Synthesis and electrocatalytic activity of Ni0.85Se/MoS2 for hydrogen evolution reaction

Recently, the replacement of expensive platinum-based catalytic materials with non-precious metal materials to electrolyze water for hydrogen separation has attracted much attention. In this work, Ni_0.85Se, MoS₂ and their composite Ni_0.85Se/MoS₂ with different mole ratios are prepared successfully, as electrocatalysts to catalyze the hydrogen evolution reaction (HER) in water splitting. The result shows that MoS₂/Ni_0.85Se with a molar ratio of Mo/Ni = 30 (denoted as M30) has the best catalytic performance towards HER, with the lowest overpotential of 118 mV at 10 mA cm⁻², smallest Tafel slope of 49 mV·dec⁻¹ among all the synthesized materials. Long-term electrochemical testing shows that M30 has good stability for HER over at least 30 h. These results maybe due to the large electrochemical active surface area and high conductivity. This work shows that transition metal selenides and sulfides can form effective electrocatalyst for HER.     

Ni(OH)2/ NiSe2 hybrid nanosheet arrays for enhanced alkaline hydrogen evolution reaction

Developing efficient, non-noble electrocatalysts toward hydrogen evolution reaction (HER) in alkaline electrolytes is of important significance for future energy supplement but still a challenge. Recently, pyrite-type NiSe₂ nanomaterial has been considered as an idea HER electrocatalyst due to its high conductivity, strong corrosion resistance and low cost. However, the HER performance of NiSe₂ in alkaline electrolytes is still unsatisfactory, which is possibly limited to the activate water dissociation in alkaline media. Herein, a novel hybrid electrocatalyst of Ni(OH)₂/NiSe₂ nanosheet arrays on carbon cloth (Ni(OH)₂/NiSe₂/CC) is fabricated, exhibiting excellent HER catalytic activity with a low overpotential of 82 mV to drive a current density of 10 mAcm⁻² as well as maintaining a long-term durability for 12 h in 1.0 M KOH, which is 77 mV less than that of NiSe₂/CC and superior to most recently reported non-noble HER electrocatalysts. In addition, the Tafel slope of Ni(OH)₂/NiSe₂/CC (60 mV dec ⁻¹) is also much smaller than that of NiSe₂/CC (112 mV dec ⁻¹), suggesting a promotion kinetics of HER process for Ni(OH)₂/NiSe₂/CC. Our further experimental results show that the significantly improved activity of Ni(OH)₂/NiSe₂/CC electrode should ascribe to its enlarged active surface, good conductivity and interfacial synergy between Ni(OH)₂ and NiSe₂. The synergetic strategy may provide an efficient way to promote the HER activity of other non-noble transition metal selenides in alkaline electrolyte.     

The bifunctional 3D-on-2D FeCo/Ni(OH)2 hierarchical nanocatalyst for industrial-level electrocatalytic water splitting

Developing high-performing and cost-effective bifunctional electrocatalysts under the industrial conditions is significant for revolutionizing the hydrogen economy. Herein, we developed a bifunctional 3D-on-2D FeCo/Ni(OH)₂ hierarchical nanocatalyst on Ni mesh by a facile and low-cost method that can boost both the two half-reactions of water splitting all at once. The FeCo/Ni(OH)₂/Ni mesh showed an outstanding electrocatalytic performance under the industrial conditions (3 M KOH, 90 °C) with applied voltages of 1.47 and 1.91 V to drive the electrolyzer at 10 and 500 mA/cm², respectively, much better than the Ni(OH)₂/Ni mesh, FeCo/Ni mesh, and Raney Ni/Ni mesh samples. Furthermore, it can maintain good stability for more than 192 h under the working condition of 500 mA/cm². This promotion in electrocatalytic properties can be ascribed to the synergistic effects between 3D FeCo nanoparticles and 2D Ni(OH)₂ nanosheets, including the large electrochemically active surface areas, the intense electronic interplay between the two component and the elevated interfacial contact and charge transport. Eventually, this water electrolyzer yields a 14.7% solar-to-hydrogen efficiency when integrated with Si solar cells, which exceeds analogous solar-driven systems reported so far.     

