Ni–P alloy@carbon nanotubes immobilized on the framework of Ni foam as a 3D hierarchical porous self-supporting electrode for hydrogen evolution reaction

The development of self-supporting electrodes that exhibited both high efficiency and good durability remained a challenge in the field of hydrogen energy utilisation. Here, we designed a self-supporting 3D hierarchical porous electrode by filling carbon nanotubes (CNTs) loaded with Ni–P alloy into the framework of nickel foam (NF). Firstly, CNTs were decorated with a catalytically active Ni–P alloy via electroless plating (Ni–P@CNTs). Then, the Ni–P@CNTs were filled and anchored onto the framework of NF via electroplating to synthesise a self-supporting electrode (Ni–P@CNTs/NF). The Ni–P@CNTs/NF exhibited an excellent catalytic performance toward the hydrogen evolution reaction (HER) in 1 M KOH electrolyte, with an overpotential of 53 mV at 10 mA cm^?2, a small Tafel slope of 101.56 mV dec^?1 and excellent long-term durability. This facile and effective strategy might provide a new path to the design of self-supporting electrodes with enhanced HER catalytic.     

3D hierarchical nanostructured Ni–Co alloy electrodes on porous nickel for hydrogen evolution reaction

Nanostructured Ni–Co alloys decorated on 3D porous nickel electrodes for hydrogen evolution reaction (HER) are successfully prepared through a facile and effective electrodeposition method. By adjusting the current density of electrodeposition, Ni–Co alloys with different surface morphologies like nanocones, leaf-like structures and flakes can be obtained. The HER catalytic activity has been greatly reinforced with decorated Ni–Co alloys. Meanwhile, the HER performance of nanocone Ni–Co alloys outperforms that of leaf-like and flaky Ni–Co alloys. The nanocone Ni–Co alloys exhibit outstanding HER activity, only requiring an overpotential of 86.7 mV at 10 mA cm⁻², along with a low Tafel slope of 69.8 mV dec⁻¹ and 3.4 Ω charge transfer resistance. This nanocone electrode remains stable for 10 h of chronopotentiometric measurement. Such enhanced catalytic performance stems from the porosity and the high population of sharp edges, as well as surface oxidation/metallic states and synergistic effects between Ni and Co.     

Ni,Zn Co-doping ZIF-67-derived electrocatalyst based on CNT film for efficient overall water splitting

Water electrolysis has been acknowledged as a renewable, scalable, and effective way of producing hydrogen. However, for water splitting, efficient and noble metal-free electrocatalysts were lacking. Here, a Co–Ni–Zn porous three-dimension N-doped carbonization structure on the carbon nanotube film (CNTF) was synthesized through a metal organic frameworks (MOFs) annealing procedure. The porous morphology, caused by the evaporation of zinc at high temperatures, enhances the interaction between the catalysts and electrolyte, and the self-supporting structure minimizes the contact resistance between the catalysts and the substrate, which reduces obstructions during current flow. More active sites, multiple mesopores, and high conductivity are all features of this composite structure. It can achieve a small overpotential of 112 mV and 270 mV at a current density of 10 mA cm⁻², respectively, for hydrogen and oxygen evolution reactions (HER and OER). At a current density of 10 mA cm⁻², the Co–Ni–Zn/NCNTF has an external voltage of 1.58 V and is very durable for overall water splitting.     

Electroless deposition of Ni–Cu–P on a self-supporting graphene with enhanced hydrogen evolution reaction activity

With the increasing issues of the energy crisis and environmental pollution, the development of clean energy has become an urgent task. Herein, self-supporting graphene (SSG) that could serve as the three-dimensional catalyst support is developed by electrochemically intercalating the flexible graphite paper (FGP) in 1 M KOH. Then, the Ni-base alloy is deposited on the SSG by electroless plating. The resulting electrode (Ni–Cu–P/SSG) exhibits excellent hydrogen evolution reaction (HER) electrocatalytic performance in 1 M KOH. The Ni–Cu–P/SSG catalyst just requires the overpotentials of 75 and 219 mV to reach 10 and 100 mA cm⁻², respectively. Besides, the Ni–Cu–P/SSG still maintains superior HER catalytic activity after the stability test of 12 h. The Ni–Cu–P/SSG composite catalyst with high catalytic activity, remarkable stability and facile preparation method has a significant influence on the extension of renewable energy preparation and application.     

