Crystalline-Amorphous Interfaces Coupling of CoSe2 /CoP with Optimized d-Band Center and Boosted Electrocatalytic Hydrogen Evolution

Phase-engineered metal boride nanobeads for highly efficient oxygen evolution

Non-precious metals with tailored phase structures show promise as oxygen evolution reaction (OER) catalysts due to their high inherent catalytic activity and extensive exposed active surface area. However, the mechanisms by which phase structures enhance catalytic performance remain unclear. Herein, we synthesized an amorphous cobalt boride (CoB) catalyst via a magnetic field-assisted method, yielding uniform nanoparticles that self-assemble into a nanobead structure. This material undergoes heat treatment to transition from an amorphous phase to a crystalline phase. The catalyst demonstrated exceptional OER activity and long-term stability in an alkaline electrolyte, requiring only 350 mV overpotential at 10 mA cm-2. The amorphous CoB demonstrates remarkable durability by maintaining stable operation for 100 h under harsh conditions characterized by high alkalinity and elevated temperature without any observable performance degradation. We demonstrate that electrochemical activation of an amorphous catalyst can unveil active sites within the bulk material, leveraging the short-range order characteristic of amorphous structures. This process significantly amplifies the active site density, consequently enhancing the electrocatalytic performance of the amorphous catalyst in the oxygen evolution reaction within water oxidation. Furthermore, in situ Raman spectroscopy reveals that amorphous CoB rapid self-reconstruction upon electrochemical activation, leading to the formation of a metal (oxy)hydroxide active layer. This study offers valuable insights into the design of high-efficiency OER catalysts by elucidating the mechanisms underlying amorphous and crystalline materials.

Enhancing Built-In Electric Field via Balancing Interfacial Atom Orbit Hybridization at Boride@Sulfide Heterostructure for Hydrogen Evolution Reaction

Exploring nonprecious metal-based catalysts for cathodic hydrogen evolution reaction (HER) has facilitated the realization of hydrogen economy toward water electrolysis in alkaline media. However, the difficult water dissociation process for the Volmer step (H2O → H* + OH*) and the subsequent unsuitable OH* adsorption energy on nonprecious metal-based catalysts severely reduce the kinetics of HER. Herein, the universal synthesis for a series of transition metal (Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W)-based boride@sulfide heterostructured catalysts is realized by using the molten-salt method to conduct the in situ boronization of commercial sulfides. Significantly, WB2@WS2 heterostructured catalyst exhibits excellent catalytic activity and stability for HER. Balancing interfacial atom orbit hybridization between W(d)-B(s,p) and W(d)-S(s,p) at WB2@WS2 heterostructured interface enhances the built-in electric field. In situ Raman spectroscopy and density functional theory calculation results reveal that the strong built-in electric field in WB2@WS2 optimizes the adsorption and desorption of OH* intermediate, reducing the energy barrier of the rate-determining step (OH* desorption step), and thus favoring the enhancement of catalytic performance toward HER.

Ru doping induces phase transition and in-plane S-site electronic modulation in ternary MoS2 heterostructures to enhance hydrogen evolution in water/seawater

Optimizing the performance of in-plane S atoms of MoS2 is crucial to extend the breadth of application of MoS2. Herein, using a simple hydrothermal method, we prepared a novel electrocatalyst of Ru incorporated into trinary-MoS2 (Ru-MoS2) nanoflowers. Ru doping could promote preferential transition from the semiconducting (2H) phase to the metallic (1T and 1T') phase in the basal plane. Density functional theory (DFT) calculations confirmed that Ru incorporated into MoS2 could optimize the electronic structure, improve the conductivity and optimize H* adsorption in interfacial S sites of trinary-MoS2, and facilitate the catalytic hydrogen evolution activity. Moreover, in-plane S sites on the Ru doping 2H/1T' heterostructure have been shown to be highly active sites for trinary-MoS2. Benefiting from the good conductivity and activated interfacial S sites in trinary-MoS2, the prepared Ru-MoS2 exhibited superior electrocatalytic activity at 10 mA cm-2 and only required overpotentials of 89 mV and 112 mV in alkaline solution and alkaline seawater, respectively. This work provides a fresh insight into the design of highly-efficient trinary-MoS2 electrocatalysts.

Rapid synthesis of metastable materials for electrocatalysis

Metastable materials are considered promising electrocatalysts for clean energy conversions by virtue of their structural flexibility and tunable electronic properties. However, the exploration and synthesis of metastable electrocatalysts via traditional equilibrium methods face challenges because of the requirements of high energy and precise structural control. In this regard, the rapid synthesis method (RSM), with high energy efficiency and ultra-fast heating/cooling rates, enables the production of metastable materials under non-equilibrium conditions. However, the relationship between RSM and the properties of metastable electrocatalysts remains largely unexplored. In this review, we systematically examine the unique benefits of various RSM techniques and the mechanisms governing the formation of metastable materials. Based on these insights, we establish a framework, linking RSM with the electrocatalytic performance of metastable materials. Finally, we outline the future directions of this emerging field and highlight the importance of high-throughput approaches for the autonomous screening and synthesis of optimal electrocatalysts. This review aims to provide an in-depth understanding of metastable electrocatalysts, opening up new avenues for both fundamental research and practical applications in electrocatalysis.

Accelerated photo-Fenton degradation of ciprofloxacin on CoSx@TiO2 amorphous-crystalline interface with S-O bond bridging

Photo-Fenton reaction integrates the benefits of photocatalysis with traditional Fenton chemistry, producing highly reactive hydroxyl radicals for oxidizing organic pollutants into CO2 and H2O. In this study, a unique and novel interface was constructed between amorphous CoSx (cobalt sulfide) and crystalline anatase TiO2 (titanium dioxide): ultra-thin CoSx nanoflakes were directly deposited onto TiO2 nanowires. S-O bonds formed between CoSx and TiO2 establish pathways for the orderly transfer of electrons along the heterojunction interface, facilitating in-situ generation of H2O2 and realizing the high photo-Fenton activity for degrading ciprofloxacin. Under optimal conditions, the elimination rate of ciprofloxacin can reach 100 % within 100 min, and the CoSx@TiO2 composite demonstrates sustained catalytic performance over eight consecutive cycles. Density Functional Theory (DFT) calculations results confirm that CoSx@TiO2 exhibits a more favorable free energy profile compared to single TiO2 during the oxidation of water to produce ∗OH radicals. Under irradiation, integrating CoSx and TiO2 contributes mostly to generate abundant ‧OH radicals. This research provides innovative insights into optimizing photo-Fenton performance by strategically designing amorphous-crystal interfaces connected via electron-conducting bridges.

Constructing Palladium-Based Crystalline@Amorphous Core-Shell Heterojunctions for Efficient Formic Acid Oxidation

Constructing crystalline@amorphous heterostructures allows nanomaterials to maintain high electrical conductivity of crystalline structures while acquiring abundant active sites from amorphous structure. This emerging strategy has attracted considerable attention in electrochemical and photoelectrochemistry applications. However, achieving crystalline@amorphous heterostructures based on palladium (Pd) remains challenging due to the difficulties in balancing the transformation between these two phases. Here, a feasible strategy is developed to manufacture Pd-based crystalline@amorphous core-shell structures through non-metallic element doping. The obtained core-shell structures exhibit outstanding catalytic performance for formic acid oxidation (FAO) with mass activity of up to 2.503 A mg-1 Pd. Detailed theoretical and experimental analyses reveal that the construction of crystalline@amorphous core-shell structures increase surface active sites, lowers the oxidation energy barrier, and enhances the selectivity of the direct pathway, thereby effectively facilitating the FAO process. This work demonstrates the feasibility of constructing efficient FAO catalysts using crystalline@amorphous core-shell structures and provides a new platform for achieving platinum-group metals (PGMs) based crystalline-amorphous heterostructures.