Facile strategy to fabricate Ni2P/g-C3N4 heterojunction with excellent photocatalytic hydrogen evolution activity

Transition metal phosphides are considered as the most prospective replacements for noble metal cocatalysts used for H₂ evolution during photocatalytic water splitting. In this work, Ni₂P/g-C₃N₄ composite photocatalyst was synthesized using a simple in-situ hydrothermal method by one step. Benefiting from the excellent light trapping, efficient transfer of charge carriers and strong stability of Ni₂P nanoparticles, as well as the stable interface contact between Ni₂P and g-C₃N₄, the Ni₂P/g-C₃N₄ exhibit greatly enhanced H₂ evolution performance during photocatalytic water splitting. The optimized H₂ evolution rate can reach 3344 μmol h^?1 g^?1 over 17.5 wt% Ni₂P/g-C₃N₄, which is 68.2 times greater than that of pure g-C₃N₄ and even much greater than that of 15 wt% Pt/g-C₃N₄. The apparent quantum efficiency (QE) is about 9.1% under 420 nm monochromatic. The enhancement mechanism was demonstrated in detail by transient photocurrent responses, photoluminescence spectra and electrochemical impedance spectroscopy. This work develops a facile strategy to fabricate transition metal phosphide/semiconductor heterojunction systems with potential application for photocatalytic H₂ evolution.     

Novel noble-metal free S/Ni12P5/Cd0.5Zn0.5S composite with enhanced H2 evolution activity under visible light

Constructing composite photocatalyst is an efficient way to realize the application of photocatalysis owing to the fast separation of photocarriers. In this report, we constructed a novel ternary noble-metal free S/Ni₁₂P₅/Cd_0.5Zn_0.5S (S/Ni₁₂P₅/CZS) composite which displayed much higher activity than binary Ni₁₂P₅/CZS, S/CZS and especially CZS solid solution for H₂ generation under visible light illumination (λ ≥ 420 nm). 15% S/Ni₁₂P₅/CZS showed the highest activity of H₂ production (525.5 μmol h⁻¹) among all the samples due to the optimal separating efficiency of photocarriers, and its apparent quantum efficiency is 4.37% at 420 nm. In the photocatalytic process, the photogenerated electrons of CZS solid solution quickly moved to elemental S through Ni₁₂P₅ as solid electron transfer mediator, resulting in high separation efficiency of photocarriers and outstanding activity of H₂ production over S/Ni₁₂P₅/CZS. Moreover, S/Ni₁₂P₅/CZS presented excellent stability after 10 runs recycling experiment. The significant finding of this paper provides new strategy to rationally design composite photocatalyst for efficiently splitting water to generate clean energy H₂.     

Synthesis of Co2FeAl alloys as highly efficient electrocatalysts for alkaline hydrogen evolution reaction

The development of cost-effective non-precious metal electrocatalysts is a major challenge for water splitting applications, but it is important for the realization of renewable energy systems. Alloying has proved an effective way to design metal-based electrocatalysts, and by controlling the annealing temperature, the surface morphology and crystallinity of the alloy can be tuned to control the hydrogen evolution reaction (HER) performance. In this work, with a simple coprecipitation method, we have prepared Co₂FeAl alloys at different annealing temperatures (550 °C–670 °C), which exhibit excellent crystallinity and electrocatalytic performance for HER in alkaline solution. Among all conditions, the Co₂FeAl alloys prepared at 620 °C shows the better crystallinity and the higher purity, and it could achieve a low overpotential of 149 mV at 10 mA cm^?2 in alkaline solution. The overpotential demonstrates persistent stability with only 3 mV change after over 1000 cycles. Both density functional theory (DFT) calculations and experimental results revealed that alloying optimizes the electronic structure near the Fermi surface of the system, improving the electron transport efficiency and enhancing the catalytic activity. These Co₂FeAl alloys are appealing candidates for high-performance alkaline HER electrocatalytic electrodes in water electrolysis due to their outstanding electrocatalytic properties.     

