trigonal-to-Cubic Structural Transformation for Enhanced Oxygen Evolution/Reduction Reactions

Oxygen evolution and reduction reactions (OER and ORR) play crucial roles in energy conversion processes such as water splitting and air batteries, where spin dynamics inherently influence their efficiency. However, the specific contribution of spin has yet to be fully understood. In this study, we intentionally introduce a spin channel through the transformation of trigonal antiferromagnetic SrCoO2.5 into cubic ferromagnetic SrCoO3, aiming to deepen our understanding of spin dynamics in catalytic reactions. Based on the results from spherical-aberration-corrected microscopy, synchrotron absorption spectra, magnetic characterizations, and density functional theory calculations, it is revealed that surface electron transfer is predominantly governed by local geometric structures, while the presence of the spin channel significantly enhances the bulk transport of spin-polarized electrons, particularly under high current densities where surface electron transfer is no longer the limiting factor. The overpotential for OER is reduced by at least 70 mV at 150 mA cm-2 due to the enhanced conductivity from spin-polarized electrons facilitated by spin channels, with an expectation of even more significant reductions at higher current densities. This work provides a clearer picture of the role of spin in oxygen-involved electrocatalysis, providing critical insights for the design of more efficient catalytic systems in practical applications.

Modulation of the Second-Beyond Coordination Structure in Single-Atom Electrocatalysts for Confirmed Promotion of Ammonia Synthesis

Although microenvironments surrounding single-atom catalysts (SACs) have been widely demonstrated to have a remarkable effect on their catalytic performances, it remains unclear whether the local structure beyond the secondary coordination shells works as well or not. Herein, we employed a series of metal-organic frameworks (MOFs) with well-defined and tunable second-beyond coordination spheres as model SAC electrocatalysts to discuss the influence of long-distance structure on the ammonia synthesis from nitrate, which were synthesized and denoted as Cu12-NDI-X (X = NMe2, H, F). It is first experimentally confirmed that the remote substitution of function groups beyond the secondary coordination sphere can remarkably affect the activity of ammonia synthesis. Meanwhile, the -H endowed Cu12-NND-H exhibits a superior ammonia yield (35.1 mg·h-1·mgcat-1) and FE (98.7%) to those modified with -NMe2 and -F, which also shows good stability at 100 mA·cm-2. The remarkable promotion of the modulated second-beyond coordination structure is unraveled to result from the adjustable d-band center of the Cu active site leading to promoted adsorption of the NO3- and protonation of key intermediates. Encouraged by its extraordinary ammonia yield, we employed the Cu12-NND-H electrode as a cathode to assemble one rechargeable Zn-nitrate battery that exhibits an impressive power density of 34.0 mW·cm-2, demonstrating its promising application in energy conversion and storage.

Customizing Bonding Affinity with Multi-Intermediates via Interfacial Electron Capture to Boost Hydrogen Evolution in Alkaline Water Electrolysis

Developing efficient and earth-abundant alkaline HER electrocatalysts is pivotal for sustainable energy, but co-regulating its intricate multi-step process, encompassing water dissociation, OH- desorption, and hydrogen generation, is still a great challenge. Herein, we tackle these obstacles by fabricating a vertically integrated electrode featuring a nanosheet array with prominent dual-nitride metallic heterostructures characterized by impeccable lattice matching and excellent conductivity, functioning as a multi-purpose catalyst to fine-tune the bonding affinity with alkaline HER intermediates. Detailed structural characterization and theoretical calculation elucidate that charge redistribution at the heterointerface reduces the O p-W d and H s-W d interactions vs. single nitride, thereby enhancing OH- transfer and H2 release. As anticipated, the resulting WN-NiN/CFP catalyst demonstrates a gratifying low overpotential of 36.8 mV at 10 mA/cm2 for alkaline HER, while concurrently maintaining operational stability for 1300 h at 100 mA/cm2 for overall water splitting. This work presents an effective approach to meticulously optimize multiple site-intermediate interactions in alkaline HER, laying the foundation for efficient energy conversion.

