Atomic-Level Surface Engineering of Nickel Phosphide Nanoarrays for Efficient Electrocatalytic Water Splitting at Large Current Density

Designing high-performance and cost-effective electrocatalysts for water splitting at high current density is pivotal for practical industrial applications. Herein, it is found that atomic-level surface engineering of self-supported nickel phosphide (NiP) nanoarrays via a facile cation-exchange method can substantially regulate the chemical and physical properties of catalysts by introducing Co atoms. Such surface-engineered Ni_xCo_1–xP endows several aspects of merits: i) rough nanosheet array electrode structure accessible to diffusion of electrolytes and release of gas bubbles, ii) enriched P vacancies companied by Co doping and thus increased active sites, and iii) the synergy of Ni₅P₄ and NiP₂ beneficial to catalytic activity enhancement. By virtue of finely controlling the Co contents, the optimal Ni_0.96Co_0.04P electrode achieves remarkable bifunctional electrocatalytic performance for overall water splitting at a large current density of 1000 mA cm⁻², showing overpotentials of 249.7 mV for hydrogen evolution reaction and 281.7 mV for oxygen evolution reaction. Furthermore, the Ni_0.96Co_0.04P electrode at 500 mA cm⁻² exhibits an ultralow potential (1.71 V) and ultralong durability (500 h) for overall water splitting. This study implies that the atomic-level surface engineering of the electrode materials offers a viable route for gaining high-performance catalysts for water splitting at large current density.     

Dual-Phasic Carbon with Co Single Atoms and Nanoparticles as a Bifunctional Oxygen Electrocatalyst for Rechargeable Zn–Air Batteries

The great interest in rechargeable Zn–air batteries (ZABs) arouses extensive research on low-cost, high-active, and durable bifunctional electrocatalysts to boost the sluggish oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). It remains a great challenge to simultaneously host high-active and independent ORR and OER sites in a single catalyst. Herein a dual-phasic carbon nanoarchitecture consisting of a single-atom phase for the ORR and nanosized phase for the OER is proposed. Specifically, single Co atoms supported on carbon nanotubes (single-atom phase) and nanosized Co encapsulated in zeolitic-imidazole-framework-derived carbon polyhedron (nanosized phase) are integrated together via carbon nanotube bridges. The obtained dual-phasic carbon catalyst shows a small overpotential difference of 0.74 V between OER potential at 10 mA cm⁻² and ORR half-wave potential. The ZAB based on the bifunctional catalyst demonstrates a large power density of 172 mW cm⁻². Furthermore, it shows a small charge-discharge potential gap of 0.51 V at 5 mA cm⁻² and outstanding discharge-charge cycling durability. This study provides a feasible design concept to achieve multifunctional catalysts and promotes the development of rechargeable ZABs.     

Coupling Methanol Oxidation with Hydrogen Evolution on Bifunctional Co-Doped Rh Electrocatalyst for Efficient Hydrogen Generation

Efficient hydrogen production from electrochemical overall water splitting requires high-performance electrocatalysts for hydrogen evolution reaction (HER) and a fast oxidation reaction to replace sluggish oxygen evolution reaction. Herein, Co-doped Rh nanoparticles are thus grown on carbon black using Co nanosheets as the bridge. These nanoparticles with a size of ≈1.94 nm exhibit the overpotential of as low as 2 mV at 10 mA cm⁻² for the HER, and a mass activity of as high as 889 mA mg⁻¹ for the methanol oxidation reaction (MOR) in alkaline media. As confirmed by density functional theory simulations, such excellent activity originates from Co-doping, which reduces reaction energy barriers for both the rate-determining step of a Volmer process during the HER and the conversion of *CO to COOH* during the MOR (namely the enhanced adsorption of H₂O and COOH*). Coupling boosted HER on the cathode with accelerated MOR on the anode, efficient H₂ generation is achieved. This two-electrode cell only requires a cell voltage of 1.545 V at 10 mA cm⁻² with impressive long-life cycling stability. Such performance even outperforms that of commercial Pt/C || IrO₂ cell. This study offers a new strategy to achieve efficient HER from overall water splitting.     