Synthesis of ultrafine ruthenium phosphide nanoparticles and nitrogen/phosphorus dual-doped carbon hybrids as advanced electrocatalysts for all-pH hydrogen evolution reaction

Pt-group metal phosphides are widely utilized as efficient electrocatalysts for hydrogen evolution reaction (HER), whereas most of the synthetic strategies are complicated, dangerous, and toxic with the use of large amount of nitrogen (N) and/or phosphorus (P) sources. Here, we report the synthesis of ruthenium phosphide nanoparticles (NPs) confined into N/P dual-doped carbon by pyrolyzing self-prepared ruthenium-organophosphine complex using 1,3,5-triaza-7-phosphadamantane (PTA) as the ligand and N/P sources. The achieved S–RuP₂/NPC displayed excellent electrocatalytic activity (overpotentials of 19, 37, and 49 mV in alkaline, neutral, and acidic media, respectively, at 10 mA cm⁻²) toward HER at all pH ranges. The high performance of S–RuP₂/NPC must be ascribed to the homogeneously distributed and P-rich RuP₂ NPs with the diameter of 3.29 nm on the NPC surface, which can considerably improve the atom utilization for HER. The present synthetic strategy not only avoids the use of additional N/P sources but also the generation of flammable and toxic PH₃ gas. This synthetic strategy can be extended to prepare other traditional metal phosphides for electrocatalytic applications.     

Efficient bifunctional hydrogen and oxygen evolution reaction electrocatalyst based on the NU-1000/CuCo2S4 heterojunction

One of the current necessities to produce clean energy is the logical design of inexpensive noble-metal free electrocatalysts with developed structure and composition for electrochemical water splitting. In this study, we introduce a new core-shell-structured bifunctional electrocatalyst of NU-1000/CuCo₂S₄ for oxygen evolution reaction (OER), hydrogen evolution reaction (HER) and overall water splitting for the first time. Own to unique structure with rich porosity, high electrical conductivity, high stability and larger density of active sites, this nanocomposite can produce water electrolysis in a 1 M KOH solution. The electrochemical measurements show overpotentials of 335 mV for OER and 93 mV for HER at a current density of 10 mAcm⁻². Also, the NU-1000/CuCo₂S₄ nanocomposite exhibits Tafel slope values of 110 mV dec⁻¹ and 103 mV dec⁻¹ for HER and OER, respectively. Besides, NU-1000/CuCo₂S₄ presents a significant long-term stability in a 72 h run. Additionally, NU-1000/CuCo₂S₄ requires 1.55 V to deliver 10 mA cm⁻² current density in overall water splitting. According to these results, we hope to use this electrocatalyst in producing oxygen and hydrogen from water.     

Growth of nickel vacancy NiFe-LDHs on Ni(OH)2 nanosheets as highly efficient bifunctional electrocatalyst for overall water splitting

A bifunctional electrocatalyst was fabricated by in-situ vertical growth of Ni(OH)₂ nanosheets on nickel foam (NF), with subsequent accretion of nickel vacancy NiFe-LDHs (Ni^vacFe-LDHs) by two step hydrothermal method. It was exhibited to be a high-efficiency overall water splitting performance with good stability. The low over-potentials of 292, 330, and 376 mV were acquired when the current density was selected as 50, 100, and 200 mA/cm² for oxygen evolution reaction (OER) with a relatively low Tafel slope. It also achieved low over-potentials of 116 and 247 mV when the current densities were 10 and 200 mA/cm² for hydrogen evolution reaction (HER), and Tafel slope was estimated to be 95.87 mV/dec. For the overall water splitting, NF–Ni(OH)₂-Ni^vacFe-LDHs needed only a low overpotential (291 mV) to achieve 25 mA/cm² in 1 mol/L potassium hydroxide. The long-term testing of this electrode for 24 h chronopotentiometric test at 25 mA/cm² demonstrated very eminent stability.     

Facile construction of heterostructural Ni3(NO3)2(OH)4/CeO2 bifunctional catalysts for boosted overall water splitting

Interface engineering has aroused vitally widespread concern since it could be an effective strategy for exploring high-performance and low-cost water oxidation electrocatalysts. Herein, we report a hetero-structured Ni₃(NO₃)₂(OH)₄/CeO₂/NF (NNO/CeO₂/NF) electrode, exhibiting superior performance owning to the NO₃^? anion substitution for the OH^? in nickel hydroxide to form Ni₃(NO₃)₂(OH)₄, together with its interface synergy with ceria. In alkaline solution, the NNO/CeO₂/NF electrocatalyst could catalyze the OER with an overpotential of 330 mV to approach 50 mA cm^?2. Also, it needs only an overpotential of 120 mV to reach 10 mA cm^?2 for HER. Additionally, when a standard two-electrode water electrolyzer is fabricated by employing NNO/CeO₂/NF as both the cathode and anode, it can generate 10 mA cm^?2 at 1.64 V and operate steadily without performance degradation after 25 h. This research provides a novel perspective for reasonable design of advanced catalytic materials with improvements in the field of electrocatalysis.     