In-situ “encapsulation” of Mo:Mo2C with nano-mosaic structure on wood-derived carbon for hydrogen evolution reaction

Coupling metallic and Mo₂C phases uniformly on conductive matrix at nanoscale is a promising route to solve the poor electrical conductivity and aggregation problems of nano-Mo₂C. In this work, a 3D self-supporting carbonized wood (CW) electrode encapsulation with mosaic structure Mo:Mo₂C for hydrogen evolution reaction was fabricated successfully by a facile annealing treatment and a gas-solid reaction. The presence of Mo phase accelerated the transfer rate of electrons and provided heterogeneous interface. The obtained electrode shows abundant catalytic active sites and low electrochemical impedance, thus improving the catalytic process of splitting water for HER. The Mo:Mo₂C-775 electrode requires an overpotential of 73.5 mV and 117 mV to achieve the current density of 10 mA cm^?2 in 0.5 M H₂SO₄ and 1.0 M KOH, respectively. Moreover, Mo:Mo₂C-775 electrode displayed excellent stability performance, which almost maintained a constant current density for 12 h (at ?100 mV vs RHE) in 0.5 M H₂SO₄ and 1.0 M KOH, respectively. This study provides a new idea for preparation of efficient 3D self-supporting electro-catalyst for HER.     

Transition metal doped MoS2 nanosheets for electrocatalytic hydrogen evolution reaction

In the present work, the effect of transition metals (Ni, Fe, Co) doping on 2-dimensional (2D) molybdenum disulfide (MoS₂) nanosheets for electrocatalytic hydrogen evolution reaction (HER) was explored. A simple and cost-effective hydrothermal method was adopted to synthesis transition metals doped MoS₂ nanosheets. The morphological and spectroscopic studies evidence the formation of high-quality MoS₂ nanosheets with the randomly doped metal ions. Notably, the Ni–MoS₂ displayed superior HER performance with an overpotential of ?0.302 V vs. reversible hydrogen electrode (RHE) (to attain the current density of 10 mA cm^?2) as compared to the other transition metals doped MoS₂ (Co–MoS₂, Fe–MoS₂). From the Nyquist plot, superior charge transport from the electrocatalyst to the electrolyte in Ni–MoS₂ was realized and confirmed that Ni doping provides the necessary catalytic active sites for rapid hydrogen production. The stable performance was confirmed with the cyclic test and chronoamperometry measurement and envisaged that hydrothermally synthesized Ni–MoS₂ is a highly desirable cost-effective approach for electrocatalytic hydrogen generation.     

CoP/Ni2P heteronanoparticles integrated with atomic Co/Ni dual sites for enhanced electrocatalytic performance toward hydrogen evolution

Transition metal phosphides (TMPs) have attracted considerable attention as an advanced electrocatalyst for hydrogen evolution reaction (HER). Nevertheless, the catalytic efficiency of single-component TMPs is still restricted that cannot endure long-term running and easy to be corroded especially under harsh conditions. In this work, a multicomponent electrocatalyst combined with CoP/Ni₂P heteronanoparticles and Co/Ni single-atom active sites (denoted as N–C@CoP/Ni₂P) is rational designed and prepared. The obtained N–C@CoP/Ni₂P electrode material exhibits enhanced performance with the overpotential of 153 mV at 10 mA cm^?2, and the small Tafel value of 53.01 mV dec^?1 in 0.5 M H₂SO₄, and a satisfied result is obtained in basic media as well. The outstanding HER performance is mainly benefiting from the synergistic effect between CoP and Ni₂P, and the highly catalytic faction of atomic Co/Ni dual sites. Furthermore, a powerful conductive network fabricated by N-doped carbon skeleton and in-situ grown CNTs improves the conductivity of catalyst. Such a stereoscopic 3D nanostructure is also facile to accelerate the shuttle of electrons and ions.     

