Sulfur-Bridged Asymmetric CuNi Bimetallic Atom Sites for CO2 Reduction with High Efficiency

Spin Engineering of Dual-Atom Site Catalysts for Efficient Electrochemical Energy Conversion

Dual-atom site catalysts (DASCs) provide more advantages than single-atom systems in improving energy conversions, owing to their unique features. For example, the coupling effect may align the spin of two adjacent dual-atom active centers in parallel or antiparallel via electron exchange interactions, thereby altering reaction mechanisms and overall efficiency. While numerous reviews have explored spin-dependent electrocatalysis, there remains a lack of a comprehensive, spin-focused framework for understanding the catalytic behavior of DASCs. This review emphasizes the role of spin in dual-atom site centers for electrocatalysis research. First, spin fundamentals in electrocatalysts, including spin-selective orbital occupation, spin ordering, and spin coupling, are comprehensively summarized to provide a solid foundation for subsequent discussions. Then, spin engineering strategies of DASCs are reviewed, including manipulating the spin configuration of the central atoms, modulating coordination environments, and tuning metal-support interactions. Next, recent developments in spin engineering of DASCs are reviewed, with a focus on structure-performance relationships. Furthermore, high-throughput screening techniques integrated with machine learning are discussed for developing highly efficient DASCs based on spin engineering. The challenges and opportunities of DASCs and spin engineering are thoroughly discussed to promote the advancement of new energy applications.

The dual selective adsorption mechanism on low-concentration Cu(II): Structural confinement and bridging effect

In this study, sulfur was introduced into the graphene oxide-based aerogel system based on the theory of bridging effect, and an oxygen-sulfur synergistic system was established to realize the dual-mechanism selective adsorption to low-concentration Cu(II) with slit structure and targeted binding sites. Based on the difference of chemical properties between organic acids and surfactants, the surface of graphene oxide (GO) was functionalized to realize the regulation of the order of its lamellar structure and the construction of carbon defects. On this basis, sulfur source modified GO-based aerogel was created to accomplish selective adsorption to low-concentration Cu(II) by combining the self-accumulation of montmorillonite and GO with the cross-linking mechanism of Ca(II) and sodium alginate. Based on the density functional theory, the formation process of radicals on the material's surface both prior to and following the adsorption to Cu(II) was simulated, and the effective improvement on the catalytic ability of the material after loading Cu(II) was verified. This means that using Cu(II) saturated adsorbent as a photocatalyst to degrade organic pollutants, is a promising reuse strategy for hazardous waste. The above research provides a new research idea for the subsequent removal of low-concentration metal ions and the potential application of hazardous wastes.

Hydrogenation of "Readily Activated Molecule" for Glycine Electrosynthesis

The hydrogenation of glyoxylate oxime is the energy-intensive step in glycine electrosynthesis. To date, there has been a lack of rational guidance for catalyst design specific to this step, and the unique characteristics of the oxime molecule have often been overlooked. In this study, we initiate a theoretical framework to elucidate the fundamental mechanisms of glycine electrosynthesis across typical transition metals. By comprehensively analyzing the competitive reactions, proton-coupled electron transfer processes, and desorption steps, we identify the unique role of the glyoxylate oxime as a "readily activated molecule". This inherent property positions Ag, featuring weak adsorption characteristics, as the "dream" catalyst for glycine electrosynthesis. Notably, a record-low onset potential of -0.09 V versus RHE and an impressive glycine production rate of 1327 µmol h-1 are achieved when using an ultralight Ag foam electrode. This process enables gram-scale glycine production within 20 h and can be widely adapted for synthesizing diverse amino acids. Our findings underscore the vital significance of considering the inherent characteristics of reaction intermediates in catalyst design.