Electron rearrangement at the crystalline-amorphous heterogeneous interface boosts alkaline hydrogen production

Modifying the platinum (Pt) local reaction microenvironment is a critical and complex challenge in enhancing electrochemical performance. Herein, amorphous Co(OH)2 and crystalline Pt (labeled as ac-Pt@Co(OH)2) featuring abundant crystalline-amorphous (c-a) interfaces are designed to boost the hydrogen evolution reaction (HER). The engineered structure creates an advantageous chemical environment at the local level, enhancing hydrogen adsorption efficiency and resulting in exceptional HER performance. The ac-Pt@Co(OH)2 achieves a low Tafel slope of 28.5 mV dec-1 and requires merely 95 mV overpotential to reach 200 mA cm-2 in alkaline electrolyte (1 M KOH), surpassing those of conventional Pt/C catalysts (39.4 mV dec-1, 256 mV). In situ advanced characterization investigations reveal dynamic electron rearrangement at the c-a interface, where Co species initially accept electrons from Pt to optimize the adsorption of *H species and then donate electrons to Pt for accelerating reduction kinetics. Theoretical calculations reveal that amorphous Co(OH)2 promotes the dissociation of water molecules to produce active *H, and electron rearrangement at the c-a interface downshifts the d-band center, thereby optimizing the *H adsorption strength and enhancing HER activity. The ac-Pt@Co(OH)2-based alkaline anion-exchange membrane water electrolyzer (AEMWE) maintains a current density of 500 mA cm-2 over 500 h.

Boosting Oxygen Electrocatalysis in CoN-CoSe2 Heterogeneous Hollow Nanocages with Engineered Build-In Electric Field for Zn-Air Batteries

The exploration of oxygen catalyst with superior behaviors in a wide temperature range is a key issue for Zn-air battery. Herein, the CoN-CoSe2@C hollow cages with a built-in electric field (BIEF) on heterointerface are explored as the oxygen electrocatalyst for Zn-air battery (ZAB). Based on the theoretical analysis, the large work function difference (∆WF) of CoN-CoSe2 heterostructure propels the interfacial electron redistribution, which results in the strong BIEF and facilitates high catalytic activities. In addition, the CoN-CoSe2 nanocrystals are embedded in the hollow carbon nanocage to fully realize its performance. The central hollow structure of the carbon based nanocages provides the facile electron/ion/mass pathways and endows fast kinetics. Taking the advantages of both the strong BIEF and the well-designed substrate, the CoN-CoSe2@C hollow cages achieve the superior bifunctional electrocatalytic behaviors and good cycling performance even down to low-temperature such as -30 °C. Moreover, the full ZAB with CoN-CoSe2@C hollow cage cathode shows the superior performance and high reliability in diverse working conditions. Therefore, it is a promising power source candidate for the electronics in practical applications.

Single-Atom Sb-Doped RuSbOx Bifunctional Catalysts for Ultra-Stable PEM Water Electrolyzers

Developing highly efficient and stable Pt/Ir-free bifunctional catalysts is very urgent for lowering the catalyst cost of proton exchange membrane water electrolyzer (PEMWE). Herein, a single-atom Sb-doped RuSbOx bifunctional catalyst is developed for ultra-stable PEMWE. RuSbOx exhibits excellent stability with a long-term operation of 150 h for oxygen evolution reaction (OER) and 300 h for hydrogen evolution reaction (HER) at 100 mA cm-2 in acidic media, respectively. Impressively, the PEMWE with RuSbOx as bifunctional catalysts only needs 1.72 to reach 1.0 A cm-2, and can maintain stable operation for 200 h at 200 mA cm-2. The in situ Raman and molecular probe methods reveal that the single-atom Sb doping can reconstruct the interfacial water structure on the surface of RuSbOx, resulting in an enriched supply of free water, accelerating the deprotonation process and reducing the local acidity of the catalyst surface, thereby improving the acidic OER activity and stability. Density functional theory calculations further confirm the above experimental results. In short, this work reveals that Sb is an outstanding structural stabilizer, and single-atom Sb-doping can maximize the OER stability of Ru-based catalysts in acid, which provides a useful strategy for designing ultra-stable electrocatalysts for PEMWE.

The Improved Covalent Coupling Induced by Bi Cations in CoBiSex Nanosheet Arrays for Stable Water Electrolysis

Transition metal selenides (TMSes) with high electrical conductivity, easily regulated morphological structure, and unique electronic structure have been explored as promising electrocatalysts for electrolytic water, while the lower intrinsic electrocatalytic capability has limited their wide application. Herein, we obtained CoSe nanosheet arrays with Bi cations incorporation (CoBiSex nanosheet arrays) driven by spinel oxides. Compared with spinel oxides, the low electronegativity of Se in CoBiSex nanosheet arrays leads to a portion of Co2+ in the low spin states (t2g6eg1) due to the high covalent interaction between Co and Se, which can facilitate charge transfer. Density functional theory (DFT) calculation results further identify the redistribution of electron density from Se to Co, intensifying the adsorption of OOH* during the electrolytic water process with a 140 h robust catalytic performance. This work offers a unique strategy for exploring TMSe materials and their potential applications in the electrolytic water process.

Negative-Valent Platinum Stabilized by Pt─Ni Electron Bridges on Oxygen-Deficient NiFe-LDH for Enhanced Electrocatalytic Hydrogen Evolution

The unique hydrogen adsorption characteristics of negatively charged platinum play a crucial role in enhancing the electrocatalytic hydrogen evolution reaction. However, atomically dispersed Pt atoms are typically anchored to the support through non-metallic atom bonds, resulting in a high oxidation state. Here, atomically dispersed Pt atoms are anchored in oxygen-deficient NiFe-LDH. Electron transfer between Pt and NiFe-LDH occurs primarily through Pt─Ni bonds rather than the conventional Pt─O bonds. Oxygen vacancies in the NiFe-LDH promote additional electron transfer from Ni to Pt, thereby reducing the valence state of Pt and enhancing hydrogen adsorption. Meanwhile, the elevated valence state of Ni increases the catalyst's hydrophilicity and reduces the energy barrier for hydrolysis dissociation. This catalyst demonstrates remarkably low overpotentials of 4 and 9 mV at 10 mA cm-2 in 1 m KOH and 1 m KPi, respectively. Additionally, its mass activity is 51.5 and 23.7 times higher that of Pt/C, respectively. This study presents a novel strategy for enhancing electrocatalytic performance through the rational design of coordination environments and electronic structures in supported metal catalysts.

Heteroatom Introduction and Electrochemical Reconstruction on Heterostructured Co-Based Electrocatalysts for Hydrogenation of Quinolines

Electrocatalytic hydrogenation (ECH) of quinoline provides an eco-friendly and prospective route to achieve the highly value-added generation of 1,2,3,4-tetrahydroquinoline (THQ). Co element has been proven to be the efficient catalytic site for ECH of quinoline, but the rational regulation of the electronic structure of active Co site to improve the activity is still a challenge. Herein, the hierarchical core-shell structure consisting of NiCo-MOF nanosheets encapsulated Cu(OH)2 nanorods (Cu(OH)2@CoNi-MOF) is constructed. The heterojunction promotes the transfer of interfacial charge and optimizes the electronic structure of the Co site. The introduction of Ni significantly increases the binding between Co and Cu, preventing the exfoliation of Co sites from Cu(OH)2 core, and reducing the reaction energy barrier of rate-determining step, thus resulting in superior reactivity and durability. Besides, electrochemical reconstruction further modulates the electronic structure of Co by forming the multi-metallic compound with a low valence state (NiCoCu), achieving an optimal performance with a conversion of 99.5% and THQ selectivity of 100%. A flow-cell system is assembled, demonstrating the prospect for industrial application.

Crystalline CoP@ Amorphous WP2 Coaxial Nanowire Arrays as Bifunctional Electrocatalyst for Water Splitting

The crystalline CoP@ amorphous WP2 core-shell nanowire arrays are oriented grown on the Ni foam (CoP@WP2/NF). The amorphous WP2 shell provides more active sites, and the interface charge coupling accelerates the kinetic of the catalytic reaction, making the CoP@WP2/NF catalysts excellent activity. In acidic, only 13 and 97 mV overpotentials are needed to reach 10 mA cm-2 and 100 mA cm-2, respectively, which are the lowest overpotentials among all reported Transition metal phosphide (TMP) catalysts, of course, much lower than that of the Pt/C catalyst (31 mV at 10 mA cm-2, 120 mV at 100 mA cm-2). In alkaline, the Hydrogen evolution reaction (HER) overpotentials at 10 mA cm-2 and 100 mA cm-2 are 68 and 136 mV, respectively, which are also lower than that of most reported TMPs catalysts. The CoP@WP2/NF catalysts also show excellent Oxygen evolution reaction (OER) performance in alkaline, and its OER overpotential at 10 mA cm-2 is only 254 mV. The voltage of the CoP@WP2/NF-2h‖CoP@WP2/NF-2 h cell is only 1.37 V at 10 mA cm-2, which is even lower than that of Pt/C‖Ru2O cell (1.52 V). Specially, when the current density is greater than 150 mA cm-2, the energy consumption advantage of the CoP@WP2/NF-2 h‖CoP@WP2/NF-2 h cell is more obvious.

