Multicomponent Intermetallic Nanoparticles on Hierarchical Metal Network as Versatile Electrocatalysts for Highly Efficient Water Splitting

Developing high-efficiency and cost-effective alloy catalysts toward hydrogen-evolution reaction (HER) is crucial for large-scale hydrogen production via electrochemical water splitting, but conventional single-principal-element alloy design usually causes insufficient activity and durability of state-of-the-art multimetallic catalysts based on non-precious transition metals. Herein, we report multicomponent intermetallic Mo(NiFeCo)₄ nanoparticles seamlessly integrated on hierarchical nickel network (Mo(NiFeCo)₄/Ni) as robust hydrogen-evolution electrocatalysts with remarkably improved activity and durability by making use of iron and cobalt atoms partially substituting nickel sites to form high-entropy NiFeCo sublattice in intermetallic MoNi₄ matrix, which serve as bifunctional electroactive sites for both water dissociation and adsorption/combination of hydrogen intermediate and improves thermodynamic stability. By virtue of bicontinuous nanoporous nickel skeleton facilitating electron/ion transportation, self-supported nanoporous Mo(NiFeCo)₄/Ni electrode exhibits exceptional HER electrocatalysis, with low Tafel slope (≈35 mV dec⁻¹), high current density (≈2300 mA cm⁻²) at low overpotential (200 mV) and long-term durability in 1 m KOH. When coupled to its electrooxidized and nitrified derivative for oxygen-evolution reaction, their alkaline water electrolyzers operate with a superior overall water-splitting output, outperforming the one constructed with commercially available noble-metal-based catalysts. These electrochemical properties make it an attractive candidate as electrocatalyst in alkaline water electrolysis for large-scale hydrogen generation.     

NiMo Solid Solution Nanowire Array Electrodes for Highly Efficient Hydrogen Evolution Reaction

Developing high‐performance noble metal–free electrodes for efficient water electrolysis for hydrogen production is of paramount importance for future renewable energy resources. However, a grand challenge is to tailor the factors affecting the catalytic electrodes such as morphology, structure, and composition of nonprecious metals. Alloying catalytic metals can lead to a synergistic effect for superior electrocatalytic properties. However, alloy formation in solution at low synthesis temperatures may result in better catalytic properties as compared to those at high temperatures due to the controlled reaction kinetics of nucleation and growth mechanisms. Herein, an aqueous solution–based preparation technology is developed to produce NiMo alloy nanowire arrays. The NiMo alloy shows significantly improved hydrogen evolution reaction (HER) catalytic activity, featured with extremely low overpotentials of 17 and 98 mV at 10 and 400 mA cm^?2, respectively, in an alkaline medium, which are better than most state‐of‐the‐art non‐noble metal–based catalysts and even comparable to platinum‐based electrodes. Analyses indicate that the lattice distortions induced by Mo incorporation, increased interfacial activity by alloy formation, and plenty of MoNi₄ active sites at nanowires surface collectively contribute to remarkably enhanced catalytic activity. This study provides a powerful toolbox for highly efficient nonprecious metal–based electrodes for practical HER application.     

A Self-Supported High-Entropy Metallic Glass with a Nanosponge Architecture for Efficient Hydrogen Evolution under Alkaline and Acidic Conditions

Developing highly efficient and durable electrocatalysts for hydrogen evolution reaction (HER) under both alkaline and acidic media is crucial for the future development of a hydrogen economy. However, state-of-the-art high-performance electrocatalysts recently developed are based on carbon carriers mediated by binding noble elements and their complicated processing methods are a major impediment to commercialization. Here, inspired by the high-entropy alloy concept with its inherent multinary nature and using a glassy alloy design with its chemical homogeneity and tunability, we present a scalable strategy to alloy five equiatomic elements, PdPtCuNiP, into a high-entropy metallic glass (HEMG) for HER in both alkaline and acidic conditions. Surface dealloying of the HEMG creates a nanosponge-like architecture with nanopores and embedded nanocrystals that provides abundant active sites to achieve outstanding HER activity. The obtained overpotentials at a current density of 10 mA cm⁻² are 32 and 62 mV in 1.0 m KOH and 0.5 m H₂SO₄ solutions, respectively, outperforming most currently available electrocatalysts. Density functional theory reveals that a lattice distortion and the chemical complexity of the nanocrystals lead to a strong synergistic effect on the electronic structure that further stabilizes hydrogen proton adsorption/desorption. This HEMG strategy establishes a new paradigm for designing compositionally complex alloys for electrochemical reactions.     