Advances in the Structure-Activity Relationship of Electrocatalytic C-N Coupling: From Nanocatalysis to Single Metal Site Catalysis

C-N coupling is crucial for constructing amides and amines and involves various fields, including medicine, chemical industries, agriculture, and energy. With the rapid development of electrocatalytic C-N coupling and the continuous improvement of catalytic performance, this field has aroused extensive research interest. A comprehensive review is urgently needed to summarize the structure-activity relationship, key challenges, and future development directions. This review provides a concise overview of the recent advancements from nanocatalysis to single metal site catalysis for electrocatalytic C-N coupling reactions. We summarize the C-N coupling mechanisms using different nitrogen sources and further analyze the influences of various active metal centers and different coordination environments on the C-N coupling performance, thereby elucidating the structure-activity relationship. Moreover, we discuss the dynamic structural evolution of active metal sites during the reaction. Finally, we present current challenges and perspectives in this field. This review aims to provide valuable insights into the development of advanced nano/single metal site catalysts for electrocatalytic C-N coupling reactions along with a deeper understanding of catalytic mechanisms.

A Triatomic Cobalt Catalyst for Oxygen Electrocatalysis

The advancement of rechargeable zinc-air batteries significantly depends on bifunctional oxygen electrocatalysts to provide outstanding oxygen reduction/evolution reaction (ORR/OER) performance. However, it is still challenging to design electrocatalysts with excellent bifunctional activity and stability. Here, we adopt an ultrafast printing method to efficiently embed a triatom cobalt complex precursor onto graphene nanosheets to obtain a triatomic catalyst (Co3-NG), exhibiting a durable and excellent bifunctional catalyst in the electrocatalytic ORR (Ehalf-wave = 0.903 V) and OER (Ej = 10 = 1.596 V). The Co3-NG-assembled zinc-air battery can output a maximum power density of 189.0 mW cm-2 at 330 mA cm-2 and can be charged and discharged over 3000 cycles, significantly outperforming the Pt/C + RuO2 benchmark (146.5 mW cm-2, 360 cycles) under testing conditions of 25 °C. In situ XAS analysis and theoretical calculations disclose that Co3ON6 is the catalytic site for bifunctional ORR/OER electrocatalysis. The constructed triangular pyramidal active sites effectively regulate the d-band center and electronic configuration and promote the adsorption/desorption of oxygen intermediates. This work uncovers that the geometry and electronic structure of triatomic active centers play a key role in improving bifunctional ORR/OER performance for electrochemical energy applications.

Oxygen vacancy-engineered bimetallic nanozymes for disrupting electron transport chain and synergistic multi-enzyme activity to reverse oxaliplatin resistance in colorectal cancer

In colorectal cancer treatment, chemotherapeutic agents induce reactive oxygen species (ROS) production, which promotes NAD+ accumulation in tumor cells, reducing treatment sensitivity and worsening patient prognosis. Targeted depletion of NAD+ presents a promising strategy to overcome tumor resistance and improve patient prognosis. Here, we designed a dual-metallic nanozyme (CuMnOx-V@Oxa@SP) with defect engineering, modified by soy phospholipids (SP) and loaded with oxaliplatin (Oxa). This nanozyme uses its oxygen-deficient active sites to rapidly and irreversibly degrade NAD⁺ and NADH into nicotinamide and ADP-ribose derivatives, disrupting the electron transport chain (ETC) and compromising tumor antioxidant defenses. It also inhibits the glutathione S-transferase P1 (GSTP1) pathway, weakening tumor detoxification and enhancing chemotherapy sensitivity. Density functional theory calculations revealed that the synergistic effect among multi-enzyme active centers endows the CuMnOx-V nanozymes with excellent catalytic activity. In the tumor microenvironment (TME), CuMnOx-V nanozymes exhibit peroxidase, oxidase, and NAD+ oxidase-mimicking activities. CuMnOx-V generates multiple ROS and depletes NAD+ while preventing their regeneration thereby triggering a cascade amplification of oxidative stress. This, coupled with targeted chemotherapy drug delivery, restores chemosensitivity in refractory tumors and exposes the vulnerabilities of resistant colorectal cancer cells to ROS.