Iron doped mesoporous cobalt phosphide with optimized electronic structure for enhanced hydrogen evolution

We report a self-supporting electrode fabricated by covering iron doped mesoporous cobalt phosphide film on carbon cloth substrate (meso-Fe_xCo_1-xP/CC) for hydrogen evolution reaction (HER). In acidic and alkaline electrolytes, the electrode exhibited excellent catalytic activity and fast kinetics towards the HER, only requiring small overpotentials of 61 mV and 67 mV to drive 10 mA cm^?2, respectively. The superior electrocatalytic activity is attributed to the mesoporous structure with high specific surface area (147.5 m² g^?1) and doping of Fe atom. The mesoporous structure grown on the conductive carbon cloth substrate enables the fully exposure of active sites and the rapid penetration of electrolyte. Additionally, density functional theory (DFT) calculation reveals that the doping of Fe enhances the adsorption of H atoms by shifting the d-band center of Co. Meanwhile, the introduction of Fe lowers the energy barrier for water dissociation, which accelerates the catalytic kinetics in alkaline electrolyte.     

Nickel-based nanosheets array as a binder free and highly efficient catalyst for electrochemical hydrogen evolution reaction

Hydrogen technology through water electrolyzer systems has attracted a great attention to overcome the energy crisis. So, rationally designed non-noble metal based-electrocatalysts with high activity and durability can lead to high performance water electrolyzer systems and high purity hydrogen generation. Herein, a facile two-step method: hydrothermal and electrodeposition, respectively, are developed to decorate highly porous three-dimensional binder-free structure NiFeO/NiO nanosheets array on Ni foam (NiFeO/NiO/NF) with robust adhesion as a high-performance electrode for Hydrogen Evolution Reaction (HER).The electrodeposition process applied after the initial hydrothermal process provides a stable structure and, in addition, enhances the sluggish hydrogen evolution efficiency. In alkaline media, the developed electrode needs an overpotential of 48 and 188 mV to drive current densities (j) of 10 and 100 mA cm^?2, respectively. After continuous 110 h electrochemical stability test under j = 150 mA cm^?2 conditions, demonstrates an excellent stability with ignorable activity decrease. Such superior HER catalytic performance can be derived from the synergistic effect between Ni and Fe atoms, also exposure to a high number of active sites on the nanosheets, and good dynamic with effective electron transport along the nanosheets. The present work provides a promising route for the design and fabrication of cost-effective and highly efficient HER electrocatalysts.     

Nickel-doped MoSe2 nanosheets with Ni–Se bond for alkaline electrocatalytic hydrogen evolution

Molybdenum diselenide (MoSe₂) is a potential catalytic material for the electrocatalytic hydrogen evolution reaction (HER). However, due to the low density of its active sites, MoSe₂ nanosheets feature high overpotential in HER, which limits its practical application. This describes the method of doping the Ni in MoSe₂ nanosheets to increase active sites. The NiO₂ evenly dispersed on MoSe₂ by ethanol solution reduces to ~4 nm Ni nanoclusters under annealing process, which is firmly adhered to MoSe₂ nanosheets with Ni–Se bond. The electrochemical active surface area of Ni-doped MoSe₂ expands, proving that Ni dopants produce more activity sites in MoSe₂ nanosheets. The overpotential of MoSe₂ (at 10 mA cm⁻²) decreases from 335 mV to 181 mV with 4.5 at.% Ni doped in 1 M KOH. The Ni–MoSe₂ also characterizes excellent stability for 12 h with the formation of Ni–Se bond. The study of doping Ni in MoSe₂ nanosheets is of great guiding significance to the design and production of non-noble electrocatalysts for HER in alkaline media.     

Electrodeposition of Ni–Fe–Mn ternary nanosheets as affordable and efficient electrocatalyst for both hydrogen and oxygen evolution reactions

The synthesis of high performance and economical electrocatalysts in the process of overall water splitting is very important for the production of hydrogen energy and has become one of the most important challenges. Here, various Ni, Ni–Fe, Ni–Mn nanosheets and Ni–Fe–Mn ternary nanosheets were created using cost-effective, versatile and binder-free electrochemical deposition methods, and the electrocatalytic activity of various electrodes for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) were investigated in an alkaline environment. Due to the high electrochemical active surface area due to the fabrication of nanosheets, the synergistic effect between different elements on the electronic structure, the high wettability due to the formation of nanosheets and the quick detachment of formed gasses from the electrode, the Ni–Fe–Mn nanosheets electrode showed excellent electrocatalytic activity. In order to deliver the 10 mA cm⁻² current density in HER and OER processes, this electrode required values of 64 mV and 230 mV overpotential, respectively. Also, the stability test showed that after 10 h of electrolysis at a current density of 100 mA cm⁻², the overpotential changes was very small (less than 4%), indicating that the electrode was excellent electrostatic stability. Also, when using as a bi-functional electrode in the full water splitting system, it only needed a cell voltage of 1528 V to deliver a current of 10 mA cm⁻². The results of this study indicate a new strategy for the synthesis of active and stable electrocatalysts.     