Layer-by-Layer Assembly-Based Electrocatalytic Fibril Electrodes Enabling Extremely Low Overpotentials and Stable Operation at 1 A cm−2 in Water-Splitting Reaction

For the practical use of water electrolyzers using non-noble metal catalysts, it is crucial to minimize the overpotentials for the hydrogen and oxygen evolution reactions. Here, cotton-based, highly porous electrocatalytic electrodes are introduced with extremely low overpotentials and fast reaction kinetics using metal nanoparticle assembly-driven electroplating. Hydrophobic metal nanoparticles are layer-by-layer assembled with small-molecule linkers onto cotton fibrils to form the conductive seeds for effective electroplating of non-noble metal electrocatalysts. This approach converts insulating cottons to highly electrocatalytic textiles while maintaining their intrinsic 3D porous structure with extremely large surface area without metal agglomerations. To prepare hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) electrodes, Ni is first electroplated onto the conductive cotton textile (HER electrode), and NiFe is subsequently electroplated onto the Ni–electroplated textile (OER electrode). The resulting HER and OER electrodes exhibit remarkably low overpotentials of 12 mV at 10 mA cm⁻² and 214 mV at 50 mA cm⁻², respectively. The two-electrode water electrolyzer exhibits a current density of 10 mA cm⁻² at a low cell voltage of 1.39 V. Additionally, the operational stability of the device is well maintained even at an extremely high current density of 1 A cm⁻² for at least 100 h.     

Facile Fabrication of Robust Hydrogen Evolution Electrodes under High Current Densities via Pt@Cu Interactions

Durable and efficient hydrogen evolution reaction (HER) electrocatalysts that can satisfy industrial requirements need to be developed. Platinum (Pt)-based catalysts represent the benchmark performance but are less studied for HER under high current densities in neutral electrolytes due to their high cost, poor stability, and extra water dissociation step. Here a facile and low-temperature synthesis for constructing “blackberry-shaped” Pt nanocrystals on copper (Cu) foams with low loading as self-standing electrodes for HER in neutral media is proposed. Optimized hydrogen adsorption free energy and robust interaction induced by charge density exchange between Pt and Cu ensure the efficient and robust HER, especially under high current densities, which are demonstrated from both experimental and theoretical approaches. The electrode exhibits small overpotentials of 35 and 438 mV to reach current densities of -10 and -1000 mA cm⁻², respectively. Meanwhile the electrode illustrates outstanding stability during chronoamperometry measurement under high current densities (-100 to -400 mA cm⁻²) and 1000 cycles linear sweep voltammetry tests reaching -1000 mA cm⁻². This study provides new design strategies for self-standing electrocatalysts by fabricating robust metal–metal interactions between active materials and current collectors, thus facilitating the stable function of electrodes for HER under technologically relevant high current densities.     

Density-Controlled Metal Nanocluster with Modulated Surface for pH-Universal and Robust Water Splitting

Reducing the particle sizes of transition metals (TMs) and avoiding their aggregation are crucial for increasing the TMs atom utilization and enhancing their industrial potential. However, it is still challenging to achieve uniform distributed and density-controlled TMs nanoclusters (NCs) under high temperatures due to the strong interatomic metallic bonds and high surface energy of NCs. Herein, a series of TMs NCs with controllable density and nitrogen-modulated surface are prepared with the assistance of a selected covalent organic polymer (COP), which can provide continuous anchoring sites and size-limited skeletons. The prepared Ir NCs show superior hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) activities than commercial Pt/C and Ir/C in both acid and alkaline media. In particular, the as-prepared Ir NCs exhibit remarkable full water splitting performance, reaching a current density of 10 mA cm⁻² at ultralow overpotentials of 1.42 and 1.43 V in alkaline and acidic electrolyte, respectively. The excellent electrocatalytic activities are attributed to the increased surface atom utilization and the improved intrinsic activity of Ir NCs. More importantly, the Ir NCs catalyst shows superior long-term stability due to the strong interaction between Ir NCs and the N-doped carbon layer.     