Tailoring the Catalytic Activity of Metal Catalysts by Laser Irradiation

In recent years, the rapid advancements in laser technology have garnered considerable interest as an efficient method for synthesizing electrocatalytic nanomaterials. This review delves into the progress made in laser-induced nanomaterials for electrocatalysis, providing a comprehensive overview of the synthesis strategies and catalytic mechanisms involved in defect engineering, morphology tuning, and heterostructure formation. The review highlights the various laser-induced synthesis techniques in producing nanomaterials with enhanced electrocatalytic properties. It discusses the underlying mechanisms through which laser irradiation can induce defects, modify morphology, and create heterostructures in nanomaterials, ultimately leading to improved catalytic performance. The comprehensive summary of these synthesis strategies and catalytic mechanisms provides valuable insights for researchers interested in utilizing laser technology for the fabrication of advanced electrocatalytic materials. Furthermore, this review identifies the existing challenges and outlines future directions within this booming research field. By addressing the current limitations and discussing potential avenues for exploration, the review provides important guidance for researchers looking to design and fabricate laser-induced nanomaterials with desirable properties for advanced electrocatalysis and beyond.

Cascade Reaction Enables Heterointerfaces-Enriched Nanoarrays for Ampere-Level Hydrogen Production

Designing high-performance electrocatalysts with superior catalytic activity and stability is essential for large-scale hydrogen production via water electrolysis. Heterostructure nanoarrays are promising candidates, though achieving both high activity and stability simultaneously, especially under high current densities, remains challenging. To this end, we have developed a cascade reaction process that constructs a series of heterostructure nanoarrays with rich heterointerfaces. This process involves treating nickel foam (NF) with molten KSCN and transition metal salts. Initially, NF reacts with KSCN to form Ni9S8 nanoarrays and S2- ions, which are subsequently captured by transition metal ions to form sulfides that are directly integrated onto the nanoarrays, resulting in abundant heterointerfaces. Both experimental and theoretical results indicate that these rich heterointerfaces significantly enhance the interfacial interaction between Ni9S8 and RuS2 within the nanoarrays (termed RH-Ni9S8/RuS2), markedly improving both the intrinsic activity and stability for the hydrogen evolution reaction (HER). Impressively, the RH-Ni9S8/RuS2 demonstrates exceptional HER performance, achieving a low overpotential of just 180 mV at 1000 mA cm-2 and maintaining stability for up to 500 h under such high-current-density conditions. This innovative approach paves the way for the interfacial design and synthesis of high-performance catalysts for ampere-level hydrogen production.

Amorphous Pd nanoparticles inside ethylenediamine-based nanocomposite for high N2-selectivity of nitrate reduction

Catalytic reduction of nitrate to dinitrogen (N2) by noble metals stands as a feasible and promising manner to address the biological and environmental issues associated with nitrate pollution; however, nitrate reduction under single noble-metal catalyzation remains substantially stuck because of the low adsorption enthalpy of noble metal toward nitrate. Tailoring the formation (crystal structure and particle size) of catalytical metal particles, coupled with a more direct electron donating pattern, provides a potential solution for the main challenge in reduction efficiency and selectivity. In this study, we assembled a Pd-based nanocomposite (Pda@EC) by subtly regulating the embedded Pd nanoparticles inside a porous substrate self-sufficient in electron donator (i.e., ethylenediamine group, EDA). Without any provision of reductant, the resultant single-metal catalyst demonstrated excellent nitrate catalytic reduction with over 95 % of N2 reduction selectivity within very broad pH range (3-11), whereas its unregulated counterpart (crystal Pd nanocomposite, Pdc@EC) is incapable of efficient nitrate reduction under otherwise identical conditions. The activated hydrogen (H*), which was exclusively yielded under the catalyzation of the amorphous Pd nanoparticles for the electron donating EDA, was confirmed as the primary active species, and the high N2 selectivity is attributed to the cooperation between EDA and Pd nanoparticles. More promisingly, the exhausted Pda@EC is amenable to effective regeneration with mild NaOH (elution) and NaBH4 (restoration) treatment. This work provides an effective strategy for selectively reducing nitrate under monometallic catalyzation by subtly regulating the crystal structure of Pd nanoparticles in endogenous electron-donating environment.

Electronic Engineering of Crystalline/Amorphous CoP/FeCoPx Nanoarrays for Efficient Water Electrolysis

The development of bifunctional, non-noble metal-based electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) through morphology and electronic engineering is highly attractive for efficient water splitting. Herein, hierarchical nanoarrays consisting of crystalline cobalt phosphide nanorods covered by amorphous Fe-doped cobalt phosphide nanocuboids (CoP/FeCoPx) are constructed as bifunctional catalysts for both HER and OER. Experimental results and theoretical calculations reveal that the catalysts exhibit balanced dual-catalytic properties due to simultaneous introduction of Fe doping and phosphorus vacancies, leading to an optimized electronic structure of the CoP/FeCoPx. Furthermore, the hierarchical nanoarrays made of crystalline/amorphous heterostructures significantly enhance the performance of the electrocatalysts. As a result, the CoP/FeCoPx catalyst demonstrates remarkable performance in both HER and OER, with overpotentials of 74 and 237 mV at 10 mA cm-2 in 1 m KOH, respectively, as well as a low cell voltage of 1.53 V at 10 mA cm-2 for alkaline overall water splitting. This work integrates the morphology engineering involving design of hierarchical crystalline/amorphous nanoarrays and the electronic engineering through Fe doping and phosphorus vacancies for efficient water electrolysis. It may open a new route toward rational design and feasible fabrication of high-performance, multifunctional, non-noble metal-based electrocatalysts for energy conversion.

Achieving advanced hydrogen evolution under large current density using an amorphous/crystalline core-shell electrocatalyst of a-NiCoP/Co2P

Non-precious transition metal-based electrocatalysts with high activities are promising candidates for substituting Pt- or Ru-based electrocatalysts in hydrogen evolution. In this study, we propose core-shell engineering to combine the amorphous NiCoP and crystalline Co2P (a-NiCoP/Co2P@NF), which requires an ultra-low overpotential of only 26 mV to achieve the benchmark current density of 10 mA cm-2. Furthermore, it achieves an industrial-level hydrogen evolution current density of 500 mA cm-2 with excellent stability. The superior catalytic performance and stability can be attributed to the hierarchical amorphous/crystalline interface and the electron-rich interfacial Co sites. The amorphous NiCoP shell can not only protect the internal Co2P from corrosion, but also provide a larger electrochemically active area. Together, the Co2P core provides fast electron transport and promotes H2 emission from the interfacial electron-rich Co sites. This work provides inspiration to the rational design of an advanced core-shell structure between amorphous and crystalline states.

What Is the Mechanism by which the Introduction of Amorphous SeOx Effectively Promotes Urea-Assisted Water Electrolysis Performance of Ni(OH)2?

Nickel hydroxide (Ni(OH)2) is considered to be one of the most promising electrocatalysts for urea oxidation reaction (UOR) under alkaline conditions due to its flexible structure, wide composition and abundant 3D electrons. However, its slow electrochemical reaction rate, high affinity for the reaction intermediate *COOH, easy exposure to low exponential crystal faces and limited metal active sites that seriously hinder the further improvement of UOR activities. Herein it is reported electrocatalyst composed of rich oxygen-vacancy (Ov) defects with amorphous SeOx-covered Ni(OH)2 (Ov-SeOx/Ni(OH)2). Surprisingly, at 100 mA cm-2, compared with Ni(OH)2 (1.46 V (vs RHE)), Ov-SeOx/Ni(OH)2 has a potential of 1.35 V. Meanwhile, Ov-SeOx/Ni(OH)2 catalyst also showed good hydrogen evolution reaction (HER) performance, so it is used as the electrolytic cell assembled by UOR and HER bifunctional catalysts and only 1.57 V could reach 100 mA cm-2. Density functional theory (DFT) study revealed that introduce of amorphous SeOx optimizes the electronic structure of the central active metal, amorphous/crystalline interfaces promote charge-carrier transfer, shift d-band center and entail numerous spin-polarized electrons during the reaction, which speeds up the UOR reaction kinetics.

