Bifunctional Electrocatalysts For Water Splitting Research Articles

Economic and binder-free synthesis of NiCo2O4 nanosheets on a Flexible stainless steel mesh as a bifunctional electrode for water splitting

Water as a green source of hydrogen has attracted the attention of researchers considering its potential applications in the energy sector. Thus, developing efficient bifunctional electrocatalysts for water splitting is a potential challenge perceived by researchers exploring the development of sustainable energy technologies. With this motive, the present study focuses on the preparation of the highly active, economic, binder-free, and bifunctional NiCo2O4 nanosheets@ Flexible Stainless Steel Mesh substrate (NCO@FSSM) electrocatalyst via reflux condensation method for the bulk O2 and H2 production. The influence of reflux condensation temperatures (100, 120, 140 °C) on the morphology and electrocatalytic activity is investigated. Electrocatalytic properties for NCO@FSSM synthesized at 120 °C were noted exhibiting smaller overpotentials for oxygen evolution reaction (OER, 310 mV) and hydrogen evolution reaction (HER, 79 mV) at 10 mA cm−2, which were lowest among the previously reported Ni, and Co-based electrodes. Additionally, the scale-up experiments with NCO-120@FSSM film (8 cm X 8 cm) as an anode and FSSM as a cathode and vice-versa, in a specially designed scale-up electrochemical cell revealed steady electrocatalytic performance. The real-time water splitting was studied for 25 h and was noted to produce 7.4 L of (O2) and 11.5 L of hydrogen (H2).

Compositional engineering of HKUST‐1/sulfidized NiMn‐LDH on functionalized MWCNTs as remarkable bifunctional electrocatalysts for water splitting

AbstractWater‐splitting reactions such as the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) typically require expensive noble metal‐based electrocatalysts. This has motivated researchers to develop novel, cost‐effective electrocatalytic systems. In this study, a new multicomponent nanocomposite was assembled by combining functionalized multiwalled carbon nanotubes, a Cu‐based metal–organic framework (MOF) (HKUST‐1 or HK), and a sulfidized NiMn‐layered double hydroxide (NiMn‐S). The resulting nanocomposite, abbreviated as MW/HK/NiMn‐S, features a unique architecture, high porosity, numerous electroactive Cu/Ni/Mn sites, fast charge transfer, excellent structural stability, and conductivity. At a current density of 10 mA cm−2, this dual‐function electrocatalyst shows remarkable performance, with ultralow overpotential values of 163 mV (OER) or 73 mV (HER), as well as low Tafel slopes (57 and 75 mV dec−1, respectively). Additionally, its high turnover frequency values (4.43 s−1 for OER; 3.96 s−1 for HER) are significantly superior to those of standard noble metal‐based Pt/C and IrO2 systems. The synergistic effect of the nanocomposite's different components is responsible for its enhanced electrocatalytic performance. A density functional theory study revealed that the multi‐interface and multicomponent heterostructure contribute to increased electrical conductivity and decreased energy barrier, resulting in superior electrocatalytic HER/OER activity. This study presents a novel vision for designing advanced electrocatalysts with superior performance in water splitting. Various composites have been utilized in water‐splitting applications. This study investigates the use of the MW/HK/NiMn‐S electrocatalyst for water splitting for the first time to indicate the synergistic effect between carbon‐based materials along with layered double hydroxide compounds and porous compounds of MOF. The unique features of each component in this composite can be an interesting topic in the field of water splitting.

Bimetallic NiO/NiFe2O4 heterostructures with interfacial effects for boosting electrochemical water splitting applications

The present work reports the simple preparation of NiO/ NiFe2O4 heterostructures with interfacial effects as bifunctional electrocatalysts for overall water splitting. At increasing Ni/Fe precursor ratios, the evolution of NiO phases is observed in NFO heterostructures, which incorporate differential strain effects at the interface. The modulated heterojunction of NiO/NiFe2O4 heterostructure incorporates compressive strain at the interfaces enhancing its electrocatalytic performances. Notably, NiO/NiFe2O4 heterostructure prepared at equimolar Ni/Fe ratios (NFO-1) exhibits significant electrocatalytic performances due to modulated interfacial effects. As such, NFO-1 exhibits lower OER and HER overpotentials of about 242 mV and 106 mV for 10 mA cm−2 current density and exhibits improved water splitting activity, requiring 1.56 V to drive 10 mA cm−2 current density. The present work emphasizes the importance of modulating the heterostructures of transition metal oxides to enhance the interfacial effects as bifunctional electrocatalysts for water splitting applications.