Complementary Functions of Vanadium in Boosting Electrocatalytic Activity of CuCoNiFeMn High-Entropy Alloy for Water Splitting

High entropy alloys (HEAs) composed of multi-metal elements in a single crystal structure are attractive for electrocatalysis. However, identifying the complementary functions of each element in HEAs is a prerequisite. Thus, V_xCuCoNiFeMn (x = 0, 0.5, and 1.0) HEAs are investigated to identify the active role of vanadium in improving the electrocatalytic activity for the hydrogen evolution reaction (HER). Structural studies show the successful incorporation of V in the HEA. V_1.0CuCoNiFeMn (V_1.0-HEA) shows an overpotential of 250 mV versus the reversible hydrogen electrode (at −50 mA cm⁻², 1 m KOH), which is ≈170 mV lower than that of control-HEA (422 mV). Improves electrical conductivity and the electrochemical surface area of the V_1.0-HEA accelerated HER activity. Furthermore, density functional theory calculations reveal reduced water dissociation and hydrogen adsorption energies of V_1.0-HEA, resulting in the boosted HER kinetics. The effect of V incorporation on the barrier height and active sites at the surface of V_1.0-HEA is schematically explained. This study can be facilitated for the development of highly active HEAs for large-scale electrochemical water splitting.     

A Cobalt‐Based Amorphous Bifunctional Electrocatalysts for Water‐Splitting Evolved from a Single‐Source Lazulite Cobalt Phosphate

Over the years, cobalt phosphates (amorphous or crystalline) have been projected as one of the most significant and promising classes of nonprecious catalysts and studied exclusively for the electrocatalytic and photocatalytic oxygen evolution reaction (OER). However, their successful utilization of hydrogen evolution reaction (HER) and the reaction of overall water‐splitting is rather unexplored. Herein, presented is a crystalline cobalt phosphate, Co₃(OH)₂(HPO₄)₂, structurally related to the mineral lazulite, as an efficient precatalyst for OER, HER, and water electrolysis in alkaline media. During both electrochemical OER and HER, the Co₃(OH)₂(HPO₄)₂ nanostructure was completely transformed in situ into porous amorphous CoO_x (OH) films that mediate efficient OER and HER with extremely low overpotentials of only 182 and 87 mV, respectively, at a current density of 10 mA cm^?2. When assemble as anode and cathode in a two‐electrode alkaline electrolyzer, unceasing durability over 10 days is achieved with a final cell voltage of 1.54 V, which is superior to the recently reported effective bifunctional electrocatalysts. The strategy to achieve more active sites for oxygen and hydrogen generation via in situ oxidation or reduction from a well‐defined inorganic material provides an opportunity to develop cost‐effective and efficient electrocatalysts for renewable energy technologies.     

Construction of Nickel-Based Dual Heterointerfaces towards Accelerated Alkaline Hydrogen Evolution via Boosting Multi-Step Elementary Reaction

The introduction of composite components to construct heterointerfaces is an important way to improve the electrocatalytic performance of materials. However, selecting appropriate components to accelerate the elementary reaction rates of the hydrogen evolution reaction (HER) in alkaline media is still in challenge. Here, a Ni-CeF₃-VN multi-component material is successfully constructed, which exhibits excellent HER catalytic activity (33 mV at 10 mA cm⁻²). The experimental and computational results show that the Ni-VN and Ni-CeF₃ dual heterointerfaces can effectively promote the transfer of OH⁻ adsorption site from Ni to VN and optimize the adsorption energy of intermediate H respectively, which together accelerate the rate of the multi-step hydrogen evolution reaction in alkaline solution and thus lead to a significantly improved HER performance compared to the pure Ni. Furthermore, the solar to hydrogen (STH) efficiency can reach 10.34%. This work provides an effective guide for the design of high-efficiency multicomponent materials in the future.     