Ultrathin transition metal oxychalcogenide catalysts for oxygen evolution in acidic media

Two-dimensional transition metal dichalcogenides (TMDs) exfoliated from bulk layered materials possess interesting properties. Most transition metal oxides are not layered and therefore cannot be exfoliated. Here we report the synthesis of a family of ultrathin materials-transition metal oxychalcogenides (TMOCs)-and demonstrate their unique properties. Two-dimensional TMOCs (MX x O y , M = group IV or V transition metal, X = chalcogen, O = oxygen; x, y = 0-2) from bulk transition metal dichalcogenides (MX2) have been fabricated using tetrabutylammonium intercalation. The stoichiometry of TMOCs can be adjusted, which enables control of their optical bandgaps and tunability of electrical conductivity by more than eight orders of magnitude. By tuning the chalcogen-to-oxygen ratio along with local atomic structure in TMOCs, it is possible to impart unexpected properties. For example, in contrast to conventional TMDs, the hybrid structure of TMOCs renders them surprisingly stable and electrochemically active in strong acids, allowing them to be used as proof-of-concept catalysts for the oxygen evolution reaction at pH ≈ 0. The HfS0.52O1.09 catalyst shows high mass activity (103,000 A g-1 at an overpotential of 0.5 V) and exhibits durability in proton exchange membrane water electrolysers.

Engineering Magnetic Heterostructures with Synergistic Regulation of Charge-Transfer and Spin-Ordering for Enhanced Water Oxidation

The design of heterojunctions offers a crucial solution for energy conversion and storage challenges, but current research predominantly focuses on charge transfer benefits, often neglecting spin attribute regulation despite the increasing recognition of spin-sensitivity in many chemical reactions. In this study, a novel magnetic heterostructure, CoFe2O4@CoFeMo3O8, is designed to simultaneously modulate charge and spin characteristics, and systematically elucidated their synergistic impact on the oxygen evolution reaction (OER). Experimental results and density functional theory calculations confirmed that the magnetic heterostructure exhibits both charge transfer and spin polarization. It is found that the charge-transfer behavior enhances conductivity and adsorption ability through band structure regulation. Meanwhile, magnetically polarized electrons promote triplet O2 generation and accelerate electron transport via spin-selective pathways. Moreover, the heterostructure's effective response to external alternating magnetic fields further amplifies the spin-dependent effect and introduces a magnetothermal effect, locally heating the active sites through spin flip, thereby boosting catalytic activity. Consequently, the OER activity of the magnetic heterostructure is improved by 83.8 times at 1.5 V compared to its individual components. This magnetic heterojunction strategy presents a promising avenue for advanced catalysis through synergistic regulating of charge-transfer and spin-ordering.

Synergetic Modulation of Electronic Properties of Cobalt Oxide via "Tb" Single Atom for Uphill Urea and Water Electrolysis

Exploring single-atom (SA) catalysts in hybrid urea-assisted water electrolysis offers a viable alternative to both Hydrogen (H2) generation and polluted water treatment. However, the unfavorable electronic stabilization, low SA content, intrinsically slow kinetics, and imbalanced adsorption-desorption steps are the bottleneck for its scale-up implementation. Herein, a rare-earth Terbium single atom (TbSA) is topologically stabilized on defect-rich Co3O4 (TbSA@d-Co3O4) by Tb─O co-ordination for urea oxidation reaction (UOR) and H2 evolution reaction (HER). Benefitting from the strong TbSA interaction with the d-Co3O4, the TbSA@d-Co3O4 achieves a 10 mA cm-2 current density at 1.27 V and -35 mV for UOR and HER, respectively. Remarkably, when TbSA@d-Co3O4 is applied as a bi-functional catalyst in a two-electrode system, it merely requires 1.22 V to acquire 10 mA cm-2 with excellent operational stability for 100 h. The hybrid electrolyzer can be successfully empowered by the triboelectric nanogenerator, AA battery, and solar panel with a nominal potential of 1.5 V. The mechanistic investigation predicts "TbSA" insertion in d-Co3O4 lowered the potential determining step, attributed to balanced reaction energetics for adsorption-desorption of intermediates and favorable charge transfer characteristics for UOR. This work offers a new paradigm to explore the catalytic properties of rare-earth "f-block" elements to create advanced electrocatalysts via structural modulation.