Component Engineering of Multiphase Nickel Sulfide-Based Bifunctional Electrocatalysts for Efficient Overall Water Splitting

The development of highly efficient and low-cost bifunctional electrocatalysts for water splitting has become increasingly attractive. So far, the strategies to optimize electrocatalytic performance have mainly focused on enhancing the active sites and regulating the surface structures through doping foreign metal or anions into the composites; however, the internal and external adjustments achieved by tuning the chemical composition and crystalline phases in a material in order to investigate the composition-dependent catalytic activity has generally remained limited. Here, through various in situ composition-dependent nickel sulfides grown while controlling the sulfidation degree, we achieve the precise regulation of nickel sulfides from a single-phase component to multiple-phase components (i.e., two-phase components and three-phase components), further comparing the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) performances. Benefiting from the synergy of an analogous uniform nanoarray structure and excellent intrinsic activation, the as-obtained NixSy-5, with three-phase components, shows low overpotentials at 10 mA cm−2 for HER (148 mV) and OER (111 mV), as well as a low cell voltage of 1.48 V for overall water splitting in alkaline media, which are among the best results ever reported for overall water splitting.

Cobalt Polyoxometalates Anchored on Nife‐LDH Nanoplates as Highly Active and Stable Bifunctional Catalysts for Overall Water Splitting

AbstractDesigning efficient and bifunctional electrocatalysts for water splitting conforms to the concept of energy conservation and emission reduction but remains challenging now. Herein, the fabrication of a heterostructure by anchoring cobalt‐polyoxometalates (Co‐POM) on NiFe layered double hydroxide (NiFe‐LDH) nanoplates in situ on nickel foam (NF) is first reported (Co‐POM@LDH/NF). The surface area, electron transfer ability, and stability of the heterostructure are increased due to the synergistic effect between Co‐POM and NiFe‐LDH. Particularly, Co‐POM@LDH/NF can deliver a current density of 100 mA cm−2 with an overpotential of only 220 mV for hydrogen evolution reaction (HER) and 226 mV for oxygen evolution reaction (OER) in 1.0 m KOH electrolytes. Impressively, the outstanding stability of Co‐POMs in heterostructures is verified by the experimental observations after electrolysis, indicating the successful construction of stable POMs‐based heterogeneous electrocatalysts. More attractively, the electrolyzer composed by Co‐POM@LDH/NF as anode and cathode shows a much lower operating voltage of 1.51 V at the current density of 10 mA cm−2 for overall water splitting. This study provides a feasible and extensible idea for the design of the POM‐based heterostructures.

Bifunctional electrocatalyst for water splitting based on thermally exfoliated amorphous and ball mill derived nitrogen doped crystalline Cr2O3

Facile preparation of non-noble bifunctional electrocatalysts with high performance, durability, and low cost are helpful to render water splitting viable on scale. However, this remains a challenge. Herein, we report the synthesis and catalytic activity of rapid thermally exfoliated amorphous and ball milled crystalline nitrogen doped Cr2O3 (N:Cr2O3). The materials are tested for electrocatalytic OER and HER activity for the first time. Ball milling results in a phase transition from amorphous to crystalline while also bringing about nitrogen doping in Cr2O3 material. N:Cr2O3 exhibit an OER overpotential of 398 mV at a current density of 10 mA/cm2. Furthermore, it offers good stability for over 22 h in an alkaline medium. In HER, the material gives an overpotential of 182 mV at 10 mA/cm2 and a Tafel slope of 115 mV/dec. N:Cr2O3 possess high electrochemical stability (>20 h) in harsh alkaline conditions, thereby opening a new avenue for developing novel and viable catalysts.