Mo-/Co-N-C Hybrid Nanosheets Oriented on Hierarchical Nanoporous Cu as Versatile Electrocatalysts for Efficient Water Splitting

Designing robust and cost-effective electrocatalysts based on Earth-abundant elements is crucial for large-scale hydrogen production through electrochemical water splitting. Here, nitrogen-doped carbon engrafted Mo₂N/CoN hybrid nanosheets that are seamlessly oriented on hierarchical nanoporous Cu scaffold (Mo-/Co-N-C/Cu), as highly efficient electrocatalysts for alkaline hydrogen evolution reaction are reported. The constituent heterostructured Mo₂N/CoN nanosheets work as bifunctional electroactive sites for both water dissociation and adsorption/desorption of hydrogen intermediates while the nitrogen-doped carbon bridges electron transfers between electroactive sites and interconnective Cu current collectors by making use of Mo-/Co-N-C bonds and intimate C/Cu contacts at interfaces. As a consequence of unique architecture having electroactive sites to be sufficiently accessible, self-supported nanoporous Mo-/Co-N-C/Cu hybrid electrodes exhibit outstanding electrocatalysis in 1 m KOH, with a negligible onset overpotential and a low Tafel slope of 47 mV dec⁻¹. They only take overpotential of as low as 230 mV to reach current density of 1000 mA cm⁻². When coupled with their electro-oxidized derivatives that mediate efficiently the oxygen evolution reaction, the alkaline water electrolyzer can achieve ≈100 mA cm⁻² at 1.622 V in 1 m KOH electrolyte, ≈0.343 V lower than the device constructed with commercially available Pt/C and Ir/C nanocatalysts immobilized on nanoporous Cu electrodes.     

Nonprecious Intermetallic Al7Cu4Ni Nanocrystals Seamlessly Integrated in Freestanding Bimodal Nanoporous Copper for Efficient Hydrogen Evolution Catalysis

Tremendous demands for renewable hydrogen generated from water splitting have stimulated intensive research on developing earth‐abundant, non‐noble, and versatile metal catalysts toward the hydrogen evolution reactions (HER). Here, self‐supported Cu‐Ni‐Al hybrid electrodes that are composed of electroactive Al₇Cu₄Ni@Cu₄Ni core/shell nanocrystals seamlessly integrated in self‐supported 3D bimodal nanoporous Cu skeleton (Bi‐NP Cu/Al₇Cu₄Ni@Cu₄Ni) as robust HER electrocatalysts in alkaline electrolyte are reported. As a result of the proper architecture, in which the Bi‐NP Cu skeleton not only facilitates both electron and electrolyte transports but also provides high specific surface areas to fully use high electrocatalytic activity of Al₇Cu₄Ni@Cu₄Ni core/shell nanocrystals, the Bi‐NP Cu/Al₇Cu₄Ni@Cu₄Ni hybrid catalysts exhibit a low onset overpotential of 60 mV and a small Tafel slope of 110 mV dec^?1, enabling the catalytic current density of 10 mA cm^?2 at a low overpotential of 139 mV. The highly stable electrochemical performance makes them promising candidates as cathode catalysts in alkaline‐based devices.     

Integration of Alloy Segregation and Surface Co?O Hybridization in Carbon-Encapsulated CoNiPt Alloy Catalyst for Superior Alkaline Hydrogen Evolution

Constructing an efficient alkaline hydrogen evolution reaction (HER) catalyst with low platinum (Pt) consumption is crucial for the cost reduction of energy devices, such as electrolyzers. Herein, nanoflower-like carbon-encapsulated CoNiPt alloy catalysts with composition segregation are designed by pyrolyzing morphology-controlled and Pt-proportion-tuned metal–organic frameworks (MOFs). The optimized catalyst containing 15% CoNiPt NFs (15%: Pt mass percentage, NFs: nanoflowers) exhibits outstanding alkaline HER performance with a low overpotential of 25 mV at a current density of 10 mA cm⁻², far outperforming those of commercial Pt/C (47 mV) and the most advanced catalysts. Such superior activity originates from an integration of segregation alloy and Co-O hybridization. The nanoflower-like hierarchical structure guarantees the full exposure of segregation alloy sites. Density functional theory calculations suggest that the segregation alloy components not only promote water dissociation but also facilitate the hydrogen adsorption process, synergistically accelerating the kinetics of alkaline HER. In addition, the activity of alkaline HER is volcanically distributed with the surface oxygen content, mainly in the form of Co_3d O_2p hybridization, which is another reason for enhanced activity. This work provides feasible insights into the design of cost-effective alkaline HER catalysts by coordinating kinetic reaction sites at segregation alloy and adjusting the appropriate oxygen content.     