Assembling Amorphous Metal–Organic Frameworks onto Heteroatom-Doped Carbon Spheres for Remarkable Bifunctional Oxygen Electrocatalysis

Multifunctional electrocatalysts play an increasingly crucial role in various practical electrochemical energy conversion devices. Especially, on the air cathode of rechargeable zinc–air batteries (ZABs), oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), requiring efficient bifunctional electrocatalysts, are switched during discharging and charging process. Here, supported by the theoretical computations, a facile strategy for the in situ assembly of NiFe-MOFs nanosheets on heteroatoms-doped porous activated carbon spheres is developed. The newly designed electrocatalyst (NP-ACSs@NiFe-MOFs) shows excellent performance toward bifunctional oxygen electrocatalysis. Specifically, a remarkable low value of potential gap (ΔE = 0.61 V), which is the difference between the potential to reach an OER current density of 10 mA cm⁻² and ORR half-wave potential, is achieved in 0.1 m KOH. Notably, the aqueous ZAB based on NP-ACSs@NiFe-MOFs shows super cycle stability with small voltage gap of only 0.79 V when cycled for 450 h at 10 mA cm⁻². Also, the quasi-solid-state ZAB indicates excellent flexibility and cycling stability. This study presents a facile strategy for the rational integration of different catalytically active components, and can be extended to prepare other strongly competitive multifunctional electrocatalysts.     

Engineering Active Iron Sites on Nanoporous Bimetal Phosphide/Nitride Heterostructure Array Enabling Robust Overall Water Splitting

Alkaline water electrolysis is a commercially viable technology for green H₂ production using renewable electricity from intermittent solar or wind energy, but very few non-noble bifunctional catalysts simultaneously exhibit superb catalytic efficiency and stability at large current densities for hydrogen and oxygen evolution reactions (HER and OER, respectively), especially for iron-based catalysts. Given that iron is the most abundant and least expensive transition metal, iron-based compounds are very attractive low-cost targets as active electrocatalysts for bifunctional water splitting with large-current durability. Herein, the in situ construction of a self-supported Fe₂P/Co₂N porous heterostructure arrays possessing superb bifunctional catalytic activity in base is reported, featured by low overpotentials of 131 and 283 mV to attain a current density of 500 mA cm⁻² for HER and OER, respectively, outperforming most of non-noble bifunctional electrocatalysts reported hitherto. Particularly, this hybrid catalyst also displays an excellent overall water splitting activity, requiring low voltages of 1.561 and 1.663 V to attain 100 and 500 mA cm⁻² with excellent durability in 1 m KOH, respectively. Most importantly, the catalyst is stable for >120 h, even when the current density is 500 mA cm⁻², which is prominently superior to IrO₂⁽⁺⁾//Pt⁽⁻⁾ coupled noble electrodes, and is among the very best bifunctional catalysts reported thus far. Detailed theoretical calculations reveal that the interfacial interaction between Fe₂P and Co₂N can further improve the H* binding energy at the iron sites.     

Etching‐Doping Sedimentation Equilibrium Strategy: Accelerating Kinetics on Hollow Rh‐Doped CoFe‐Layered Double Hydroxides for Water Splitting

Exploring highly active and inexpensive bifunctional electrocatalysts for water‐splitting is considered to be one of the prerequisites for developing hydrogen energy technology. Here, an efficient simultaneous etching‐doping sedimentation equilibrium (EDSE) strategy is proposed to design and prepare hollow Rh‐doped CoFe‐layered double hydroxides for overall water splitting. The elaborate electrocatalyst with optimized composition and typical hollow structure accelerates the electrochemical reactions, which can achieve a current density of 10 mA cm^?2 at an overpotential of 28 mV (600 mA cm^?2 at 188 mV) for hydrogen evolution reaction (HER) and 100 mA cm^?2 at 245 mV for oxygen evolution reaction (OER). The cell voltage for overall water splitting of the electrolyzer assembled by this electrocatalyst is only 1.46 V, a value far lower than that of commercial electrolyzer constructed by Pt/C and RuO₂ and most reported bifunctional electrocatalysts. Furthermore, the existence of Fe vacancies introduced by Rh doping and the typical hollow structure are demonstrated to optimize the entire HER and OER processes. EDSE associates doping with template‐directed hollow structures and paves a new avenue for developing bifunctional electrocatalysts for overall water splitting. It is also believed to be practical in other catalysis fields as well.     

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.     