Sulfur-modified charge-asymmetry FeNi nanoalloy catalysts anchored on N-doped carbon nanosheets for efficient electrochemical CO2 reduction

The electrochemical carbon dioxide reduction reaction (CO2RR) plays a crucial role in mitigating global CO2 emissions and achieving carbon neutrality. In this study, we present a sulfur-doped FeNi alloy on a nitrogen-doped carbon substrate (FeNi Alloy/SNC) as a highly active CO2RR catalyst. This advanced charge-asymmetric nanocluster catalyst features sulfur-doped Fe-Ni bimetallic sites. X-ray absorption spectroscopy (XAS) was used to verify the presence of these S-doped asymmetric bimetallic sites. The charge-asymmetric catalysts exhibited 98.1% CO conversion efficiency, which significantly surpassed that of S-containing Fe cluster/SNC, Ni cluster/SNC, and S-free FeNi/NC, Ni/NC, and Fe/NC catalysts. Furthermore, in situ synchrotron radiation XAS analysis revealed that the S-doped Fe-Ni bimetallic sites enhanced charge transfer between the metal centers, thereby facilitating the accelerated production of CO.

Low-Temperature Pyrolysis: A Universal Route to High-Loading Single-Atom Catalysts for Fuel Cells

High-temperature pyrolysis (HTP, ≥900 °C) is a widely used method for synthesizing single-atom catalysts (SACs). However, the high operational temperatures required for HTP pose significant challenges in achieving high single-atom loading, primarily due to the Ostwald ripening effect. In this work, a low-temperature trans-metalation synthesis approach is developed which involves the exchange of cation between transition metal ions (M = Fe, Co, Cu, Ni, Mn, etc) and Zn2+ ions on a nitrogen-doped carbon (NC) matrix within a molten salt medium. This strategy effectively avoids phase transformations and enables the direct formation of high mass loading (3.7-4.7 wt.%) of atomically dispersed M-N4 sites. Both experimental and theoretical analyses confirm that this cation-exchange occurs at a lower temperature threshold of 450 °C, significantly reducing the energy barriers for SACs synthesis. Furthermore, the synthesized catalyst with atomically dispersed Fe sites demonstrate excellent performance toward oxygen reduction reaction and fuel cell with a peak power density of 1.12 W cm-2 in an H2─O2 fuel cell at 1.0 bar and 80 °C.

Improving Conversion Kinetics of Sodium Polysulfides through Electron Spillover Effect with V/Co Dual-Atomic Site Anchoring on N-Doped MXene

Room-temperature sodium─sulfur (RT/Na─S) batteries, with a theoretical capacity of 1672 mAh g⁻1, face challenges such as the insulating nature of sulfur and slow redox kinetics, particularly during complex liquid-solid (Na2S4→Na2S2) and solid-solid (Na2S2→Na2S) conversions. Herein, vanadium-cobalt (VCo) diatomic sites implanted in vacancy-rich N-doped MXene (VCo DACs/N-MXene) are introduced to address these issues. The N-bridged VCo diatomic pairs are demonstrated and their strong electronic interactions are also validated through experimental and theoretical analyses. The RT/Na─S battery with optimized VCo DACs/N-MXene delivers an average capacity of 1255.3 mAh g⁻1 at 0.1 C and remarkable cycling stability, with only ≈0.001% capacity decay per cycle over 1500 cycles at 1 C. DFT calculations reveal that VCo diatomic sites enhance reaction kinetics by reducing the Gibbs free energy for polysulfide conversions, notably reducing the solid-solid conversion energy barriers from 1.17/0.96 eV for V/Co SACs/N-MXene to 0.53 eV for VCo DACs/N-MXene. XANES and DFT analyses attribute this improvement to a unique electron spillover effect, facilitating efficient electron transport during charge and discharge. This work highlights the potential of optimizing electronic configurations and coordinating environments to activate bidirectional kinetics with improved capacity and longevity of RT/Na─S batteries.