Few Layered N,P Dual‐Doped Carbon‐Encapsulated Ultrafine MoP Nanocrystal/MoP Cluster Hybrids on Carbon Cloth: An Ultrahigh Active and Durable 3D Self‐Supported Integrated Electrode for Hydrogen Evolution Reaction in a Wide pH Range

Development of highly active and stable electrocatalysts is a key to realize efficient hydrogen evolution through water electrolysis. Here, the development of a 3D self‐supported integrated electrode constituting few layered N, P dual‐doped carbon‐encapsulated ultrafine MoP nanocrystal/MoP cluster hybrids on carbon cloth (FLNPC@MoP‐NC/MoP‐C/CC) is demonstrated. Benefiting from novel structural features including fully open and accessible nanoporosity, ultrasmall size of MoP‐NCs on MoP‐Cs as well as strong synergistic effects of N, P dual‐doped carbon layers with MoP‐NCs, the FLNPC@MoP‐NC/MoP‐C/CC as a 3D self‐supported binder‐free integrated electrode exhibits extraordinary catalytic activity for the hydrogen evolution reaction (HER) with extremely low overpotentials at all pH values ( j = 10 mA cm^?2 at η = 74, 106, and 69 mV in 0.5 m H₂SO₄, 1.0 m PBS, and 1.0 m KOH electrolytes, respectively). To the best of our knowledge, the ultrahigh electrocatalytic performance represents one of the best MoP‐based HER electrocatalysts reported so far. Additionally, few layered N, P dual‐doped carbon can effectively prevent MoP‐NC/MoP‐C from corrosion, making the FLNPC@MoP‐NC/MoP‐C/CC exhibit nearly unfading stability after 50 h testing in acidic, neutral, and alkaline media, which shows great promise for electrocatalytic water splitting application.     

Efficient and Durable 3D Self‐Supported Nitrogen‐Doped Carbon‐Coupled Nickel/Cobalt Phosphide Electrodes: Stoichiometric Ratio Regulated Phase‐ and Morphology‐Dependent Overall Water Splitting Performance

The construction of a novel 3D self‐supported integrated Ni_xCo_2?xP@NC (0 < x < 2) nanowall array (NA) on Ni foam (NF) electrode constituting highly dispersed Ni_xCo_2?xP nanoparticles, nanorods, nanocapsules, and nanodendrites embedded in N‐doped carbon (NC) NA grown on NF is reported. Benefiting from the collective effects of special morphological and structural design and electronic structure engineering, the Ni_xCo_2?xP@NC NA/NF electrodes exhibit superior electrocatalytic performance for water splitting with an excellent stability in a wide pH range. The optimal NiCoP@NC NA/NF electrode exhibits the best hydrogen evolution reaction (HER) activity in acidic solution so far, attaining a current density of 10 mA cm^?2 at an overpotential of 34 mV. Moreover, the electrode manifests remarkable performances toward both HER and oxygen evolution reaction in alkaline medium with only small overpotentials of 37 mV at 10 mA cm^?2 and 305 mV at 50 mA cm^?2, respectively. Most importantly, when coupling with the NiCoP@NC NA/NF electrode for overall water splitting, an alkali electrolyzer delivers a current density of 20 mA cm^?2 at a very low cell voltage of ≈1.56 V. In addition, the NiCoP@NC NA/NF electrode has outstanding long‐term durability at j = 10 mA cm^?2 with a negligible degradation in current density over 22 h in both acidic and alkaline media.     