Interface-Triggered Spin-Magnetic Effect in Rare Earth Intraparticle Heterostructured Nanoalloys for Boosting Hydrogen Evolution

Rare earth (RE) elements are attractive for spin-magnetic modulation due to their unique 4 f electron configuration and strong orbital couplings. Alloying RE with conventional 3d transition-metal (TM) is promising for the fabrication of advanced spin catalysts yet remains much difficulties in preparation, which leads to the mysteries of spin-magnetic effect between RE and 3d TM on catalysis. Here we define a solid-phase synthetic protocol for creating RE-3d TM-noble metal integrated intraparticle heterostructured nanoalloys (IHAs) with distinct Gd and Co interface within the entire Rh framework, denoted as RhCo-RhGd IHAs. They exhibit interface-triggered antiferromagnetic interaction, which can induce electron redistribution and regulate spin polarization. Theoretical calculations further reveal that active sites around the heterointerface with weakened spin polarization optimize the adsorption and dissociation of H2O, thus promoting alkaline hydrogen evolution catalysis. The RhCo-RhGd IHAs show a small overpotential of 11.3 mV at 10 mA cm-2, as well as remarkable long-term stability, far superior to previously reported Rh-based catalysts.

Vibrational and Magnetic States of Point Defects in Bilayer MoSe2

Defects in two-dimensional materials profoundly impact the physicochemical properties of the systems, whose characterization is highly desirable at the atomic scale. Here, using spectroscopic imaging scanning tunneling microscopy, we elucidate the vibrational and magnetic states of MoSe antisite and VMo vacancy with different charge states embedded in ultrathin MoSe2 bilayers supported on graphene substrate. Stringent vibronic states with multimode coupling are resolved on the defects. The spectral intensities are tunable with the electron tunneling rates and well-reproduced by theoretical modeling. Moreover, first-principles calculations suggest that the defects host a local magnetic moment of 2 μB in their neutral state, which is directly confirmed by our spin-flip inelastic electron tunneling spectroscopy. Our study deepens the understanding of defect properties and paves the way of defect-engineering material functionalities and spin-catalytic applications.

Iron Doping of 2D Nickel-Based Metal-Organic Frameworks Enhances the Lattice Heterogeneous Interface Coupling Effect for Improved Electrocatalytic Oxygen Evolution

The coupling of lattice and heterostructure interfaces represents an effective strategy for disrupting the so-called scalar relationship and accelerating reactions involving multiple intermediates. In view of this, a lattice-heterostructure interfacial catalyst consisting of a crystalline Fe/Ni bimetallic MOF and amorphous Fe-MOF was designed in this paper for high-performance alkaline oxygen evolution reaction electrocatalysis. The strongly coupled lattice-heterostructure interface induces a unique synergistic effect that promotes electron transfer of the catalyst. The resulting catalyst exhibits exceptionally high catalytic activity for the oxygen evolution reaction in alkaline media, the Ni9Fe1-BDC-1@Fe-MOF coated on a glassy carbon electrode has an overpotential of 257 mV at a current density of 10 mA cm-2. Furthermore, this catalyst demonstrates a high electrochemical stability. These research results highlight the superiority of lattice-heterostructure interfaces in the development of advanced catalysts.

Spin-Polarized PdCu-Fe3O4 In-Plane Heterostructures with Tandem Catalytic Mechanism for Oxygen Reduction Catalysis

Alloying has significantly upgraded the oxygen reduction reaction (ORR) of Pd-based catalysts through regulating the thermodynamics of oxygenated intermediates. However, the unsatisfactory activation ability of Pd-based alloys toward O2 molecules limits further improvement of ORR kinetics. Herein, the precise synthesis of nanosheet assemblies of spin-polarized PdCu-Fe3O4 in-plane heterostructures for drastically activating O2 molecules and boosting ORR kinetics is reported. It is demonstrated that the deliberate-engineered in-plane heterostructures not only tailor the d-band center of Pd sites with weakened adsorption of oxygenated intermediates but also endow electrophilic Fe sites with strong ability to activate O2 molecules, which make PdCu-Fe3O4 in-plane heterostructures exhibit the highest ORR specific activity among the state-of-art Pd-based catalysts so far. In situ electrochemical spectroscopy and theoretical investigations reveal a tandem catalytic mechanism on PdCu-Fe3O4─Fe sites that initially activate molecular O2 and generate oxygenated intermediates being transferred to Pd sites to finish the subsequent proton-coupled electron transfer steps.