Electronic optimization of heterostructured MoS2/Ni3S2 by P doping as bifunctional electrocatalysts for water splitting

MoS2 is an excellent catalyst for hydrogen evolution reaction (HER) because of its close proximity to the optimum hydrogen adsorption free energy (ΔGH*). However, poor oxygen evolution reaction (OER) intrinsic activity, insufficient active sites, and poor conductivity hinder its application as a bifunctional electrocatalyst. Here, Ni3S2 is combined with MoS2 forming MoS2/Ni3S2 heterostructure due to its intrinsic OER activity and P is chosen as an anion dopant to optimize ΔGH* due to its near-thermoneutral H adsorption to explore the bifunctional performance of MoS2 based nanocomposites. The electronic configurations of Mo, Ni, and S on the interface are modulated by P doping, which optimizes their adsorption/desorption ability of intermediates. The synergistic effect of anion doping and heterostructure induces excellent catalytic activity in P40-MoS2/Ni3S2–5 (Mo to S molar ratio of 1:5 and 40 mg P dopants) with overpotentials of 142 mV for HER and 278 mV for OER at 100 mA cm−2 in 1.0 M KOH solution. The voltage of overall water splitting is 1.76 V using P40-MoS2/Ni3S2–5 as the anode and cathode. This work elucidates a method of optimizing the electronic structure by doping P anion in heterointerface, providing an avenue to boost the catalytic activity of non-noble metal-based catalysts.

Facile Synthesis of Co Nanoparticles Embedded in N-Doped Carbon Nanotubes/Graphitic Nanosheets as Bifunctional Electrocatalysts for Electrocatalytic Water Splitting.

Developing robust and cost-effective electrocatalysts to boost hydrogen evolution reactions (HERs) and oxygen evolution reactions (OERs) is crucially important to electrocatalytic water splitting. Herein, bifunctional electrocatalysts, by coupling Co nanoparticles and N-doped carbon nanotubes/graphitic nanosheets (Co@NCNTs/NG), were successfully synthesized via facile high-temperature pyrolysis and evaluated for water splitting. The morphology and particle size of products were influenced by the precursor type of the cobalt source (cobalt oxide or cobalt nitrate). The pyrolysis product prepared using cobalt oxide as a cobalt source (Co@NCNTs/NG-1) exhibited the smaller particle size and higher specific surface area than that of the pyrolysis products prepared using cobalt nitrate as a cobalt source (Co@NCNTs/NG-2). Notably, Co@NCNTs/NG-1 displayed much lower potential -0.222 V vs. RHE for HER and 1.547 V vs. RHE for OER at the benchmark current density of 10 mA cm-2 than that of Co@NCNTs/NG-2, which indicates the higher bifunctional catalytic activities of Co@NCNTs/NG-1. The water-splitting device using Co@NCNTs/NG-1 as both an anode and cathode demonstrated a potential of 1.92 V to attain 10 mA cm-2 with outstanding stability for 100 h. This work provides a facile pyrolysis strategy to explore highly efficient and stable bifunctional electrocatalysts for water splitting.

Synergistic electronic structure tuning of self-assembled hollow hierarchical Ni-Fe-Co-P nanowire arrays on carbon cloth for enhanced water splitting

The pursuit of efficient and durable catalysts utilizing non-noble metals is critical for sustainable energy conversion through electrochemical water splitting. Herein, we present a novel bifunctional electrocatalyst of Ni-Fe-Co-P nanowire arrays on carbon cloth for overall water splitting, which was synthesized via a facile ion-exchange reaction between Co-MOF nanowires array and Fe2+/Ni2+ ions, followed by NaH2PO2-assisted phosphorization. By carefully controlling the molar ratios of Ni2+/Fe2+, the solid Co-MOF nanowire were transformed into hollow hierarchical nanowires assembled by nanosheets, allowing for effective modulation of the atomic composition of the titled catalyst. Specifically, this self-supported architecture showcases various advantageous features, including substantial surface areas, elevated structural void porosity, and accessible inner surfaces. These attributes not only facilitate the exposure of abundant active sites but also bolster the structural integrity, consequently facilitating efficient mass diffusion and charge transport. Density functional theory (DFT) calculations revealed that the synergistic effect of Ni, Fe, and Co elements with phosphorus vacancies leads to an increased electron density around the Fermi level, thus optimizing the adsorption free energy of H* and improving its intrinsic catalytic activity. As expected, the optimized catalyst exhibits low overpotentials of 106 and 249 mV for achieving a current density of 10 mA cm–2 in the hydrogen and oxygen evolution reactions, in 1.0 M KOH electrolyte, respectively. Moreover, the electrocatalyst exhibits outstanding bifunctional catalytic activity, achieving a current density of 10 mA cm−2 at a low voltage of 1.62 V in a two-electrode electrolyzer system. These findings demonstrate a potential avenue for the development of efficient and cost-effective bifunctional electrocatalysts for water splitting.