Engineering High-Density Grain Boundaries in Ru0.8Ir0.2Ox Solid-Solution Nanosheets for Efficient and Durable OER Electrocatalysis

The oxygen evolution reaction (OER) in proton exchange membrane water electrolyzers (PEMWE) has long stood as a formidable challenge for green hydrogen sustainable production, hindered by sluggish kinetics, high overpotentials, and poor durability. Here, these barriers are transcended through a novel material design: strategic engineering of high-density grain boundaries within solid-solution Ru0.8Ir0.2Ox ultrathin nanosheets. These carefully tailored grain boundaries and synergistic Ir─Ru interactions, reduce the coordination of Ru atoms and optimize the distribution of charge, thereby enhancing both the catalytic activity and stability of the nanosheets, as verified by merely requiring an overpotential of 189 mV to achieve 10 mA cm-2 in acidic electrolyte. In situ electrochemical techniques, complemented by theoretical calculations, reveal that the OER follows an adsorption evolution mechanism, demonstrating the pivotal role of grain boundary engineering and electronic modulation in accelerating reaction kinetics. Most notably, the Ru0.8Ir0.2Ox exhibits outstanding industrial-scale performance in PEMWE, reaching 4.0 A cm-2 at 2 V and maintaining stability for >1000 h at 500 mA cm-2. This efficiency reduces hydrogen production costs to $0.88 kg-1. This work marks a transformative step forward in designing efficient, durable OER catalysts, offering a promising pathway toward hydrogen production technologies and advancing the global transition to sustainable energy.

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.

Breaking symmetry for better catalysis: insights into single-atom catalyst design

Breaking structural symmetry has emerged as a powerful strategy for fine-tuning the electronic structure of catalytic sites, thereby significantly enhancing the electrocatalytic performance of single-atom catalysts (SACs). The inherent symmetric electron density in conventional SACs, such as M-N4 configurations, often leads to suboptimal adsorption and activation of reaction intermediates, limiting their catalytic efficiency. By disrupting this symmetry of SACs, the electronic distribution around the active center can be modulated, thereby improving both the selectivity and adsorption strength for key intermediates. These changes directly impact the reaction pathways, lowering energy barriers, and enhancing catalytic activity. However, achieving precise modulation through SAC symmetry breaking for better catalysis remains challenging. This review focuses on the atomic-level symmetry-breaking strategies of catalysts, including charge breaking, coordination breaking, and geometric breaking, as well as their electrocatalytic applications in electronic structure tuning and active site modulation. Through modifications to the M-N4 framework, three primary configurations are achieved: unsaturated coordination M-Nx(x=1,2,3), non-metallic doping MX-Nx(x=1,2,3), and bimetallic doping M1M2-N4. Advanced characterization techniques combined with density functional theory (DFT) elucidate the impact of these strategies on oxidation, reduction, and bifunctional catalytic reactions. This review highlights the significance of symmetry-breaking structures in catalysis and underscores the need for further research to achieve precise control at the atomic-level.

Sulfur Bridge Geometry Boosts Selective FeIV═O Generation for Efficient Fenton-Like Reactions

High-valent iron-oxo species (FeIV═O) is a fascinating enzymatic agent with excellent anti-interference abilities in various oxidation processes. However, selective and high-yield production of FeIV═O remains challenging. Herein, Fe diatomic pairs are rationally fabricated with an assisted S bridge to tune their neighbor distances and increase their loading to 11.8 wt.%. This geometry regulated the d-band center of Fe atoms, favoring their bonding with the terminal and hydroxyl O sites of peroxymonosulfate (PMS) via heterolytic cleavage of O─O, improving the PMS utilization (70%), and selective generation of FeIV═O (>90%) at a high yield (63% of PMS) offers competitive performance against state-of-the-art catalysts. These continuous reactions in a fabricated device and technol-economic assessment further verified the catalyst with impressive long-term activity and scale-up potential for sustainable water treatment. Altogether, this heteroatom-bridge strategy of diatomic pairs constitutes a promising platform for selective and efficient synthesis of high-valent metal-oxo species.