Partial phosphorization of porous Co–Ni–B for efficient hydrogen evolution electrocatalysis

Design of cost-effective and high-efficient electrocatalysts for hydrogen evolution reaction (HER) is of vital significance for the current renewable energy devices — fuel cells. Herein, we report a facile strategy to prepare partial phosphorization of Co–Ni–B material with porous structure via a water-bath boronizing and subsequent phosphorization process at moderate temperature. The optimal atomic proportion of Co to Ni is investigated via physical and electrochemical characterization. As a result, Co₉–Ni₁–B–P exhibits the best HER activity, which require an lower overpotential of ~192 mV to deliver a current density value of 10 mA cm⁻² and a smaller Tafel slope of 94 mV dec⁻¹ in alkaline media, relative to P-free Co–Ni–B catalysts, Co₉–Ni₁–B–P with other Co: Ni proportion and mono metallic borides The excellent electrocatalytic performance of Co₉–Ni₁–B–P is mainly ascribed to the three-dimensional (3D) porous structure and the coordinate functionalization between the borides and phosphides. This work provides a promising strategy for the exploration of quaternary composites as efficient and cost-effective electrocatalysts for HER.     

Hybrid niobium and titanium nitride nanotube arrays implanted with nanosized amorphous rhenium–nickel: An advanced catalyst electrode for hydrogen evolution reactions

The scalable application of high-performance electrocatalysts with fine nanostructures for hydrogen evolution reactions (HER) depends on the development of durable and active electrode supports. Transition metal nitrides are considered as candidates due to their high conductivity, favorable catalytic activity, and excellent chemical stability in acidic or alkaline aqueous solutions. The present work proposed to fabricate self-ordered hybrid niobium–titanium (Nb–Ti) nitride nanotube arrays (NNAs) on Nb–Ti alloy panels by an anodization and subsequent nitridation process. Results showed that the highly ordered NNA is composed of mixed Nb₄N₅ and TiN and has merits of super hydrophilicity, outstanding corrosion resistance, and high conductivity. On the basis of the successful synthesis of Nb–Ti NNA, the nano–sized amorphous rhenium–nickel (Re–Ni) alloy was electrodeposited onto the NNA support, forming the Re–Ni/NNA composite electrode. Electrochemical tests exhibited that the Re–Ni/NNA composite electrode can provide a current density of 50 mA cm⁻² in 1.0 M KOH at a potential of −0.18 V vs. RHE and maintain stability in a testing period of 100 h. This superior HER performance is attributed to the combination of Re–Ni particles and Nb–Ti NNA support, which can benefit the diminution of charge transfer resistance and the improvement of catalytic activity.     

Synthesis of ZIF-8 derived porous carbon/NiS hexahedral composite and its application in improving the electrochemical hydrogen storage properties of Co–P material

Thermal treatment of zinc-based MOF (ZIF-8) is conducted to prepare ZIF-8 derived porous carbon (ZIF-8-C). ZIF-8-C/NiS hexahedral composites with different C/Ni mole ratios (C@NiS-2, C@NiS-4 and C@NiS-6) are synthesized by solvothermal method. Co–P hydrogen storage material is prepared via mechanical alloying. Then, composites of Co–P coated with NiS, ZIF-8-C and C@NiS are obtained by ball-milling. Eventually, C@NiS-4 coated Co–P electrode exhibits higher discharge capacity of 624.8 mAh/g than separate NiS or ZIF-8-C modified Co–P and original Co–P electrodes. The HRD, corrosion resistance and kinetics properties of Co–P are also improved after C@NiS-4 loading. The enhanced kinetics performance and electrochemical activities of Co–P + C@NiS-4 may be due to the synergistic effect between flexible porous carbon ZIF-8-C and active NiS nanosheets, which can further accelerate the hydrogen diffusion during the charging/discharging processes.     