Experimental and Theoretical Insights into Single Atoms, Dual Atoms, and Sub-Nanocluster Catalysts for Electrochemical CO2 Reduction (CO2RR) to High-Value Products

Electrocatalytic carbon dioxide (CO2) conversion into valuable chemicals paves the way for the realization of carbon recycling. Downsizing catalysts to single-atom catalysts (SACs), dual-atom catalysts (DACs), and sub-nanocluster catalysts (SNCCs) has generated highly active and selective CO2 transformation into highly reduced products. This is due to the introduction of numerous active sites, highly unsaturated coordination environments, efficient atom utilization, and confinement effect compared to their nanoparticle counterparts. Herein, recent Cu-based SACs are first reviewed and the newly emerged DACs and SNCCs expanding the catalysis of SACs to electrocatalytic CO2 reduction (CO2RR) to high-value products are discussed. Tandem Cu-based SAC-nanocatalysts (NCs) (SAC-NCs) are also discussed for the CO2RR to high-value products. Then, the non-Cu-based SACs, DACs, SAC-NCs, and SNCCs and theoretical calculations of various transition-metal catalysts for CO2RR to high-value products are summarized. Compared to previous achievements of less-reduced products, this review focuses on the double objective of achieving full CO2 reduction and increasing the selectivity and formation rate toward C-C coupled products with additional emphasis on the stability of the catalysts. Finally, through combined theoretical and experimental research, future outlooks are offered to further develop the CO2RR into high-value products over isolated atoms and sub-nanometal clusters.

Dual-synergistic effect of medium-entropy metal sulfoselenide nanoparticles toward efficient overall seawater splitting

Developing efficient and durable electrodes for overall water splitting (OWS) in seawater electrolytes is a major challenge. Herein, we synthesized highly active and stable Fe1.2(CoNi)1.8S3Se3 medium-entropy metal sulfoselenide (MESSe) nanoparticles for the electrodes. The Fe1.2(CoNi)1.8S3Se3 MESSe electrode exhibited excellent electrocatalytic performance in alkaline simulated seawater, with a η100 value of 156 mV for the hydrogen evolution reaction and 262 mV for the oxygen evolution reaction. Compared to Fe1.2(CoNi)1.8S6 sulfide and Fe1.2(CoNi)1.8Se6 selenide, the electronic structure of Fe1.2(CoNi)1.8S3Se3 MESSe positively modulates the adsorption/desorption process of *H/*OH intermediate and significantly reduces the free energy of the rate-determining step, thereby accelerating the reaction kinetics of both hydrogen/oxygen evolution reactions. The performance of OWS is significantly enhanced by utilizing the prepared electrode, enabling it to achieve 100 mA cm-2 with only 1.77 V in alkaline simulated seawater. Furthermore, the durability of the electrode is maintained at this high current density in alkaline simulated seawater, alkaline seawater as well as seawater electrolyte. This work will lay the foundation for the development of innovative medium-entropy metal sulfoselenides, promoting their application in a wide range of electrochemical energy systems operating under extreme conditions.

Understanding the active site in chameleon-like bifunctional catalyst for practical rechargeable zinc-air batteries

The practical application of rechargeable zinc-air batteries faces challenges stemming from inadequate bifunctional catalysts, contradictory gas-liquid-solid three-phase interfaces, and an ambiguous fundamental understanding. Herein, we propose a chameleon-like bifunctional catalyst comprising ruthenium single-atoms grafted onto nickel-iron layer double hydroxide (RuSA-NiFe LDH). The adaptive oxidation of RuSA-NiFe LDH to oxyhydroxide species (RuSA-NiFeOOH) during charging exposes active sites for the oxygen evolution reaction, while reversible reduction to NiFe LDH during discharge exposes active sites for the oxygen reduction reaction. Additionally, a hierarchical air cathode featuring hydrophilic and hydrophobic layers facilitates the reversible conversion between RuSA-NiFe LDH and RuSA-NiFeOOH, expedites oxygen bubble desorption, and suppresses carbon corrosion. Consequently, our zinc-air batteries demonstrate a high charge/discharge capacity of 100 mAh cm-2 per cycle, a voltage gap of 0.67 V, and an extended cycle life of 2400 h at 10 mA cm-2. We comprehensively elucidate the catalytic reaction thermodynamics and kinetics for the air cathode through electrode potential decoupling monitoring, oxygen bubble desorption tracking, and carbon content quantification.