Electrospinning Synthesis of Self-Standing Cobalt/Nanocarbon Hybrid Membrane for Long-Life Rechargeable Zinc–Air Batteries

Integrating high-efficiency oxygen electrocatalyst directly into air electrodes is vital for zinc–air batteries to achieve higher electrochemical performance. Herein, a self-standing membrane composed of hierarchical cobalt/nanocarbon nanofibers is fabricated by the electrospinning technique. This hybrid membrane can be directly employed as the bifunctional air electrode in zinc–air batteries and can achieve a high peak power density of 304 mW cm⁻² with a long service life of 1500 h at 5 mA cm⁻². Its assembled solid-state zinc–air battery also delivers a promising power density of 176 mW cm⁻² with decent flexibility. The impressive rechargeable battery performance would be attributed to the self-standing membrane architecture integrated by oxygen electrocatalysts with abundant cobalt–nitrogen–carbon active species in the hierarchical electrode. This study may provide effective electrospinning solutions in integrating efficient electrocatalyst and electrode for energy storage and conversion technologies.     

Fabrication of Polyoxometalate Anchored Zinc Cobalt Sulfide Nanowires as a Remarkable Bifunctional Electrocatalyst for Overall Water Splitting

The advancement of a naturally rich and effective bifunctional substance for hydrogen and oxygen evolution reaction is crucial to enhance hydrogen fuel production efficiency via the electrolysis process. Herein, facile and scalable hydrothermal synthesis of bifunctional electrocatalyst of polyoxometalate anchored zinc cobalt sulfide nanowire on Ni-foam (NF) for overall water splitting is reported for the first time. The electrochemical analysis of POM@ZnCoS/NF displays significantly low HER and OER overpotentials of 170/337 and 200/300 mV to attain a current density of 10/40 and 20/50 mA cm⁻², respectively, demonstrating the notable performance of POM@ZnCoS/NF toward H₂ and O₂ evolution reaction in alkaline medium. Additionally, the electrolyzer consisting of the POM@ZnCoS/NF anode and cathode shows an appealing potential of 1.56 V to deliver 10 mA cm⁻² current density for overall water splitting. The high electrocatalytic activity of the POM@ZnCoS/NF is attributed to modulation of the electronic and chemical properties, increment of the electroactive sites and electrochemically active surface area of the zinc cobalt sulfide nanowires due to the anchorage of polyoxometalate nanoparticles. These results demonstrate the advantage of the polyoxometalate incorporation strategy for the design of cost-effective and highly competent bifunctional catalysts for complete water splitting.     

Modulating Local Interfacial Bonding Environment of Heterostructures for Energy-Saving Hydrogen Production at High Current Densities

Coupling urea oxidation reaction (UOR) with hydrogen evolution reaction (HER) is an effective energy-saving technique for hydrogen generation. However, exploring efficient bifunctional electrocatalysts under high current density is still challenging. Herein, hierarchical Fe doped cobalt selenide coupled with FeCo layered double hydroxide (Fe-Co_0.85Se/FeCo LDH) array as a self-supported superior bifunctional heterojunction electrode is rationally designed for both UOR and HER. The unique heterostructure facilitates electron transfer and interface interactions through local interfacial Co-Se/O-Fe bonding environment modulation, improving reaction kinetics and intrinsic activity. As a result, the heterostructured electrocatalyst exhibits ultralow potentials of −0.274 and 1.48 V to reach 500 mA cm⁻² for catalyzing the HER and UOR, respectively. Particularly, the full urea electrolysis system driven by Fe-Co_0.85Se/FeCo LDH delivers 300 mA cm⁻² at a relatively low potential of 1.57 V, which is 150 mV lower than the conventional water electrolysis. The combination of in situ characterization and theoretical analysis reveal that the active sites with the adjustable electronic environment are induced by the interfacial bonding of the heterojunction, facilitating the water decomposition of HER and the stabilization of intermediates in UOR. This work inspires the interfacial environment modulation to optimize advanced electrocatalysts for energy-saving H₂ production.     

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.     

Hierarchical Ni/N/C Single-Site Catalyst Achieving Industrial-Level Current Density and Ultra-Wide Potential Plateau of High CO Faradic Efficiency for CO2 Electroreduction

The practical applications of CO₂ electroreduction to CO driven by renewable electricity should simultaneously meet the requests of industrial-level CO partial current density (J_CO) at least 100 mA cm⁻², wide potential window of high CO faradic efficiency (FE_CO), and low cost. Herein, a new strategy is reported to construct porous hierarchical Ni/N/C single-site catalyst with excellent catalytic activity via coating Ni-containing ZIF-8 on mesostructured basic magnesium carbonate template followed by pyrolysis. The abundant micropores facilitate the formation of numerous edge-hosted Ni-N₄ sites with high intrinsic activity, and the interconnected macro/mesopores much promote CO₂ delivery and CO release for the full expression of intrinsic activity. Consequently, the catalyst exhibits the industrial-level J_CO of 105–462 mA cm⁻² at the potential range of −0.6∼−1.3 V with ultra-wide high FE_CO plateau (>90%@−0.4∼−1.3 V), showing great promise for practical application. This study provides a general synthetic strategy to explore high-performance hierarchical M/N/C electrocatalysts.     