1D Co6Mo6C-Based Heterojunctional Nanowires from Pyrolytically "Squeezing" PMo12/ZIF-67 Cubes for Efficient Overall Water Electrolysis

The bi-transition-metal interstitial compounds (BTMICs) are promising for water electrolysis. The previous BTMICs are usually composed of irregular particles. Here, this work shows the synthesis of novel 1D Co6Mo6C-based heterojunction nanowires (1D Co/Co6Mo6C) with diameters about 50 nm and a length-to-diameter ratio about 20 for efficient water electrolysis. An interesting growth process based on pyrolytically "squeezing" PMo12 (Phosphomolybdic acid)/ZIF-67 (Zeolitic Imidazolate Framework-67) cube precursor is demonstrated. The "squeezing" growth is related to the role of Mo species for isolating Co species. A series of tests and theoretical calculation show the mutual regulation of Co and Mo to optimize the electronic structure, accelerating H2O dissociation and the reduction kinetics of H+. Additionally, the nanowires provide pathways for electron transfer and the transmission of reactants. Consequently, the 1D Co/Co6Mo6C exhibits high activity for hydrogen evolution reaction (η10 of 31 mV) and oxygen evolution reaction (η10 of 210 mV) in 1 m KOH. The electrolytic cell based on 1D Co/Co6Mo6C requires a low voltage of 1.43 V to drive 10 mA cm-2. The catalyst also exhibits good HER performance in 1 m phosphate-buffered saline solution, exceeding Pt/C at a current density >42 mA cm-2.

Interface-Driven Catalytic Enhancements in Nitrogen-Doped Carbon Immobilized CoNi2S4@ReS2/CC Heterostructures for Optimized Hydrogen and Oxygen Evolution in Alkaline Seawater-Splitting

The rational design of multicomponent heterostructure is an effective strategy to enhance the catalytic activity of electrocatalysts for water and seawater electrolysis in alkaline conditions. Herein, MOF-derived nitrogen-doped carbon/nickel-cobalt sulfides coupled vertically aligned Rhenium disulfide (ReS2) on carbon cloth (NC-CoNi2S4@ReS2/CC) are constructed via hydrothermal and activation approaches. Experimental and theoretical analysis demonstrates that the strong interactions between multiple interfaces promote electron redistribution and facilitate water dissociation, thereby optimizing *H adsorption energy for the hydrogen evolution reaction (HER). Meanwhile, the adsorption energies of oxygenated intermediates are balanced to reduce the thermodynamic barrier for the oxygen evolution reaction (OER). Consequently, NC-CoNi2S4@ReS2/CC shows smaller overpotentials of 87 and 253 mV for HER and OER at 10 mA cm-2, with a lower Tafel slope and Rct than control samples. Superior catalytic stability is confirmed by cyclic voltammetry (CV) for 1000 cycles and CA test for 56 h. Furthermore, NC-CoNi2S4@ReS2/CC presents exceptional electrocatalytic activity in both alkaline water/seawater electrolytes. Stability assessments reveal that NC-CoNi2S4@ReS2/CC maintains a highly catalytic activity in both water and seawater, owing to the corrosion-resistant properties of the sulfur species at the interface. These findings highlight the importance of designing heterostructure electrocatalysts for clean hydrogen production.

Porous Amorphous-Crystalline Heterostructured CoNiP Nanowire Arrays for Enhanced Hydrogen Evolution Performance under Acid-Base Conditions

A novel porous amorphous-crystalline heterostructured CoNiP nanowire arrays ((a-c)CoNiP/CC) is presented. TEM observations and compositional calculations revealed ≈14.5% of the amorphous regions (a-CoNiP) are interleaved in the crystalline regions (c-(Co3.6Ni0.4)P4), forming massive amorphous-crystalline heterogenous interfaces composed of the same elements. Only 38 and 64 mV overpotentials for the (a-c)CoNiP/CC catalyst are required to reach the current density of -10 mA cm2 in acid and alkaline electrolyte, respectively, which is very close to the overpotentials (35 and 55 mV) of the commercial Pt/C HER catalyst. The theoretical calculation revealed that the (a-c)CoNiP/CC has a completely different enhancement mechanism of HER reaction in acid-base electrolytes. In particular, due to the natural corrosion resistance of the amorphous interface, the HER performance of this catalyst under the high current density condition is much better than that of the Pt/C catalyst either in acidic or in alkaline, suggesting its prospect for commercial applications.

Synergistic effects of interface and phase engineering on telluride toward alkaline/neutral hydrogen evolution reaction in freshwater/seawater

The development of efficient, stable, and versatile hydrogen evolution electrocatalysts is of great meaning, but still faces challenging. Interface engineering and phase engineering have been immensely applied in the field of hydrogen evolution reaction (HER) because of their unique physicochemical properties. However, they are typically used separately, which limits their effectiveness. Herein, we propose an interface-engineered CoMo/CoTe electrocatalyst, consisting of an amorphous CoMo (a-CoMo) layer-encapsulated crystalline CoTe array, achieving the profound optimization of catalytic performance. The experimental results and density functional theory calculations show that the d-band center of the catalyst shifts further upward in contrast with its crystalline-crystalline counterpart, optimizing the electronic structure and the intermediate adsorption, thereby reducing the kinetic barrier of HER. The a-CoMo/CoTe with superhydrophilic/superaerophobic features shows excellent catalytic performance in alkaline, neutral, and simulated seawater environments.

Modulating the D-Band Center of Electrocatalysts for Enhanced Water Splitting

To tackle the global energy scarcity and environmental degradation, developing efficient electrocatalysts is essential for achieving sustainable hydrogen production via water splitting. Modulating the d-band center of transition metal electrocatalysts is an effective approach to regulate the adsorption energy of intermediates, alter reaction pathways, lower the energy barrier of the rate-determining step, and ultimately improve electrocatalytic water splitting performance. In this review, a comprehensive overview of the recent advancements in modulating the d-band center for enhanced electrocatalytic water splitting is offered. Initially, the basics of the d-band theory are discussed. Subsequently, recent modulation strategies that aim to boost electrocatalytic activity, with particular emphasis on the d-band center as a key indicator in water splitting are summarized. Lastly, the importance of regulating electrocatalytic activity through d-band center, along with the challenges and prospects for improving electrocatalytic water splitting performance by fine-tuning the transition metal d-band center, are provided.

Partially Amorphous Ru-Doped CoSe Nanoparticles with Optimized Intermediates Adsorption for Highly Efficient Sulfur Oxidation Reaction

The application of thermodynamically more favorable sulfur oxidation reaction (SOR) to replace oxygen evolution reaction (OER) in electrocatalytic water electrolysis is an appealing strategy to achieve low-energy hydrogen production while removing toxic sulfur ions from wastewater. However, the study of SOR catalysts with both activity and stability still faces great challenges. Herein, this study prepares partially amorphous Ru-doped CoSe (pa-Ru-CoSe) nanoparticles for SOR. The doping of Ru keeps Co in an electron-deficient state, which enhances the adsorption of SOR intermediates and improves the catalytic activity. Meanwhile, the partially amorphous selenide possesses great corrosion resistance to sulfur species, thus ensuring stability in long-term SOR. In addition, the pa-Ru-CoSe requires only 0.566 V to reach a current density of 100 mA cm-2 in the SOR-HER coupled system and remains stable for 200 h. This work provides a promising partially amorphous strategy for SOR catalysts with both catalytic activity and long-term stability, enabling hydrogen production with low energy consumption and simultaneous sulfur production.