In situ electro-oxidation modulation of Ru(OH)x/Ag supported on nickel foam for efficient hydrogen evolution reaction in alkaline media

Transition metal hydroxides for hydrogen evolution reaction (HER) usually have been limited by poor intrinsic activity and weak conductivity. In our work, in situ electro-oxidation as an effective way has been used to modulate the electronic states of active sites for ruthenium hydroxides, which provides obviously enhanced activity for HER in alkaline media. Ag-modified nickel foam (NF) as substrate can provide the excellent conductivity to improve the charge transfer rate of Ru(OH)_x/Ag/NF. In situ electro-oxidation process has been conducted for Ru(OH)_x/Ag/NF through OER measurements in alkaline media, which results in the formation of more Ru (IV) as higher actives sites for HER. Compared to Ru(OH)_x/NF, X-ray photoelectron spectroscopy (XPS) and polarization curves prove that Ag doping in Ru(OH)_x/Ag/NF may contribute to the oxidization of ruthenium from Ru (III) to Ru (IV) during in situ electro-oxidation. The obtained Ru(OH)_x/Ag/NF exhibits Pt-like HER activity with a very low overpotential of 103.2 mV to drive 100 mA cm⁻² in 1.0 M KOH. The excellent stability of Ru(OH)_x/Ag/NF has also been demonstrated. Therefore, our work provides a new strategy by modulating valence state of active sites for transition metal hydroxides for efficient HER.     

A new hyperbranched water-splitting technique based on Co3O4/MoS2 nano composite catalyst for High-Performance of hydrogen evolution reaction

Due to the extensive use of fossil fuels & their direct influence on the environment, new ways of producing energy sources are highly needed. Hydrogen is the perfect candidate for renewable energy; however, H₂ gas production is associated with disadvantages due to a lack of efficient and active catalysts that could be cost-effective and comparable to platinum performance. Active hydrogen evolution reaction catalysts are needed to advance the development of a cheaper generation of solar fuels. Thus, outperformance, and stable earth abundant. And inexpensive catalysts are highly demanded. That is H₂ gas production from the electrolysis of water through HER. In this work, we present different analytical techniques that characterize an efficient and highly stable catalyst based on transition metal oxide Co₃O₄/MoS₂ nanostructures. And their composites for water splitting in harsh acidic conditions time and material chemical composition as like SEM, EDS, XRD, HRTEM & XPS. The composite material is highly best to produce HER at 10 mA cm^?2 and obtained 268 mV overpotential of nano Co₃O₄/MoS₂ (S3) and Tafel slope of 56 mv/dec. Faraday efficiencies of the hydrogen gas production measured for the 60 min and catalyst is highly durable for the 20 h. The presented catalysts are up to the mark of platinum metal performance and superior to several transition metal oxides. This fabrication technology is a new roadmap for developing active and scalable hydrogen-evolving catalysts by overcoming the issues of fewer catalytic edges, low density, and poor conductivity.     

Ruthenium-manganese phosphide nanohybrid supported on graphene for efficient hydrogen evolution reaction in acid and alkaline conditions

Transition metal phosphides (TMPs) have been proved to be promising, economical and effective catalysts for hydrogen evolution reaction (HER). Precious metals with transition metals alloying can appropriately adjust the adsorption energy, which is an effective solution for greatly reducing the cost of noble metal catalysts and improving their inherent performance. Herein, a simple method was employed to synthesize MnRuPOGO-500 nano-catalysts with a particle size of about 5 nm, which showed excellent HER performance under both acid and basic media. In acidic solution, the optimal catalyst displayed the overpotential of HER to reach 10 mA cm^?2 with 109 mV, a small Tafel slope of 38.55 mV dec^?1 and long-time durability of 60 h. Especially in alkaline medium, the low overvoltage of 27 mV, a small Tafel slope of 57.35 mV dec^?1 and continuing stability of 48 h were further achieved. Meanwhile, we can find that manganese has negligible HER activity, but the doping of manganese generates a synergistic modulation effect in the MnP–Ru₂P alloy, thereby improving the HER performance of the catalyst. This paper brings a simple scheme and unique insights to the design of transition metals and platinum group metals (PGMs) phosphide alloy electrocatalysts.     