NiCoP–CoP heterostructural nanowires grown on hierarchical Ni foam as a novel electrocatalyst for efficient hydrogen evolution reaction

The design and manufacture of effective non-noble metal catalysts for the H₂ evolution reaction (HER) are urgent for realizing a cost-effective hydrogen production. We report herein on flower-like structures consisting of NiCoP–CoP heterostructural nanowires grown directly on the hierarchically porous nickel framework (NiCoP–CoP/Ni/NF) to achieve a highly efficient HER in alkaline solution (1.0 M KOH). The NiCoP–CoP/Ni/NF is synthesized by electrodeposition of porous Ni layers on Ni foam, followed by simple hydrothermal reaction and phosphorization. For HER, the binder-free NiCoP–CoP/Ni/NF electrode can reach 10 mA cm^?2 current density at a quite low overpotential of 49 mV, because of the combination of porous Ni layers and highly active NiCoP–CoP nanowires. In addition, the NiCoP/CoP heterostructures exhibited remarkable stability under the long-term durability test. This work provides a new strategy that combines electrodeposition and hydrothermal reaction to synthesize effective HER catalysts.     

Bifunctional electrocatalysts for water splitting from a bimetallic (V doped-NixFey) Metal–Organic framework MOF@Graphene oxide composite

An ongoing challenge still lies in the exploration of proficient electrocatalysts from earth-abundant non-precious metals instead of noble metal-based catalysts for clean hydrogen energy through large-Scale electrochemical water splitting. However, developing a non-precious transition metals based, stable electrocatalyst for cathodic hydrogen evolution reaction (HER) and anodic oxygen evolution reaction (OER) is important challenge for modern energy conversion technology. In this report Vanadium doped bimetallic nickel-iron nanoarray, fabricated by carbon supported architecture through carbonization process for electrochemical water splitting. Three types of catalysts were prepared in different molar ratio of Ni/Fe. The electrocatalytic performance demonstrated that the catalyst with equal mole ratio (0.06:0.06) of Ni/Fe possess high catalytic activity for both OER and HER in alkaline and acidic medium. Besides, our findings revealed that the doping of vanadium could play a strong synergetic effect with Ni/Fe, which provide a small overpotential of 90 mV and 210 mV at 10 mA cm^?2 for HER and OER respectively compared to the other two catalyst counterparts. Also, the catalyst with 1:1 (Ni/Fe) molar ratio showed a high current density of 208 mA cm^?2 for HER at 0.5 M H₂SO₄ and 579 mA cm^?2 for OER at 1 M KOH solution, the both current densities are much higher than the other two catalysts (different Ni/Fe ratio). In addition, the presented catalysts showed extremely good durability, reflecting in more than 20 h of consistent Chronoamprometry study at fixed overpotential η = 250 mV without any visible voltage elevation. Similarly, the (Ni/Fe) equal ratio catalyst showed better corrosion potential 0.209 V vs Ag/AgCl and lower current density 0.594 × 10^?12 A cm^?2 in high alkaline medium. The V-doping, MOF/GO surface defects are significantly increased the corrosion potential of the V-Ni_xFe_y-MOF/GO electrocatalyst. Besides, the water electrolyzed products were analysed by gas chromatography to get clear insights on the formed H₂ and O₂ products.     

A bi-functional Co–Ni layered double hydroxide three-dimensional porous array electrode derived from ZIF-L(Co)@ZIF-L(Co,Ni) for oxygen evolution reaction and supercapacitors

Developing high-efficiency bifunctional materials for electro-catalysis and supercapacitors are urgently needed but challenging. Herein, we develop a self-supporting Co–Ni LDH electrode prepared by in-situ growing ZIF-L(Co)@ZIF-L(Co, Ni) on carbon paper followed by a pseudomorphic transformation. The optimized Co–Ni LDH/carbon paper electrodes (CN-2/CP) exhibit excellent electrochemical activity and stability in oxygen evolution reactions (OER) and supercapacitors. The CN-2/CP electrode displays a low overpotential of 230 mV at 10 mA cm^?2 and superior stability at 40-h chronopotentiometry for OER. For supercapacitor, the CN-2/CP electrode delivers a high specific capacitance of 1346 F g^?1 at 1 A g^?1 and maintains a capacitance of 88.5% after 7000 charge/discharge cycles at 20 A g^?1. Based on the physical and chemical characterization results, the high performance originates from the in-situ electrochemical conversion of metal hydroxide, improved conductivity, fast charge transfer at the interface and unique layered cross morphology providing more active sites.     