Multisite Synergism-Induced Electron Regulation of High-Entropy Alloy Metallene for Boosting Alkaline Hydrogen Evolution Reaction

Designing the high-entropy alloys (HEAs) electrocatalysts with controllable nanostructures is of great significance for the development of efficient alkaline hydrogen evolution reaction (HER) electrocatalysts. In this study, an ultrathin HEA-PdPtRhIrCu metallene with abundant lattice distortions and defects is prepared via a facile one-step hydrothermal method. The synthesized HEA-PdPtRhIrCu metallene exhibits superior HER performance in a 1 m KOH solution, where the required overpotential of HEA-PdPtRhIrCu metallene is only 15 mV to reach a current density of −10 mA cm⁻² while possessing a low Tafel slope for 37 mV dec⁻¹. Density functional theory calculations further prove that the synergistic effect of the five elements can optimize the electronic structure to enhance the HER activity of the catalysts. In particular, the strong coupling effect and the strong bonding arising from the interaction between the multi-metal components can facilitate the electron transfer of the surface and high electroactivity. Moreover, the optimized Pt electronic structure in HEA-PdPtRhIrCu metallene promotes the optimal Pt H binding at the Pt site, thus promoting HER performance.     

Fullerene Lattice-Confined Ru Nanoparticles and Single Atoms Synergistically Boost Electrocatalytic Hydrogen Evolution Reaction

The design and construction of electrocatalysts with high efficiency, low cost and large current output suitable for industrial hydrogen production is the current development trend for water electrolysis. Herein, a lattice-confined in situ reduction effect of the 3D crystalline fullerene network (CFN) is developed to trap Ru nanoparticle (NP) and single atom (SA) via a solvothermal-pyrolysis process. The optimized product (Ru_NP-Ru_SA@CFN-800) exhibits outstanding electrocatalytic performance for alkaline hydrogen evolution reactions. To deliver a current density of 10 mA cm⁻², the Ru_NP-Ru_SA@CFN-800 merely required an overpotential of 33 mV, along with a robust electrocatalytic durability for 1400 h. Even at large current densities of 500 and 1000 mA cm⁻², the overpotentials are only 154 and 251 mV, respectively. Density function theorey calculation results indicated that the electronic synergetic effect between Ru NP and SA enable to regulate the charge distribution of Ru_NP-Ru_SA@CFN-800 and reduce the Gibbs free energy of intermediate species for water dissociation process, thereby accelerating the hydrogen evolution process. Moreover, the robust CFN matrix render this strategy patulous to other transition metals, e.g., Cu, Ni, and Co. The present study provides a new clue for the construction of novel electrocatalyst in the field of energy storage and conversion.     

Single-Atom Co-Decorated MoS2 Nanosheets Assembled on Metal Nitride Nanorod Arrays as an Efficient Bifunctional Electrocatalyst for pH-Universal Water Splitting

The commercialization of electrochemical water splitting technology requires electrocatalysts that are cost-effective, highly efficient, and stable. Herein, an advanced bifunctional electrocatalyst based on single-atom Co-decorated MoS₂ nanosheets grown on 3D titanium nitride (TiN) nanorod arrays (CoSAs-MoS₂/TiN NRs) has been developed for overall water splitting in pH-universal electrolytes. When applied as a self-standing cathodic electrode, the CoSAs-MoS₂/TiN NRs requires overpotentials of 187.5, 131.9, and 203.4 mV to reach a HER current density of 10 mA cm^–2 in acidic, alkaline, and neutral conditions, respectively, which are superior to the most previously reported non-noble metal HER electrocatalysts at the same current density. The CoSAs-MoS₂/TiN NRs anodic electrode also shows low OER overpotentials of 454.9, 340.6, and 508.0 mV, respectively, at a current density of 10 mA cm^–2 in acidic, alkaline, and neutral mediums, markedly outperforming current OER catalysts reported elsewhere. More importantly, an electrolyzer delivered from the cathodic and anodic CoSAs-MoS₂/TiN NRs electrodes exhibits an extraordinary overall water splitting performance with good stability and durability in pH-universal conditions.     