Deliberate Amorphization of Co-MOF for Constructing Crystalline-Amorphous Heterostructures Toward High-Performance Water Electrolysis

The endowment of metal organic frameworks (MOF) with superior electrocatalytic performance without compromising their structural/compositional superiorities is of great significance for the development of renewable energy devices, yet remains a grand challenge. Herein, a deliberate partial amorphization strategy is developed to construct a heterostructured electrocatalyst consisting of crystalline Co-MOF and amorphous Co-S nanoflake arrays aligned on the carbon cloth (CC) substrate (abbreviated as Co-MOF/Co-S@CC hereafter) through a rapid sulfuration method. The simultaneous implement of crystalline-amorphous (c-a) heterostructure and nanoflake arrayed architecture on CC substrate renders the Co-MOF/Co-S@CC with abundant and tight active sites, accelerated charge transfer rate, regulated electronic structures, and reinforced structural stability. As such, the obtained Co-MOF/Co-S@CC electrode demonstrates outstanding electrochemical hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) performances with the overpotentials of 64 and 217 mV at 10 mA cm-2, respectively. Moreover, a two-electrode electrolyzer assembled by Co-MOF/Co-S@CC electrodes exhibits the lower cell voltages and larger current densities than those of Pt/C and RuO2 counterparts, excellent reversibility and prominent long-term stability, representing a great prospect for feasible H2 production. This adopted concept of c-a heterostructure for electronic regulation may bring about insightful inspiration for designing high-performance electrocatalysts for sustainable energy systems.

Developing Rapid-Charging Li-S Batteries via "Target Catalysis" of Cations and Anions Modified Electrocatalyst

The shuttle effect and sluggish sulfur reduction reaction have resulted in significantly low efficiency and poor high current cycling stability in lithium-sulfur batteries, impeding their practical applications. To address these challenges, the introduction of Ni cations into MoS2 grown on reduced graphene oxide (MoS2/rGO) induces the formation of impurity energy levels between the conduction and valence bands of MoS2. Additionally, the introduction of anionic Se expands the interlayer spacing, enhances intrinsic conductivity, and improves ion diffusion rates. Simultaneously introducing anionic and cationic species into the MoS2/rGO causes the center of the d-band to shift upward, reducing the occupancy of electrons in antibonding orbitals. This modification leads to a rearrangement of the electronic structure of Mo, accelerating the redox reactions of lithium polysulfides. It particularly enhances the binding energy and lowers the conversion energy barrier of Li2S4. Consequently, the Li||S coin cell with the Ni-MoSSe/rGO cathode demonstrates an initial capacity of 446 mAh g-1 at 20 C, with a remarkable capacity retention of ≈96.7% after 200 cycles. Moreover, even under high sulfur loading conditions (6.45 mg cm-2) and a low electrolyte/sulfur ratio (5.4 µL mg-2), it maintains a high areal capacity of 6.42 mAh cm-2.

S-S Bond Strategy at Sulfide Heterointerface: Reversing Charge Transfer and Constructing Hydrogen Spillover for Boosted Hydrogen Evolution

Developing efficient electrocatalyst in sulfides for hydrogen evolution reaction (HER) still poses challenges due to the lack of understanding the role of sulfide heterointerface. Here, we report a sulfide heterostructure RuSx/NbS2, which is composed of 3R-type NbS2 loaded by amorphous RuSx nanoparticles with S-S bonds formed at the interface. As HER electrocatalyst, the RuSx/NbS2 shows remarkable low overpotential of 38 mV to drive a current density of 10 mA cm-2 in acid, and also low Tafel slope of 51.05 mV dec-1. The intrinsic activity of RuSx/NbS2 is much higher than that of Ru/NbS2 reference as well as the commercial Pt/C. Both experiments and theoretical calculations unveil a reversed charge transfer at the interface from NbS2 to RuSx that driven by the formation of S-S bonds, resulting in electron-rich Ru configuration for strong hydrogen adsorption. Meanwhile, electronic redistribution induced by the sulfide heterostructure facilitates hydrogen spillover (HSo) effect in this system, leading to accelerated hydrogen desorption at the basal plane of NbS2. This study provides an effective S-S bond strategy in sulfide heterostructure to synergistically modulate the charge transfer and adsorption thermodynamics, which is very valuable for the development of efficient electrocatalysts in practical applications.

CdS-based Schottky junctions for efficient visible light photocatalytic hydrogen evolution

Heterojunctions photocatalysts play a crucial role in achieving high solar-hydrogen conversion efficiency. In this work, we mainly focus on the charge transfer dynamics and pathways for sulfides-based Schottky junctions in the photocatalytic water splitting process to clarify the mechanism of heterostructures photocatalysis. Sulfides-based Schottky junctions (CdS/CoP and CdS/1T-MoS2) were successfully constructed for photocatalytic water splitting. Because of the higher work function of CdS than that of CoP and 1T-MoS2, the direction of the built-in electric field is from CoP or 1T-MoS2 to semiconductor. Therefore, CoP and 1T-MoS2 can act as electrons acceptors to accelerate the transfer of photo-generated electron on the surface of CdS, thus improving the charge utilization efficiency. Meanwhile, CoP and 1T-MoS2 as active sites can also promote the water dissociation and lower the H+ reduction overpotential, thus contributing to the excellent photocatalytic hydrogen production activity (23.59 mmol·h-1·g-1 and 1195.8 mol·h-1·g-1 for CdS/CoP and CdS/1T-MoS2).

Crystalline-Amorphous IrOx Supported on Perovskite Nanotubes for pH-Universal OER

Designing catalysts with desirable oxygen evolution reaction (OER) performance under pH-universal conditions is of great significance to promote the development of hydrogen production. Herein, we successfully synthesized a crystalline-amorphous IrOx supported on perovskite oxide nanotubes to obtain IrOx@La0.6Ca0.4Fe0.8Ni0.2O3 with superior OER performance in whole pH media. The overpotential of the IrOx@La0.6Ca0.4Fe0.8Ni0.2O3 catalyst in media of pH 14, 7.2, and 1 has been demonstrated to be 120, 400, and 143 mV, respectively, with no significant element dissolution as well as double-layer capacitance decay after the durability test. Through comparative experiments with IrOx@CNT and the physical mixture of IrOx and La0.6Ca0.4Fe0.8Ni0.2O3, it is found that the strong metal-support interaction (SMSI) in IrOx@La0.6Ca0.4Fe0.8Ni0.2O3 makes IrOx exist in an amorphous state rich in Ir3+, which is closely associated with the surface-active species Ir-OH. Through the regulation of Ir by a perovskite oxide support at the heterointerface, the reaction breaks through the limitation of the adsorbate evolution mechanism (AEM) and converts to a lattice-oxygen-mediated mechanism (LOM), which was fully demonstrated by the addition of the probe tetramethylammonium cation (TMA+), a LOM reaction intermediate, to the electrolyte. This work fills the research gap of perovskite oxide supported Ir-based catalysts with heterogeneous structures, providing an excellent strategy for the structural design of efficient pH-universal OER catalysts for hydrogen production systems.

Layered MOF supported on 2D delaminated MXene (Mo2Ti2C3) nanosheets boosted water splitting

Metal organic frameworks (MOFs) have a porous structure, high surface area, and high charge transfer, and they have been regarded as model electrocatalysts. Optimization of the electrocatalytic activity of MOFs is challenging, and an effective strategy for this optimization is the construction of a well-defined interfacial bond bridge. In this work, an in situ approach of composite synthesis is reported for MOF (CoNiNH2BDC) with MXenes (Mo2Ti2C3), as the electrocatalytic properties of MOF can be greatly enhanced with the incorporation of the conductive material MXene. The prepared composite material was characterized thoroughly using XRD, XPS, FESEM, EDX, TEM, and BET. The synergistic effect of both components of this composite material resulted in enhanced conductivity and the number of active sites, which led to enhanced electrocatalytic performance. The CoNiNH2BDC MOF with different ratios of Mo2Ti2C3 MXene were synthesized, and the resulting materials were evaluated for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) activities. It was observed that the MOFMX3 attained a 10 mA cm-2 current density at 1.44 V for OER and -0.037 V for HER (vs. RHE), and lower values of Tafel slopes of 44.8 mV dec-1 for OER and 45 mV dec-1 for HER in 0.1 M KOH were achieved. The higher double layer capacitance (C dl) values lead to high electrochemical surface area (ECSA) values. Lower Tafel slope values for MOFMX3 show that the presence of MXene nanosheets in the hybrid provides support to the layered and porous configuration of MOF, and the chances of the interaction of electrolyte to the catalytically active sites are significantly enhanced. This work highlights the idea of growing bimetallic MOFs on Mo2Ti2C3 MXene using an interdiffusion reaction strategy and opens up an avenue for designing highly electrocatalytic systems.