Three-demensional NiCoNiCo2O4/NF as an efficient electrode for hydrogen evolution reaction

At present, there is an urgent need for plentiful non-noble metal catalyst to substitute for valuableness platinum based metal catalyst in electrochemical water splitting. Here, we fabricated a three-demensional (3D) NiCoNiCo₂O₄ nanosheets electrocatalyst that directly grew on Ni foam firstly and then were reduced in 0.1 mol dm⁻³ sodium borohydride solution. This electrode exhibited high activity in 1.0 mol dm⁻³ KOH solution with an onset potential of ∼40 mV and a tafel slope of 77 mV dec⁻¹. Furthermore, the NiCoNiCo₂O₄/NF electrode showed a splendid durability during long-playing electrochemical test. Our work may provide an inexpensive, easy-to-obtain and excellent catalyst candidate for future electrolytic water research and industry studies that may involve hydrogen applications in the future.     

Autologous growth of Fe-doped Ni(OH)2 nanosheets with low overpotential for oxygen evolution reaction

Highly active and durable electrocatalysts for oxygen evolution reaction (OER) play a vital role in water splitting. Despite numerous efforts, the strategies to prepare durable and effective electrocatalysts via scalable methods still remain a great challenge. In this work, we fabricated Fe-doped Ni(OH)₂ ultrathin nanosheets (Fe–Ni–OH/Ni) via autologous growing of Ni(OH)₂ from Ni foam, and in situ electrochemical-assisted doping Fe into Ni(OH)₂. Benefiting from the unique structure with large surface areas and strong coupling effects between Fe and Ni, the optimal Fe–Ni–OH electrodes exhibit remarkable catalytic performance toward OER, which requires an overpotential of 220 mV to achieve a current density of 10 mA cm⁻² with a Tafel slope of 48.3 mV dec⁻¹. The Fe–Ni–OH electrodes also possess high stability even under a high current density of 500 mA cm⁻² for 600 h with an ultralow overpotential of 290 mV. Using Ni–Fe–OH electrodes as both anode and cathode for overall water splitting, only a small overpotential of 1.57 V is required to reach a current density of 10 mA cm⁻². Moreover, the high catalytic performance and scalable preparation method can meet the emergency needs for the practical application.     

Hydrothermal preparation of MoX2 (X = S,Se, Te)/TaS2 hybrid materials on carbon cloth as efficient electrocatalyst for hydrogen evolution reaction

The prominent features-based two-dimensional (2D) materials have proven themselves as efficient as well as robust electrocatalysts for the hydrogen evolution reaction (HER) owing to their low-cost, abundance and predominant conductivity. In this work, we report the synthesis of series of molybdenum chalcogenide nanostructures MoX₂ (X = S, Se, Te), hybridized with TaS₂ nanosheets, via a facile hydrothermal method, on self-supported carbon cloth electrode. Used as an electrocatalyst for HER, hybrid phase MoSe₂/TaS₂/CC electrode with a Mo/Se ratio of 1:1.5 exhibits the best HER performance, which could afford the benchmark current densities of 10 mA/cm² at the overpotentials of 75 mV with the measured Tafel slope values of 54.7 mV/dec. In addition, the presented molybdenum dichalcogenides in this work are also complimented with robustness as determined from durability and air stability measurements. The unique aspects of these unique hybrids, such as 1T and 2H phases hybridized MoS₂ and MoSe₂, semimetallic nature 1T′-MoTe₂ petal clusters and strong interface interaction between MoX₂ (X = S, Se, Te) and conductive TaS₂ nanosheets, cause superior HER catalytic performance.     

Tunably fabricated nanotremella-like Bi2S3/MoS2: An excellent and highly stable electrocatalyst for alkaline hydrogen evolution reaction

Reasonable design of efficient and stable catalysts with low cost and abundant natural reserves is vital for electrocatalytic water splitting. Herein, novel nanotremella-like Bi₂S₃/MoS₂ composites with different mass ratios between Bi₂S₃ and MoS₂ have been successfully prepared through a hydrothermal approach and further applied to hydrogen evolution reaction (HER) in 1.0 M KOH electrolyte for the first time. When the mass ratio of Bi₂S₃ and MoS₂ is 5:5, as-prepared nanotremella-like Bi₂S₃/MoS₂ (marked as BMS-5) manifests favorable HER catalytic activity with overpotential of 124 mV at current density of 10 mA cm⁻² and relatively low Tafel slope of 123 mV dec⁻¹. Moreover, it exhibits an extraordinary durability for uninterrupted hydrogen generation. The enhanced HER performances are ascribed to the synergistic effects between Bi₂S₃ and MoS₂, giving rise to large electrocatalytic active area and fast HER kinetics. The results pave a new path to design and construct excellent Bi₂S₃/MoS₂ nanomaterials for electrocatalytic hydrogen generation.     