Ru-Pincer Complex-Bridged Cu-Porphyrin Polymer for Robust (Photo)Electrocatalytic H2 Evolution via Single-Atom Active Sites

Organic polymers have attracted much attention in the field of energy conversion owing to their excellent tailoring ability via heterometal incorporation and/or functionalization. Herein, a novel pincer complex-bridged porphyrin polymer is synthesized using Cu-porphyrin (CuPor) and Ru-N′NN′-pincer complex (RuN₃) as monomers. The resultant CuPor-RuN₃ polymer delivers robust electrocatalytic hydrogen evolution reaction (HER) performance with outstanding durability and ultralow overpotentials of 73 and 114 mV at a current density of 10 mA cm^-2 in acidic and alkaline media, respectively. Moreover, the CuPor-RuN₃ polymer displays great potential to fabricate photoelectrochemical (PEC) cells with a BiVO₄ photoanode, where the additional photoinduced electrons from CuPor-RuN₃ endow the BiVO₄||CuPor-RuN₃ PEC cell with much better activity for overall water splitting than the BiVO₄||Pt/C one, demonstrating that CuPor-RuN₃ would be a promising (photo)electrocatalyst to replace the benchmark Pt/C. The experimental and theoretical studies reveal that the Cu/Ru heterobimetallic centers in the polymer not only enhance the inherent electron transfer from Cu sites to Ru ones that serve as single-atom catalytic sites (Ru-N₃), but also efficiently regulate the electronic property of the Ru-N₃ sites, and thus boosting (photo)electrocatalytic HER activity. The proposed strategy opens a new avenue to fabricate porphyrin-based polymers with heteromultimetallic centers as effective HER (photo)electrocatalysts.     

Superb All-pH Hydrogen Evolution Performances Powered by Ultralow Pt-Decorated Hierarchical Ni-Mo Porous Microcolumns

Achieving efficient and robust hydrogen evolution reaction (HER) electrocatalysts under all-pH conditions is significant for clean hydrogen production. Herein, an ultralow Pt-decorated hierarchical Ni-Mo porous hybrid, consisting of Ni₃Mo₃N on MoO₂ microcolumns, is developed for all-pH HER with remarkable catalytic performances, owing to the porous structure, strong metal-support interaction, along with ultralow Pt nanoparticles and multichannel nickel foam support. The superhydrophilic and aerophilic surfaces favor mass transport during the HER process. Consequently, the porous Pt/Ni-Mo-N-O microcolumns present remarkable HER activity and durability with low overpotentials of 40.6, 101.1, and 89.5 mV to obtain 100 mA cm⁻² in basic, neutral, and acid media, respectively. Moreover, the excellent performance in alkaline seawater (40.4 mV@100 mA cm⁻²) even suppresses most of over-reported catalysts. More importantly, the two-electrode cell, assembled with Pt/Ni-Mo-N-O and NiMoO₄ as cathode and anode, exhibits excellent performance towards overall-water electrolysis with an ultralow cell voltage of 1.56 V@100 mA cm⁻².     

Mechanochemical Post-Synthesis of Metal–Organic Framework-Based Pre-Electrocatalysts with Surface Fe?O?Ni/Co Bonding for Highly Efficient Oxygen Evolution

Rational surface engineering of metal–organic frameworks (MOFs) provide potential opportunities to address the sluggish kinetics of oxygen evolution reaction (OER). However, the development of MOF-based materials with low overpotentials remains a great challenge. Herein, a post-synthesis strategy to prepare highly efficient MOF-based pre-electrocatalysts via all-solid-phase mechanochemistry is demonstrated. The surface of a Fe-based MOF (MIL-53) can be reconstructed and anchored with atomically dispersed Ni/Co sites. As expected, the optimized M-NiA-CoN exhibits a very low overpotential of 180 mV at 10 mA cm⁻² and a small Tafel slope of 41 mV dec⁻¹ in 1 m KOH electrolyte. The superior electrocatalytic OER activity is mainly due to the formation of surface Fe O Ni/Co bonding. Furthermore, density functional theory calculations reveal that the transformation from ^*OH to ^*O is the rate-determining step and the electrocatalytic OER activity trend at different metal sites is Co > Ni≈Fe.