Metal-Doped C3B Monolayer as the Promising Electrocatalyst for Hydrogen/Oxygen Evolution Reaction: A Combined Density Functional Theory and Machine Learning Study.

The development of high-efficiency electrocatalysts for hydrogen evolution reduction (HER)/oxygen evolution reduction (OER) is highly desirable. In particular, metal borides have attracted much attention because of their excellent performances. In this study, we designed a series of metal borides by doping of a transition metal (TM) in a C3B monolayer and further explored their potential applications for HER/OER via density functional theory (DFT) calculations and machine learning (ML) analysis. Our results revealed that the |ΔG*H| values of Fe-, Ag-, Re-, and Ir-doped C3B are approximately 0.00 eV, indicating their excellent HER performances. On the other hand, among all the considered TM atoms, the Ni- and Pt-doped C3B exhibit excellent OER activities with the overpotentials smaller than 0.44 V. Together with their low overpotentials for HER (<0.16 V), we proposed that Ni/C3B and Pt/C3B could be the potential bifunctional electrocatalysts for water splitting. In addition, the ML method was employed to identify the important factors to affect the performance of the TM/C3B electrocatalyst. Interestingly, the results showed that the OER performance is closely related to the inherent properties of TM atoms, i.e., the number of d electrons, electronegativity, atomic radius, and first ionization energy; all these values could be directly obtained without DFT calculations. Our results not only proposed several promising electrocatalysts for HER/OER but also suggested a guidance to design the potential TM-boron (TM-B)-based electrocatalysts.

Bimetallic co-doped CoP nanoflower arrays for efficient and stable overall water splitting

It is vital to develop efficient earth-abundant bifunctional electrocatalysts for water splitting to mitigate the global energy crisis and environmental pollution. Here, Mn and W dual transition metal co-doped CoP nanoflower arrays supported on nickel foam (Mn–W–CoP/NF) have been synthesized via the hydrothermal method and chemical vapor deposition. The unique nanoflower-type structure of Mn–W–CoP/NF facilitated high reactive-site exposure and efficient charge transfer. Consequently, Mn–W–CoP/NF exhibited excellent bifunctional electrocatalytic activity in alkaline electrolytes, with low overpotentials of 95.8 and 229.2 mV for the hydrogen evolution reaction and oxygen evolution reaction, respectively, at 10 mA cm−2. Furthermore, it could be used to construct a two-electrode water-splitting electrolyzer exhibiting stable water splitting at a low cell voltage (1.57 V) at 10 mA cm−2. This study could guide the design and development of efficient bifunctional electrocatalysts for large-scale water-splitting applications.

Synthesis of CuMoS micro‐rods material as efficient bifunctional electrocatalyst for overall water splitting