Bimetallic effects in carbon dioxide electroreduction

As a clean and sustainable technology, electrocatalytic carbon dioxide reduction reaction (ECO2RR) occupies a central position in the global energy transformation and climate change strategy. Compared with single metallic catalysts, bimetallic catalysts have many advantages, such as the synergistic effect between bimetals, enhanced CO2 adsorption capacity, and lower reaction energy barriers, which make them widely used in the CO2RR for the generation of multi-carbon products. This review systematically summarizes the latest advances in bimetallic effects for the CO2RR. In this paper, we start with a classified introduction on the CO2RR mechanisms, followed by a comprehensive discussion of the structure-activity relationships of various bimetallic catalysts, including regulation of metal centers, regulation of the distance between metal sites, regulation of the coordination environment, interface engineering, and strain engineering. Next, we showcase the advantages of bimetallic catalysts in the CO2RR. Then, the research progress of typical bimetallic catalysts for the ECO2RR is discussed, including diatomic catalysts, bimetallic alloys, bimetallic MOFs and bimetallic COFs. Finally, we summarize the challenges faced today from the five aspects of product selectivity, catalyst stability, product purification, theoretical simulations and in situ characterization techniques and put forward the research direction to promote the industrialization process of CO2RR.

Asymmetric Charge Distribution in Atomically Precise Metal Nanoclusters for Boosted CO2 Reduction Catalysis

Recently, atomically precise metal nanoclusters (NCs) have been widely applied in CO2 reduction reaction (CO2RR), achieving exciting activity and selectivity and revealing structure-performance correlation. However, at present, the efficiency of CO2RR is still unsatisfactory and cannot meet the requirements of practical applications. One of the main reasons is the difficulty in CO2 activation due to the chemical inertness of CO2. Constructing symmetry-breaking active sites is regarded as an effective strategy to promote CO2 activation by modulating electronic and geometric structure of CO2 molecule. In addition, in the subsequent CO2RR process, asymmetric charge distributed sites can break the charge balance in adjacent adsorbed C1 intermediates and suppress electrostatic repulsion between dipoles, benefiting for C-C coupling to generate C2+ products. Although compared to single atoms, metal nanoparticles, and inorganic materials the research on the construction of asymmetric catalytic sites in metal NCs is in a newly-developing stage, the precision, adjustability and diversity of metal NCs structure provide many possibilities to build asymmetric sites. This review summarizes several strategies of construction asymmetric charge distribution in metal NCs for boosting CO2RR, concludes the mechanism investigation paradigm of NCs-based catalysts, and proposes the challenges and opportunities of NCs catalysis.

Sulfur-doping tunes p-d orbital coupling over asymmetric Zn-Sn dual-atom for boosting CO2 electroreduction to formate

The interaction of p-d orbitals at bimetallic sites plays a crucial role in determining the catalytic reactivity, which facilitates the modulation of charges and enhances the efficiency of CO2 electroreduction process. Here, we show a ligand co-etching approach to create asymmetric Zn-Sn dual-atom sites (DASs) within metal-organic framework (MOF)-derived yolk-shell carbon frameworks (named Zn1Sn1/SNC). The DASs comprise one Sn center (p-block) partially doped with sulfur and one Zn center (d-block) with N coordination, facilitating the coupling of p-d orbitals between the Zn-Sn dimer. The N-Zn-Sn-S/N arrangement displays an asymmetric distribution of charges and atoms, leading to a stable adsorption configuration of HCOO* intermediates. In H-type cell, Zn1Sn1/SNC exhibits an impressive formate Faraday efficiency of 94.6% at -0.84 V. In flow cell, the asymmetric electronic architecture of Zn1Sn1/SNC facilitates high accessibility, leading to a high current density of -315.2 mA cm-2 at -0.90 V. Theoretical calculations show the asymmetric sites in Zn1Sn1/SNC with ideal adsorption affinity lower the CO2 reduction barrier, thus improve the overall efficiency of CO2 reduction.