Unveiling the potential of amorphous nanocatalysts in membrane-based hydrogen production

Hydrogen, as a clean and renewable energy source, is a promising candidate to replace fossil fuels and alleviate the environmental crisis. Compared with the traditional H-type cells with a finite-gap, the design of membrane electrodes can reduce the gas transmission resistance, enhance the current density, and improve the efficiency of hydrogen production. However, the harsh environment in the electrolyser makes the membrane electrode based water electrolysis technology still limited by the lack of catalyst activity and stability under the working conditions. Due to the abundant active sites and structural flexibility, amorphous nanocatalysts are alternatives. In this paper, we review the recent research progress of amorphous nanomaterials as electrocatalysts for hydrogen production by electrolysis at membrane electrodes, illustrate and discuss their structural advantages in membrane electrode catalytic systems, as well as explore the significance of the amorphous structure for the development of membrane electrode systems. Finally, the article also looks at future opportunities and adaptations of amorphous catalysts for hydrogen production at membrane electrodes. The authors hope that this review will deepen the understanding of the potential of amorphous nanomaterials for application in electrochemical hydrogen production, facilitating future nanomaterials research and new sustainable pathways for hydrogen production.

A strongly coupled oxide-support heterostructure for efficient acidic water oxidation

The synthesized RuO2/MnCo2O4.5 nano-heterostructure possesses dense interfaces and abundant defect structures, synergistically balancing oxygen evolution reaction (OER) activity and stability. RuO2/MnCo2O4.5 exhibits a low overpotential of 190 mV at 10 mA cm-2. The proton exchange membrane (PEM) electrolyzer assembled can operate at 200 mA cm-2 stably for 50 h.

Boosted Electrochemical Hydrogen Evolution Activity via the Core-Shell Heterostructure of Nickel Sulfide Nanoframe-Supported Layered Rhenium Disulfide

The strategic design of a heterostructure catalyst with a core-shell nanoarchitecture is imperative for enhancing the efficiency of the electrocatalytic hydrogen evolution reaction (HER). Herein, the core-shell catalyst comprising the rhenium disulfide nanosheets was vertically integrated onto a hollow nickel sulfide (NiS@ReS2) via coprecipitation and hydrothermal treatment. The morphology involves the sulfurization of a nickel-based Prussian blue analogue, effectively mitigating the aggregation of ReS2 nanosheets and maximizing the exposed active sites. By the synergistic effect of morphological design and heterostructure formation, the overpotential of NiS@ReS2 is 136 mV at 10 mA cm-2 in an alkaline electrolyte, and the rapid kinetics is confirmed by the small Tafel slope and low charge transfer resistance during the HER process. Moreover, the electrocatalytic durability of NiS@ReS2 is elucidated, and the boosted catalytic activity of NiS@ReS2 is confirmed by density functional theory. This study unveils a promising method for advancing ReS2-based electrocatalysts with potential implications for producing hydrogen.

Optimal Electrocatalyst Design Strategies for Acidic Oxygen Evolution

Hydrogen, a clean resource with high energy density, is one of the most promising alternatives to fossil. Proton exchange membrane water electrolyzers are beneficial for hydrogen production because of their high current density, facile operation, and high gas purity. However, the large-scale application of electrochemical water splitting to acidic electrolytes is severely limited by the sluggish kinetics of the anodic reaction and the inadequate development of corrosion- and highly oxidation-resistant anode catalysts. Therefore, anode catalysts with excellent performance and long-term durability must be developed for anodic oxygen evolution reactions (OER) in acidic media. This review comprehensively outlines three commonly employed strategies, namely, defect, phase, and structure engineering, to address the challenges within the acidic OER, while also identifying their existing limitations. Accordingly, the correlation between material design strategies and catalytic performance is discussed in terms of their contribution to high activity and long-term stability. In addition, various nanostructures that can effectively enhance the catalyst performance at the mesoscale are summarized from the perspective of engineering technology, thus providing suitable strategies for catalyst design that satisfy industrial requirements. Finally, the challenges and future outlook in the area of acidic OER are presented.

Modulating the Electronic Structure of Cobalt-Vanadium Bimetal Catalysts for High-Stable Anion Exchange Membrane Water Electrolyzer

Modulating the electronic structure of catalysts to effectively couple the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is essential for developing high-efficiency anion exchange membrane water electrolyzer (AEMWE). Herein, a coral-like nanoarray composed of nanosheets through the synergistic layering effect of cobalt and the 1D guiding of vanadium is synthesized, which promotes extensive contact between the active sites and electrolyte. The HER and OER activities can be enhanced by modulating the electronic structure through nitridation and phosphorization, respectively, enhancing the strength of metal-H bond to optimize hydrogen adsorption and facilitating the proton transfer to improve the transformation of oxygen-containing intermediates. Resultantly, the AEMWE achieves a current density of 500 mA cm-2 at 1.76 V for 1000 h in 1.0 M KOH at 70 °C. The energy consumption is 4.21 kWh Nm-3 with the producing hydrogen cost of $0.93 per kg H2. Operando synchrotron radiation and Bode phase angle analyses reveal that during the high-energy consumed OER, the dissolution of vanadium species transforms distorted Co-O octahedral into regular octahedral structures, accompanied by a shortening of the Co-Co bond length. This structural evolution facilitates the formation of oxygen intermediates, thus accelerating the reaction kinetics.

Rich oxygen vacancy and amorphous/crystalline ruthenium-doped CoCu -layered double hydroxide electrocatalysts for enhanced oxygen evolution reactions

Reinforcing the development of efficient and robust electrocatalysts is pivotal in addressing the challenges associated with oxygen evolution reactions (OER) in water splitting technology. Here, an amorphous/crystalline low-ruthenium-doped bimetallic layered double hydroxide (LDH) electrocatalyst (a/c-CoCu + Rux-LDH/NF) with massive oxygen vacancy on nickel foam was fabricated via ion-exchange and chemical etching, facilitating efficient OER. Among the various catalyst materials tested, the a/c-CoCu + Ru10-LDH/NF exhibits remarkable performance in the OER when employed in an alkaline electrolyte containing 1 M KOH. Achieving a minimal overpotential at 10 mA cm-2 of 214 mV, exhibiting a low Tafel slope value of 64.3 mV dec-1 and exceptional durability lasting for over 100 h. Theoretical calculations demonstrate that the electron structure and d-band center of CoCu-LDH can be effectively regulated through the utilization of a strategy possessing abundant oxygen vacancies and a Ru-doped crystalline/amorphous heterostructure. It will lead to optimized adsorption free energy of reactants and reduced energy barriers for OER. The construction strategy proposed in this paper for catalysts with amorphous/crystalline heterointerfaces offer a novel opportunity to achieve highly efficient OER.

Phase-Induced Strain Effect to Synthesize an Iron-Doped Orthogonal Cobalt Selenide Electrocatalyst for the Oxygen Evolution Reaction

The etching effect has the capability to control atom doping and trigger phase transformation, thereby enhancing the electrocatalytic reaction. Herein, iron-doped cobalt selenide (Fe-CoSe2) nanoparticle-decorated carbon nanofibers (Fe-CoSe2/CNFs) are synthesized by assembling an FeCo-Prussian blue analogue (FeCo-PBA) cube precursor with polyacrylonitrile fibers and then treating with hydrochloric acid, followed by gas phase selenization. The Fe-CoSe2/CNFs catalyst exhibits a large surface area and a porous structure, facilitating the permeation of electrolytes. Moreover, orthorhombic CoSe2 is obtained, which is in favor of improving the oxygen evolution reaction (OER). By modulating the etching time, the ideal crystal phase and the optimal amount of the dopant (Fe) can be achieved, thus showing favorable OER activity. Specifically, the Fe-CoSe2/CNFs electrocatalyst enables high electrocatalytic activity for the OER with a low overpotential of 263 mV to drive a current density of 10 mA cm-2 in 1 M KOH. A small Tafel slope of 51 mV dec-1 shows fast charge transfer kinetics. Density functional theory (DFT) calculations reveal that Fe-doped orthorhombic CoSe2(111) can modulate the electron structure, contributing to OH- adsorption ability. Given this, a strategy for phase transformation induced by etching technology is proposed to improve the intrinsic activity of the catalyst.