AbstractIn oxygen evolution reactions (OER) metal sulfides are the subject of extensive research. Copper‐molybdenum sulfides (CuMoS) that can be made a simple hydrothermal treatment are designed to reduce catalyst costs even more. Here, we demonstrate that binder free electrode composed of micro‐rod structure copper‐molybdenum sulfides on nickel foam (CuMoS/NF) can be employed as an active and robust bifunctional electrocatalyst for water splitting. CuMoS/NF catalyst displays an overpotential for OER of 358 mV (121 mV dec−1) and HER of 129 mV (101 mV dec−1) at current density of 10 mA cm−2. CuMoS/NF is stable for 60 hours with potential deviations in OER and HER of 2.8 % and 3.2 %, respectively. The active bifunctional CuMoS/NF electrode combination helps to fabricate a water electrolyser with 10 mA cm−2 current density at 1.65 V. CuMoS/NF//CuMoS/NF shows good stability over 60 hours with a potential deviation of 2.7 %. The earth‘s abundant non‐precious metal‐based electrode, and solar cell delivered continuous hydrogen and oxygen (1.65 V), making it possible to produce a significant quantity of hydrogen at a low‐cost and on a large‐scale.

Encapsulation of cobalt prussian blue analogue-derived ultra-small CoP nanoparticles in electrospun N-doped porous carbon nanofibers as an efficient bifunctional electrocatalyst for water splitting

Transition metal phosphides have been considered as prospective bifunctional electrocatalysts for overall water splitting due to high activity and excellent stability. In this work, we report a facile strategy for synthesizing high-dispersion cobalt Prussian blue analogue-derived CoP nanoparticles that are decorated on N-doped electrospun porous carbon nanofibers (denoted as CoP@CNF). The CoP@CNF is obtained using electrospinning, subsequent carbonization, and phosphatization treatment. Due to the high conductivity, abundance of electrocatalytic active sites, and the synergistic effect between ultra-fine CoP nanoparticles and porous N-doped electrospun carbon nanofibers, the prepared CoP@CNF catalyst exhibits remarkable activity with low overpotentials (127 and 300 mV) at 10 mA cm−2, and small Tafel slopes (73.4 and 73.8 mV dec−1) for hydrogen evolution reaction and oxygen evolution reaction in alkaline electrolyte, respectively. A water electrolyzer cell fabricated by applying CoP@CNF as both anode and cathode catalysts needs 1.64 V to achieve 10 mA cm−2, and exhibits remarkably long-term stability. This work provides useful guidance for the preparation of bifunctional nanocomposite electrocatalysts and further extends the application of Prussian blue analogues in the field of energy conversion.

Strong electronic coupling induced by synergy of dopant and interface in Ru-Ni3S2/NixPy to boost efficient water splitting

It is challenging to fabricate high-efficiency and low-cost bifunctional electrocatalysts for water splitting. Herein, a high-performance nickel-based catalyst, Ru-Ni3S2/NixPy, was constructed via heteroatom doping and interface engineering. The synergy of Ru-doping and sulfide-phosphide heterointerfaces induced the ultrastrong electronic coupling on the catalyst surface, which effectively regulated electronic densities of the catalyst, improved intrinsic catalytic activities, and resulted in the excellent HER and OER bifunctional performances. In alkaline medium, it only required the OER overpotential of 244 mV for the as-prepared Ru-Ni3S2/NixPy catalyst to achieve 100 mA∙cm−2 and the HER overpotential of 51 mV to reach 10 mA∙cm−2. And only a voltage of 1.46 V was required to generate 10 mA∙cm−2 in the Ru-Ni3S2/NixPy(+,-) cell. Furthermore, the as-prepared Ru-Ni3S2/NixPy catalyst exhibited a long-term durability for water splitting. The DFT calculations indicated that the ultrastrong electronic coupling was primarily attributed to the aggregation of electrons around heterointerfaces and the excellent catalytic performance was due to effectively adjusting the adsorption of intermediates on active sites. This work is helpful for developing an effective strategy to fabricate high-performance catalysts.