Heterogeneous Bimetallic Phosphide Ni2P-Fe2P as an Efficient Bifunctional Catalyst for Water/Seawater Splitting

Developing high-performance and cost-effective bifunctional electrocatalysts for large-scale water electrolysis is desirable but remains a significant challenge. Most existing nano- and micro-structured electrocatalysts require complex synthetic procedures, making scale-up highly challenging. Here, a heterogeneous Ni₂P-Fe₂P microsheet is synthesized by directly soaking Ni foam in hydrochloric acid and an iron nitrate solution, followed by phosphidation. Benefiting from high intrinsic activity, abundant active sites, and a superior transfer coefficient, this self-supported Ni₂P-Fe₂P electrocatalyst shows superb catalytic activity toward overall water splitting, requiring low voltages of 1.682 and 1.865 V to attain current densities of 100 and 500 mA cm⁻² in 1 m KOH, respectively. Such catalytic performance is superior to the benchmark IrO₂ || Pt/C pair and also places this electrocatalyst among the best bifunctional catalysts reported thus far. Furthermore, its enhanced corrosion resistance and hydrophilic surface make it suitable for seawater splitting. It is able to achieve current densities of 100 and 500 mA cm⁻² in 1 m KOH seawater at voltages of 1.811 and 2.004 V, respectively, which, together with its robust durability, demonstrates its great potential for realistic seawater electrolysis. This work presents a general and economic approach toward the fabrication of heterogeneous metallic phosphide catalysts for water/seawater electrocatalysis.     

Optimization of Interfacial OH− Accessibility by Constructing a Delayed–Release Membrane Electrode for Ampere–Level Hydrogen Production

Achieving a high current density during electrochemical overall water splitting is a promising strategy for industrial energy conversion. The mass diffusion rate of OH⁻ ions from the electrolyte to the interfacial active sites strongly influences the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) . Herein, the delayed-release of OH⁻ ions modulated by a proper organic polymer membrane on the electrode surface can optimize the OH⁻ accessibility to the active sites (as indicated by the molecular dynamics simulations) is demonstrated and that van der Waals interaction force modulates the OH⁻ residence time in the reaction system. The remarkable performance of the membrane-modified electrode  is achieved at ultra-high current densities of 1.9 A cm⁻² (with an HER overpotential of 602 mV) and 2 A cm⁻² (with an OER overpotential of 459 mV) in 1 M KOH solution. Consequently, a super-high current density of 1.3 A cm⁻² is obtained for overall water splitting (at a voltage of only 2.2 V), which is 1.9-fold higher than that of a benchmarked Pt/C-IrO₂ (684 mA cm⁻²). Therefore, the delayed-release of OH⁻ has optimized the mass conversion efficiency of the active sites, thus improving the electrochemical performance of overall water splitting.     

Active Site Implantation for Ni(OH)2 Nanowire Network Achieves Superior Hybrid Seawater Electrolysis at 1 A cm−2 with Record-Low Cell Voltage

Direct seawater electrolysis provides a grand blueprint for green hydrogen (H₂) technology, while the high energy consumption has severely hindered its industrialization. Herein, a promising active site implantation strategy is reported for Ni(OH)₂ nanowire network electrode on nickel foam substrate by Ru doping (denoted as Ru Ni(OH)₂ NW²/NF), which can act as a dual-function catalyst for hydrazine oxidation and hydrogen evolution, achieving an ultralow working potential of 114.6 mV to reach 1000 mA cm⁻² and a small overpotential of 30 mV at 10 mA cm⁻², respectively. Importantly, using the two-electrode hydrazine oxidation assisted seawater electrolysis, it can drive a large current density of 500 mA cm⁻² at 0.736 V with over 200 h stability. To demonstrate the practicability, a home-made flow electrolyzer is constructed, which can realize the industry-level rate of 1 A cm⁻² with a record-low voltage of 1.051 V. Theoretical calculations reveal that the Ru doping activates Ni(OH)₂ by upgrading d-band centers, which raises anti-bonding energy states and thus strengthens the interaction between adsorbates and catalysts. This study not only provides a novel rationale for catalyst design, but also proposes a feasible strategy for direct alkaline seawater splitting toward sustainable, yet energy-saving H₂ production.     