Needle-like CoP/rGO growth on nickel foam as an efficient electrocatalyst for hydrogen evolution reaction

In this work, CoP/NF is synthesized at different temperature (250 °C, 300 °C, 350 °C) (denoted as CoP/NF-T, T = 250, 300, 350). Then, CoP/NF-300 with the best performance towards hydrogen evolution reaction (HER), is used to synthesize compounds with different ratio of reduced graphene oxide (rGO) (CoP/rGO/NF-X, X (quality ratio of rGO/CoP) = 1,3,5). In terms of morphology, under the synergistic effect of rGO, uniform and dense CoP provides the possibility to increase the electrochemical area. While CoP/rGO/NF-3 shows the minimum overpotential of 136 mV to drive 50 mA/cm, and the smallest Tafel slope 135 mV/dec among as-synthesized materials. Furthermore, CoP/rGO/NF-3 has good stability during at least 25 h. These result can be construed as the large electrochemical active area, high conductivity and long-time stability.     

Boosting electrocatalytic oxygen evolution activity by in-situ growth of hierarchical vertically-erected Ni(OH)2 nanosheets on Ag nanowires

A core-shell hierarchical nanoarchitecture consisting of Ni-layered double hydroxide nanosheets (Ni(OH)₂ NSs) grafted on Ag nanowires (Ag NWs) backbone is rationally designed and built by an in situ growth route, in which Ag NWs act as core and Ni(OH)₂ NSs as shell. The resulting hybrid material (Ag NW@Ni(OH)₂ NS), displayed a three-dimensional structure with a well-defined core-shell configuration and enlarged surface area, exhibits excellent electrocatalytic performance and enhanced durability. An electrochemical analysis exhibits that the Ag NW@Ni(OH)₂ NS-2H catalyst is a low overpotential of 290 mV required the achievement of a current density at 10 mA cm^?2 (j₁₀) and excellent long-term stability sustained over 24 h with only 6% potential increment at j₁₀ versus initial potential. Unique micro/macrostructure and synergistic effects are responsible for the extraordinary electrochemical performance of Ag NW@Ni(OH)₂ NS-2H core-shell composite. Ag NWs behave like a high conductive backbone due to their low intrinsic resistance, thus promoting charge transfer, whereas the hierarchical Ni(OH)₂ nanosheets, with huge surface area, provide a large number of active sites for oxygen evolution reaction, leading to enhanced electrochemical activity.     

Synergistic regulation of hydrogen adsorption/desorption via dual interfaces of Cu/Ni/Ni(OH)2 toward efficient hydrogen evolution reaction

Nickel-based catalysts have attracted tremendous attention as alternatives to precious metal-based catalysts for electrocatalytic hydrogen evolution reaction (HER) in virtue of their conspicuous advantages such as abundant reserves and high electrochemical activity. Nevertheless, a great challenge for Ni-based electrocatalyst is that nickel sites possess too strong adsorption for key intermediates H1, which severely suppresses the hydrogen-production activities. Herein, we report a hierarchical architecture Cu/Ni/Ni(OH)₂ consisting of dual interfaces as a high-efficient electrocatalyst for HER. The Cu nanowire backbone could provide geometric spaces for loading plenty of Ni sites and the formed Ni/Cu interface could effectively weakened the adsorption intensity of H1 intermediates on the catalyst surface. Moreover, the H1 adsorption could be further controlled to appropriate states by in-situ formed Ni(OH)₂/Ni interface, which simultaneously promotes water adsorption and activation, thus both Heyrovsky and Volmer steps in HER could be obviously accelerated. Experimental and theoretical results confirm that this interface structure can promote water dissociation and optimize H1 adsorption. Consequently, the Cu/Ni/Ni(OH)₂ electrocatalyst exhibits a low overpotential of 20 mV at 10 mA cm^?2 and an ultralow Tafel slope of 30 mV dec^?1 in 1.0 M KOH, surpassing those of reported transition-metal-based electrocatalysts and even the prevailing commercial Pt/C.