Electrocatalysis property of CuZn electrode with Pt and Ru decoration

Electrocatalysis properties strongly depend on the interaction of metallic particles and this interaction enables to change the electronic structure of alloys which enhances the catalytic activity. This property is the key factor in the developing of cost-effective and efficient Hydrogen Evolution Reaction (HER) electrocatalysts for sustainable hydrogen production. In this study, novel electrocatalysts which are decorated with Pt and Ru have been developed for HER electrocatalysis. Microscopic analysis such as scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray diffraction (XRD) and atomic force microscopy (AFM) are performed to determine the morphological and compositional structures. Electrocatalysis properties are evaluated by cathodic current-potential curves, electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) in 1.0 M KOH solution. Chronoamperometry (CA) and cycle tests are used for stability/durability of electrocatalysts. Results show that a small onset potential of the porous Cu/Ni/CuZn–Pt is obtained for HER. Exchange current density and polarization resistance are found to be 5.39 mA cm^?2 and 2.0 Ω cm² at overpotential of ?100 mV for porous Cu/Ni/CuZn–Pt, respectively, indicating that Cu/Ni/CuZn–Pt is higher electrocatalytic properties than the others. Moreover, very low overpotentials at 10 and 40 mA cm^?2 are obtained on porous Cu/Ni/CuZn–Pt compared with porous Cu/Ni/CuZn–Ru and Cu/Ni/CuZn. Porous Cu/Ni/CuZn–Pt also displays excellent stability/durability in test solution. The remarkable electrocatalysis properties of porous Cu/Ni/CuZn–Pt can be explained due to high porous structure, leaching of Zn from the deposit, intrinsic activity of Pt as well as changing in the electronic structure. It should be considered that porous Cu/Ni/CuZn–Pt is of high corrosion resistance in test solution for 120 h, which makes it good candidate for HER.     

Electrodeposited porous spherical Ni(OH)2@Ni on carbon paper for high-efficiency hydrogen evolution

Exploring noble-free electrocatalyst for hydrogen evolution by electrolysis of water is significant. Herein, porous Ni(OH)₂@Ni spherical particles are electrodeposited on carbon papers as efficient electrocatalysts for hydrogen evolution reaction (HER) from water. Due to the porous and composite structure, the HER activity of Ni(OH)₂@Ni/CP is better than the single phase Ni or Ni(OH)₂ particles on the carbon paper. The overpotential of Ni(OH)₂@Ni/CP is 106 mV at the current density of 10 mA cm^?2 and the Tafel slope is 88 mV dec^?1. Moreover, the stability of the catalysts tested for 12 h is also good for HER. Furthermore, the small R_ct (1.65 Ω) of Ni(OH)₂@Ni/CP provides the evident for its excellent catalytic performance. The method of electrodeposition provides the controllable uniform size for porous spherical Ni(OH)₂@Ni particles. Moreover, the Faradaic efficiency for hydrogen evolution is 100%.     

In situ Raman spectroscopic study towards the growth and excellent HER catalysis of Ni/Ni(OH)2 heterostructure

The electrochemical water splitting to produce H₂ in high efficiency with earth-abundant-metal catalysts remains a challenge. Here, we describe a simple “cyclic voltammetry + ageing” protocol at room temperature to activate Ni electrode (AC-Ni/NF) for hydrogen evolution reaction (HER), by which Ni/Ni(OH)₂ heterostructure is formed at the surface. In situ Raman spectroscopy reveals the gradual growth of Ni/Ni(OH)₂ heterostructure during the first 30 min of the aging treatment and combined with polarization measurements, it suggests a positive relation between the Ni/Ni(OH)₂ amount and HER performance of the electrode. The obtained AC-Ni/NF catalyst, with plentiful Ni–Ni(OH)₂ interfaces, exhibits remarkable performance towards HER, with the low overpotential of only 30 mV at a H₂-evolving current density of 10 mA/cm² and 153 mV at 100 mA/cm², as well as a small Tafel slope of 46.8 mV/dec in 1 M KOH electrolyte at ambient temperature. The excellent HER performance of the AC-Ni/NF could be maintained for at least 24 h without obvious decay. Ex situ experiments and in situ electrochemical-Raman spectroscopy along with density functional theory (DFT) calculations reveal that Ni/Ni(OH)₂ heterostructure, although partially reduced, can still persist during HER catalysis and it is the Ni–Ni(OH)₂ interface reducing the energy barrier of H1 adsorption thus promoting the HER performance.