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.     

Rapid Synthesis of Various Electrocatalysts on Ni Foam Using a Universal and Facile Induction Heating Method for Efficient Water Splitting

Electrocatalytic water splitting for the production of hydrogen proves to be effective and available. In general, the thermal radiation synthesis usually involves a slow heating and cooling process. Here, a high-frequency induction heating (IH) is employed to rapidly prepare various self-supported electrocatalysts grown on Ni foam (NF) in liquid- and gas-phase within 1–3 min. The NF not only serves as an in situ heating medium, but also as a growth substrate. The as-synthesized Ni nanoparticles anchored on MoO₂ nanowires supported on NF (Ni-MoO₂/NF-IH) enable catalysis of hydrogen evolution reaction (HER), showing a low overpotential of −39 mV (10 mA cm⁻²) and maintaining the stability of 12 h in alkaline condition. Moreover, the NiFe layered double hydroxide (NiFe LDH/NF-IH) is also synthesized via IH and affords outstanding oxygen evolution reaction (OER) activity with an overpotential of 246 mV (10 mA cm⁻²). The Ni-MoO₂/NF-IH and NiFe LDH/NF-IH are assembled to construct a two-electrode system, where a small cell voltage of ≈1.50 V enables a current density of 10 mA cm⁻². More importantly, this IH method is also available to rapidly synthesize other freestanding electrocatalysts on NF, such as transition metal hydroxides and metal nitrides.     

Hierarchically Porous Carbonized Wood Decorated with MoNi4-Embedded MoO2 Nanosheets: An Efficient Electrocatalyst for Water Splitting

Development of low-cost electrocatalysts for water splitting is crucial to economical hydrogen production. Here, a highly efficient electrocatalyst composed of MoNi₄-embedded amorphous MoO₂ nanosheets grown on less-tortuosity hierarchically porous carbonized wood (MoNi₄/MoO₂@CW) is reported. The generation of abundant MoNi₄/MoO₂ heterointerfaces and defects-rich MoO₂ significantly promote the adsorption and activation of reactant molecules on the MoNi₄/MoO₂@CW. The obtained MoNi₄/MoO₂@CW catalyst exhibits ultralow overpotentials of 22 and 205 mV for hydrogen evolution reaction and oxygen evolution reaction at a current density of 10 mA cm⁻², respectively. The catalyst can be used for dual-function electrodes and assembling two-electrode electrolyzer illustrates 10 mA cm⁻² at 1.47 V and superior durability over 24 h for overall water electrolysis. Moreover, it also possesses a high mass activity of 142 Ag⁻¹ MoNi₄ at 200 mV, surpassing the Pt/C catalyst (132 Ag⁻¹). The outstanding performance of the MoNi₄/MoO₂@CW is attributed to the decrease in energy barrier for water dissociation, optimal adsorption/desorption of H/O-intermediates, and fast mass transport through the porous structure, as confirmed by experimental results and density functional theory-based calculations. The MoNi₄/MoO₂@CW electrocatalyst has excellent potential for practical water splitting.     

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.     

Co-Constructing Interfaces of Multiheterostructure on MXene (Ti3C2Tx)-Modified 3D Self-Supporting Electrode for Ultraefficient Electrocatalytic HER in Alkaline Media

Electrocatalysis is a potential method for sustainable hydrogen production, and the development of non-noble metal-based effective electrocatalysts for electrochemical water splitting is the core of exploiting and utilizing renewable energy. Herein, a stupendous electrocatalyst with multiheterostructure interfaces and 3D porous structure is synthesized, and the mechanisms of enhanced electrocatalytic activity combining multicharacterizations and density functional calculations are clarified. Especially, the fabricated Co₂P/N@Ti₃C₂T_x@NF (denoted as CPN@TC) exhibits an ultralow overpotential of 15 mV to arrive at a current density of 10 mA cm⁻² with the long-term durability and a small Tafel slope of 30 mV dec⁻¹ in 1 m KOH, which even compares with noble metal catalysts favorably. The outstanding HER activity is ascribed to multiheterointerfaces for adsorbing H₂O and H*, fine conductivity for the electronic transmission, and well-designed structure for rapid transport of ions and gases. It is reasonable to think that the synthetic strategy of CPN@TC can be extended to the preparation of transition-metal-based phosphides for enhanced catalytic performance.