Unveiling the Mystery of Precision Catalysis: Dual-Atom Catalysts Stealing the Spotlight

In the era of atomic manufacturing, the precise manipulation of atomic structures to engineer highly active catalytic sites has become a central focus in catalysis research. Dual-atom catalysts (DACs) have garnered significant attention for their superior activity, selectivity, and stability compared to single-atom catalysts (SACs). However, a comprehensive review that integrates geometric and electronic factors influencing DAC performance remains limited. This review systematically explores the structure of DAC, addressing key macroscopic parameters, such as spatial arrangements and interatomic distances, as well as microscopic factors, including local coordination environments and electronic structures. Additionally, metal-support interactions (MSI) and long-range interactions (LSI) are comprehensively analyzed, which play a pivotal yet underexplored role in governing DAC behavior. the integration of tailored functional groups is further discussed to fine-tune DAC properties, thereby optimizing intermediate adsorption, enhancing reaction kinetics, and expanding their multifunctionality in various electrochemical environments. This review offers novel insights into their rational design by elucidating the intricate mechanisms underlying DACs' exceptional performance. Ultimately, DACs are positioned as critical players in precision catalysis, highlighting their potential to drive significant breakthroughs across a broad spectrum of catalytic applications.

Multi-Enzyme Mimetic MoCu Dual-Atom Nanozyme Triggering Oxidative Stress Cascade Amplification for High-Efficiency Synergistic Cancer Therapy

Single-atom nanozymes (SAzymes) with ultrahigh atom utilization efficiency have been extensively applied in reactive oxygen species (ROS)-mediated cancer therapy. However, the high energy barriers of reaction intermediates on single-atom sites and the overexpressed antioxidants in the tumor microenvironment restrict the amplification of tumor oxidative stress, resulting in unsatisfactory therapeutic efficacy. Herein, we report a multi-enzyme mimetic MoCu dual-atom nanozyme (MoCu DAzyme) with various catalytic active sites, which exhibits peroxidase, oxidase, glutathione (GSH) oxidase, and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase mimicking activities. Compared with Mo SAzyme, the introduction of Cu atoms, formation of dual-atom sites, and synergetic catalytic effects among various active sites enhance substrate adsorption and reduce the energy barrier, thereby endowing MoCu DAzyme with stronger catalytic activities. Benefiting from the above enzyme-like activities, MoCu DAzyme can not only generate multiple ROS, but also deplete GSH and block its regeneration to trigger the cascade amplification of oxidative stress. Additionally, the strong optical absorption in the near-infrared II bio-window endows MoCu DAzyme with remarkable photothermal conversion performance. Consequently, MoCu DAzyme achieves high-efficiency synergistic cancer treatment incorporating collaborative catalytic therapy and photothermal therapy. This work will advance the therapeutic applications of DAzymes and provide valuable insights for nanocatalytic cancer therapy.

Asymmetric Microenvironment Tailoring Strategies of Atomically Dispersed Dual-Site Catalysts for Oxygen Reduction and CO2 Reduction Reactions

Dual-atom catalysts (DACs) with atomically dispersed dual-sites, as an extension of single-atom catalysts (SACs), have recently become a new hot topic in heterogeneous catalysis due to their maximized atom efficiency and dual-site diverse synergy, because the synergistic diversity of dual-sites achieved by asymmetric microenvironment tailoring can efficiently boost the catalytic activity by optimizing the electronic structure of DACs. Here, this work first summarizes the frequently-used experimental synthesis and characterization methods of DACs. Then, four synergistic catalytic mechanisms (cascade mechanism, assistance mechanism, co-adsorption mechanism and bifunction mechanism) and four key modulating methods (active site asymmetric strategy, transverse/axial-modification engineering, distance engineering and strain engineering) are elaborated comprehensively. The emphasis is placed on the effects of asymmetric microenvironment of DACs on oxygen/carbon dioxide reduction reaction. Finally, some perspectives and outlooks are also addressed. In short, the review summarizes a useful asymmetric microenvironment tailoring strategy to speed up synthesis of high-performance electrocatalysts for different reactions.