Magnetically Enhanced Oxygen Evolution Reaction in Mild Alkaline Electrolytes by Building Catalysts on Magnetic Frame

Under large current densities, the excessive hydroxide ion (OH) consumption hampers alkaline water splitting involving the oxygen evolution reaction (OER). High OH concentration (≈30 wt.%) is often used to enhance the catalytic activity of OER, but it also leads to higher corrosion in practical systems. To achieve higher catalytic activity in low OH concentration, catalysts on magnetic frame (CMF) are built to utilize the local magnetic convection induced from the host frame's magnetic field distributions. This way, a higher reaction rate can be achieved in relatively lower OH concentrations. A CMF model system with catalytically active CoFeOx nanograins grown on the magnetic Ni foam is demonstrated. The OER current of CoFeOx@NF receives ≈90% enhancement under 400 mT (900 mA cm-2 at 1.65 V) compared to that in zero field, and exhibits remarkable durability over 120 h. As a demonstration, the water-splitting performance sees a maximum 45% magnetic enhancement under 400 mT in 1 m KOH (700 mA cm-2 at 2.4 V), equivalent to the concentration enhancement of the same electrode in a more corrosive 2 m KOH electrolyte. Therefore, the catalyst-on-magnetic-frame strategy can make efficient use of the catalysts and achieve higher catalytic activity in low OH concentration by harvesting local magnetic convection.

Spin Manipulation of Heterogeneous Molecular Electrocatalysts by an Integrated Magnetic Field for Efficient Oxygen Redox Reactions

Understanding the spin-dependent activity of nitrogen-coordinated single metal atom (M-N-C) electrocatalysts for oxygen reduction and evolution reactions (ORR and OER) remains challenging due to the lack of structure-defined catalysts and effective spin manipulation tools. Herein, both challenges using a magnetic field integrated heterogeneous molecular electrocatalyst prepared by anchoring cobalt phthalocyanine (CoPc) deposited carbon black on polymer-protected magnet nanoparticles, are addressed. The built-in magnetic field can shift the Co center from low- to high-spin (HS) state without atomic structure modification, affording one-order higher turnover frequency, a 50% increased H2O2 selectivity for ORR, and a ≈4000% magnetocurrent enhancement for OER. This catalyst can significantly minimize magnet usage, enabling safe and continuous production of a pure H2O2 solution for 100 h from a 100 cm2 electrolyzer. The new strategy demonstrated here also applies to other metal phthalocyanine-based catalysts, offering a universal platform for studying spin-related electrochemical processes.

Optimizing the Intermediates Adsorption by Manipulating the Second Coordination Shell of Ir Single Atoms for Efficient Water Oxidation

The precise regulation of single-atom catalysts (SACs) with the desired local chemical environment is vital to elucidate the relationship between the SACs structure and the catalytic performance. The debate on the effect of the local coordination environment is quite complicated even for the SACs with the same composition and chemical nature, calling for increased attention on the regulation of the second coordination shell. For oxide-supported SACs, it remains a significant challenge to precisely manipulate the second coordination shell of single atoms supported on oxides due to the structural robustness of oxides. Here, Ir single atoms were anchored on NiO supports via different bonding strategies, resulting in the diverse Ir-O-Ni coordination numbers for Ir sites. Specifically, Ir1/NiO, Ir1-NiO, and Ir1@NiO SACs with increasing Ir-O-Ni coordination numbers of 3, 4, and 5 were synthesized, respectively. We found that the activity of the three samples towards oxygen evolution reaction (OER) exhibited a volcano-shaped relationship with the Ir-O-Ni coordination number, with Ir1-NiO showing the lowest overpotential of 225 mV at 10 mA cm-2. Mechanism investigations indicate that the moderate coordination number of Ir-O-Ni in Ir1-NiO creates the higher occupied Ir dz2 orbital, weakening the adsorption strength for *OOH intermediates and thereby enhancing the OER activity.