One Stone, Three-Birds Approach: Ultra-active Ru/N, S-MoO2/CNTs Electrocatalyst for Overall Water Splitting in Wide Electrode Applications (NF, GC, and CC)

The construction of exceptionally multifunctional electrocatalysts is essential for various applications, but it poses significant challenges. A novel electrocatalyst, denoted as Ru/N, S-MoO2/CNTs, was successfully synthesized using a combination of mechano-grinding and hydrothermal/calcination techniques. The Ru/N, S-MoO2/CNTs demonstrates ultrasmall overpotentials of 12 and 163 mV in NF, 51 and 167 mV in GCE, and 54 and 173 mV in CC for HER and OER, respectively, at a current density of 10 mA/cm2 in alkaline medium. To accomplish electrocatalytic OWS, a current density of 10 mA/cm2 can be obtained by using a cell voltage of 1.446 V. Theoretical studies demonstrated that the inclusion of Ru, N, and S triggers a change in the composition of MoO2; produces oxygen vacancies; and forms Ru, N, and S-oxygen-Mo catalytic centers. The combination of Ru, N, and S nanoclusters; Ru, N, and S-oxygen-Mo catalytic centers; and OVs-enriched MoO2 would position it among the top electrocatalysts.

Infectious and Inflammatory Microenvironment Self-Adaptive Artificial Peroxisomes with Synergetic Co-Ru Pair Centers for Programmed Diabetic Ulcer Therapy

Complex microenvironments with bacterial infection, persistent inflammation, and impaired angiogenesis are the major challenges in chronic refractory diabetic ulcers. To address this challenge, a comprehensive strategy with highly effective and integrated antimicrobial, anti-inflammatory, and accelerated angiogenesis will offer a new pathway to the rapid healing of infected diabetic ulcers. Here, inspired by the tunable reactive oxygen species (ROS) regulation properties of natural peroxisomes, this work reports the design of infectious and inflammatory microenvironments self-adaptive artificial peroxisomes with synergetic Co-Ru pair centers (APCR) for programmed diabetic ulcer therapy. Benefiting from the synergistic Co and Ru atoms, the APCR can simultaneously achieve ROS production and metabolic inhibition for bacterial sterilization in the infectious microenvironment. After disinfection, the APCR can also eliminate ROS to alleviate oxidative stress in the inflammatory microenvironment and promote wound regeneration. The data demonstrate that the APCR combines highly effective antibacterial, anti-inflammatory, and provascular regeneration capabilities, making it an efficient and safe nanomedicine for treating infectious and inflammatory diabetic foot ulcers via a programmed microenvironment self-adaptive treatment pathway. This work expects that synthesizing artificial peroxisomes with microenvironments self-adaptive and bifunctional enzyme-like ROS regulation properties will provide a promising path to construct ROS catalytic materials for treating complex diabetic ulcers, trauma, or other infection-caused diseases.

Amorphous/polycrystalline NiMn selenide for high-performance supercapacitors

Transition-metal selenides have been extensively studied as promising electrode materials for supercapacitors. Engineering amorphous/crystalline heterostructures is an effective strategy to improve rich active sites for accelerating redox reaction kinetics but still lacks exploration. In this study, an amorphous/crystalline heterostructure was designed and constructed by selenizing the self-sacrificial template NiMnS to generate amorphous Mn/polycrystalline Ni0.85Se-NiSe2 heterophase via the phase transformation from metal sulfide into metal selenide. The synergy of the complementary multi-components and amorphous/polycrystalline heterophase could enrich electron/ion-transport channels and expose abundant active sites, which accelerated electron/ion transfer and Faradaic reaction kinetics during charging/discharging. As expected, the optimal NiMnSe exhibited a high specific charge (1389.1 C g-1 at 1 A g-1), a good rate capability, and an excellent lifespan (88.9% retention). Moreover, the fabricated NiMnSe//activated carbon device achieved a long cycle life and energy density of 48.0 W h kg-1 at 800 W kg-1, shedding light on the potential for use in practical applications, such as electrochemical energy-storage devices.

Low-Frequency Evolution Mechanism of Customized HEAs-Based Electromagnetic Response Modes Manipulated by Carbothermal Shock

An emerging carbothermal shock method is an ultra-convenient strategy for synthesizing high-entropy alloys (HEAs), in which the intelligent combination of carbon support and HEAs can be serve as a decisive factor for interpreting the trade-off relationship between conductive gene and dielectric gene. However, the feedback mechanism of HEAs ordering degree on electromagnetic (EM) response in 2-18 GHz has not been comprehensively demystified. Herein, while lignin-based carbon fiber paper (L-CFP) as carbon support, L-CFP/FeCoNiCuZn-X with is prepared by carbothermal shock method. The reflection loss of -82.6 dB with thickness of 1.31 mm is achieved by means of pointing electron enrichment within L-CFP/FeCoNiCuZn HEAs heterointerfaces verified by theoretical calculations. Simultaneously, low-frequency evolution with high-intensity and broadband EM response relies on a "sacrificing" strategy achieved by construction of polymorphic L-CFP/semi-disordered-HEAs heterointerfaces. The practicality of L-CFP/FeCoNiCuZn-X in complex environments is given prominence to thermal conductivity, hydrophobicity, and electrocatalytic property. This work is of great significance for insightful mechanism analysis of HEAs in the application of electromagnetic wave absorption.

A Coordination-Derived Cerium-Based Amorphous-Crystalline Heterostructure with High Electrocatalytic Oxygen Evolution Activity

The rational design of heterogeneous catalysts is crucial for achieving optimal physicochemical properties and high electrochemical activity. However, the development of new amorphous-crystalline heterostructures is significantly more challenging than that of the existing crystalline-crystalline heterostructures. To overcome these issues, a coordination-assisted strategy that can help fabricate an amorphous NiO/crystalline NiCeOx (a-NiO/c-NiCeOx) heterostructure is reported herein. The coordination geometry of the organic ligands plays a pivotal role in permitting the formation of coordination polymers with high Ni contents. This consequently provides an opportunity for enabling the supersaturation of Ni in the NiCeOx structure during annealing, leading to the endogenous spillover of Ni from the depths of NiCeOx to its surface. The resulting heterostructure, featuring strongly coupled amorphous NiO and crystalline NiCeOx, exhibits harmonious interactions in addition to low overpotentials and high catalytic stability in the oxygen evolution reaction (OER). Theoretical calculations prove that the amorphous-crystalline interfaces facilitate charge transfer, which plays a critical role in regulating the local electron density of the Ni sites, thereby promoting the adsorption of oxygen-based intermediates on the Ni sites and lowering the dissociation-related energy barriers. Overall, this study underscores the potential of coordinating different metal ions at the molecular level to advance amorphous-crystalline heterostructure design.

Interfacial Electronic Interaction in Amorphous-Crystalline CeOx-Sn Heterostructures for Optimizing CO2 to Formate Conversion

Formate, a crucial chemical raw material, holds significant promise for industrial applications in the context of CO2 electroreduction reaction (CO2RR). Despite its potential, challenges, such as poor selectivity and low formation rate at high current densities persist, primarily due to the competing hydrogen evolution reaction (HER) and high energy barriers associated with *OCHO intermediate generation. Herein, one-step chemical co-reduction strategy is employed to construct an amorphous-crystalline CeOx-Sn heterostructure, demonstrating remarkable catalytic performance in converting CO2 to formate. The optimized CeOx-Sn heterostructures reach a current density of 265.1 mA cm-2 and a formate Faraday efficiency of 95% at -1.07 V versus RHE. Especially, CeOx-Sn achieves a formate current density of 444.4 mA cm-2 and a formate production rate of 9211.8 µmol h-1 cm-2 at -1.67 V versus RHE, surpassing most previously reported materials. Experimental results, coupled with （density functional theory）DFT calculations confirm that robust interface interaction between CeOx and Sn active center induces electron transfer from crystalline Sn site to amorphous CeOx, some Ce4+of CeOx get electrons and convert to unsaturated Ce3+, optimizing the electronic structure of active Sn. This amorphous-crystalline heterostructure promotes electron transfer during CO2RR, reducing the energy barrier formed by *OCHO intermediates, and thus achieving efficient reduction of CO2 to formate.

Rapid Synthesis of Nickel Hydroxide/Pt-Based Alloy Heterointerface for Hydrogen Evolution in Full pH Range

The huge application potential of nanoelectrocatalysts can become available only under the condition of scalable and reproducible preparation of nanomaterials (NMs). It is easily overlooked that most of the preparation methods for efficient platinum (Pt)-based electrocatalysts are complicated in process and time-/energy-consuming, which is not conducive to scalable and sustainable production. Herein, we propose a rapid and facile method to in situ construct a heterointerface between nickel hydroxide (Ni(OH)2) and NiPt alloy, in which the preparation steps are easy-to-operate and can be finished in 1 h. Furthermore, the ensemble effect between the Ni(OH)2 substrate and NiPt active sites benefits the water dissociation process in nonacidic conditions, while the electronic effect in NiPt contributes to the downshifted d-band center of Pt and the proper Gibbs free energy of hydrogen species. As a result, the well-designed and quickly constructed Ni(OH)2-Ni3Pt heterointerfaces reveal lower overpotentials for HER compared with most reported Pt-based and commercial Pt/C catalysts in nonacidic conditions. This study is expected to provide useful reference information for the development of facile and robust methods for the preparation of more efficient Pt-based electrocatalysts.

Recent progress in energy-saving electrocatalytic hydrogen production via regulating the anodic oxidation reaction

Hydrogen energy with its advantages of high calorific value, renewable nature, and zero carbon emissions is considered an ideal candidate for clean energy in the future. The electrochemical decomposition of water, powered by renewable and clean energy sources, presents a sustainable and environmentally friendly approach to hydrogen production. However, the traditional electrochemical overall water-splitting reaction (OWSR) is limited by the anodic oxygen evolution reaction (OER) with sluggish kinetics. Although important advances have been made in efficient OER catalysts, the theoretical thermodynamic difficulty predetermines the inevitable large potential (1.23 V vs. RHE for the OER) and high energy consumption for the conventional water electrolysis to obtain H2. Besides, the generation of reactive oxygen species at high oxidation potentials can lead to equipment degradation and increase maintenance costs. Therefore, to address these challenges, thermodynamically favorable anodic oxidation reactions with lower oxidation potentials than the OER are used to couple with the cathodic hydrogen evolution reaction (HER) to construct new coupling hydrogen production systems. Meanwhile, a series of robust catalysts applied in these new coupled systems are exploited to improve the energy conversion efficiency of hydrogen production. Besides, the electrochemical neutralization energy (ENE) of the asymmetric electrolytes with a pH gradient can further promote the decrease in application voltage and energy consumption for hydrogen production. In this review, we aim to provide an overview of the advancements in electrochemical hydrogen production strategies with low energy consumption, including (1) the traditional electrochemical overall water splitting reaction (OWSR, HER-OER); (2) the small molecule sacrificial agent oxidation reaction (SAOR) and (3) the electrochemical oxidation synthesis reaction (EOSR) coupling with the HER (HER-SAOR, HER-EOSR), respectively; (4) regulating the pH gradient of the cathodic and anodic electrolytes. The operating principle, advantages, and the latest progress of these hydrogen production systems are analyzed in detail. In particular, the recent progress in the catalytic materials applied to these coupled systems and the corresponding catalytic mechanism are further discussed. Furthermore, we also provide a perspective on the potential challenges and future directions to foster advancements in electrocatalytic green sustainable hydrogen production.

CoPS/Co4S3 Heterojunction with Highly Exposed Active Sites and Dual-site Synergy for Effective Hydrogen Evolution Reactions

Cobalt phosphosulphide (CoPS) has recently been recognized as a potentially effective electrocatalyst for the hydrogen evolution reaction (HER). However, there have been no research on the design of CoPS-based heterojunctions to boost their HER performance. Herein, CoPS/Co4S3 heterojunction was prepared by phosphating treatment based on defect-rich flower-like Co1-xS precursors. The high specific surface area of nanopetals, together with the heterojunction structure with inhomogeneous strain, exposes more active sites in the catalyst. The electronic structure of the catalyst is reconfigured as a result of the interfacial interactions, which promote the catalyst's ability to adsorb hydrogen and conduct electricity. The synergistic effect of the Co and S dual-site further enhance the catalytic activity. The catalyst has overpotentials of 61 and 70 mV to attain a current density of 10 mA cm-2 in acidic and alkaline media, respectively, which renders it competitive with previously reported analogous catalysts. This work proposes an effective technique for constructing transition metal phosphosulfide heterojunctions, as well as the development of an efficient HER electrocatalyst.

Advancing electrocatalytic reactions through mapping key intermediates to active sites via descriptors

Descriptors play a crucial role in electrocatalysis as they can provide valuable insights into the electrochemical performance of energy conversion and storage processes. They allow for the understanding of different catalytic activities and enable the prediction of better catalysts without relying on the time-consuming trial-and-error approaches. Hence, this comprehensive review focuses on highlighting the significant advancements in commonly used descriptors for critical electrocatalytic reactions. First, the fundamental reaction processes and key intermediates involved in several electrocatalytic reactions are summarized. Subsequently, three types of descriptors are classified and introduced based on different reactions and catalysts. These include d-band center descriptors, readily accessible intrinsic property descriptors, and spin-related descriptors, all of which contribute to a profound understanding of catalytic behavior. Furthermore, multi-type descriptors that collectively determine the catalytic performance are also summarized. Finally, we discuss the future of descriptors, envisioning their potential to integrate multiple factors, broaden application scopes, and synergize with artificial intelligence for more efficient catalyst design and discovery.

Crystalline-Amorphous Interfaces Engineering of CoO-InOx for Highly Efficient CO2 Electroreduction to CO

As a fundamental product of CO2 conversion through two-electron transfer, CO is used to produce numerous chemicals and fuels with high efficiency, which has broad application prospects. In this work, it has successfully optimized catalytic activity by fabricating an electrocatalyst featuring crystalline-amorphous CoO-InOx interfaces, thereby significantly expediting CO production. The 1.21%CoO-InOx consists of randomly dispersed CoO crystalline particles among amorphous InOx nanoribbons. In contrast to the same-phase structure, the unique CoO-InOx heterostructure provides plentiful reactive crystalline-amorphous interfacial sites. The Faradaic efficiency of CO (FECO) can reach up to 95.67% with a current density of 61.72 mA cm-2 in a typical H-cell using MeCN containing 0.5 M 1-Butyl-3-methylimidazolium hexafluorophosphate ([Bmim]PF6) as the electrolyte. Comprehensive experiments indicate that CoO-InOx interfaces with optimization of charge transfer enhance the double-layer capacitance and CO2 adsorption capacity. Theoretical calculations further reveal that the regulating of the electronic structure at interfacial sites not only optimizes the Gibbs free energy of *COOH intermediate formation but also inhibits HER, resulting in high selectivity toward CO.

Construction of Co-Se-W at Interfaces of Phase-Mixed Cobalt Selenide via Spontaneous Phase Transition for Platinum-Like Hydrogen Evolution Activity and Long-Term Durability in Alkaline and Acidic Media

Cost-effective transition metal chalcogenides are highly promising electrocatalysts for both alkaline and acidic hydrogen evolution reactions (HER). However, unsatisfactory HER kinetics and stability have severely hindered their applications in industrial water electrolysis. Herein, a nanoflowers-shaped W-doped cubic/orthorhombic phase-mixed CoSe2 catalyst ((c/o)-CoSe2-W) is reported. The W doping induces spontaneous phase transition from stable phase cubic CoSe2 (c-CoSe2) to metastable phase orthorhombic CoSe2, which not only enables precise regulation of the ratio of two phases but also realizes W doping at the interfaces of two phases. The (c/o)-CoSe2-W catalyst exhibits a Pt-like HER activity in both alkaline and acidic media, with record-low HER overpotentials of 29.8 mV (alkaline) and 35.9 mV (acidic) at 10 mA cm-2, respectively, surpassing the vast majority of previously reported non-precious metal electrocatalysts for both alkaline and acidic HER. The Pt-like HER activities originate from the formation of Co-Se-W active species on the c-CoSe2 side at the phase interface, which effectively modulates electron structures of active sites, not only enhancing H2O adsorption and dissociation at Co sites but also optimizing H* adsorption to ΔGH* ≈ 0 at W sites. Benefiting from the abundant phase interfaces, the catalyst also displays outstanding long-term durability in both acidic and alkaline media.