Active sites engineering construction of spinel cobalt oxide based excellent bifunctional electrocatalyst for water splitting by modifying oxygen vacancy with S dopant

It is a significant and challenging work to endow transition metal oxide highly bifunctional electrocatalytic activities for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Herein, the bifunctional electrocatalysts of S-doped FeCo2O4 ultrafine nanoparticles were fabricated by introducing rich oxygen vacancies (Vo) and then partially substituting the Vo by doping S atoms. The electronic structures and adsorption free energy of the active sites towards reactants were modulated by the strategy of doping sulfur atoms to modify oxygen vacancies. The catalysts were consequently endowed extraordinarily improved HER and OER electrocatalytic activities. The optimized catalyst S-doping FeCo2O4 (FCOS-10) exhibited 33 and 59 times of the turnover frequency as high as that of the pristine FeCo2O4 for HER and OER, respectively. Only 1.54 V of cell voltage for water electrolysis is needed to afford 10 mA cm−2. The catalyst also exhibited robust stability of 85.4% after 120 h i-t test for overall water splitting and high Faraday efficiency of 97.19%, thus it is a high promising catalyst for commercial water electrolysis. This work is one of the few examples that endow metal oxide with highly bifunctional activities for HER and OER, and it is an important reference for rational designing and fabrication of analogous catalysts.

Preparation of Co(OH)2@NiFe/NF bifunctional electrocatalyst by electrodeposition for efficient water splitting

The use of earth-abundant metals such as nickel, iron and cobalt is an effective strategy to develop active bifunctional electrocatalysts for water splitting. Herein, a novel binder-free nickel foam (NF) supported Co(OH)2 composite on NiFe electrocatalyst (denoted as Co(OH)2@NiFe/NF) is developed using simple two-step electrodeposition. The unique structure of Co(OH)2 nanoflowers grown on NiFe nanosheets is observed by SEM. The prepared catalyst has high activity for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The overpotential of HER is 87 mV and that of OER is only 191 mV with current density of 10 mA cm−2 in 1 M KOH. In addition, Co(OH)2@NiFe/NF is used as anode and cathode, which requires only 1.52 V to reach current density of 10 mA cm−2 and 60 h stability, superior to many other advanced electrocatalysts. This provides a new way to prepare low-cost, high-performance and stable electrochemical water electrolysis electrocatalyst.

Quick-to-synthesize hybrid electrodes composed of activated carbon cloth with Co/Fe-based films as bifunctional electrocatalysts for water splitting

Hybrid electrodes have recently been investigated as attractive alternatives to noble-metal-based electrocatalysts for hydrogen production by water splitting. Herein, we propose an electrode composed of an oxidized carbon cloth with an electrodeposited bimetallic Co/Fe-based film. By optimizing the electrodeposition conditions and applying electrochemically activated carbon cloth as a substrate, one can prepare a free-standing noble-metal-free electrocatalytic electrode with high bifunctional electrocatalytic activity in hydrogen and oxygen evolution from alkaline solution. The developed Fe0.25Co0.75 electrode requires overpotentials of 245 mV for HER and 360 mV for OER at high current densities of −100 and 100 mA cm−2, respectively. Furthermore, its overall synthesis time from commercially available raw materials is only approximately 20 min. The electrode material was used as both a cathode and an anode in the model electrolyzer, which can deliver 10 mA cm−2 of current density at 1.66 V without loss of activity during 100 h of performance.

IrPd Nanoalloy-Structured Bifunctional Electrocatalyst for Efficient and pH-Universal Water Splitting.

The lack of high efficiency and pH-universal bifunctional electrocatalysts for water splitting to hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) hinders the large-scale production of green hydrogen. Here, an IrPd electrocatalyst supported on ketjenblack that exhibits outstanding bifunctional performance for both HER and OER at wide pH conditions is presented. The optimized IrPd catalyst exhibits a specific activity of 4.46 and 3.98 A mgIr -1 in the overpotential of 100 and 370mV for HER and OER, respectively, in alkaline conditions. When applied to the anion exchange membrane electrolyzer, the Ir44 Pd56 /KB catalyst shows a stability of >20h at a current of 250mA cm-2 for water decomposition, indicating promising prospects for practical applications. Beyond offering an advanced electrocatalyst, this work also guides the rational design of desirable bifunctional electrocatalysts for HER and OER by regulating the microenvironments and electronic structures of metal catalytic sites for diverse catalysis.

Effects of the cation and anion co-doping in perovskite as bifunctional electrocatalyst for water splitting

Element doping is a very important way to modify perovskite oxide (ABO3) electrocatalyst. Herein, the O, B and A-site of BaCoO3-δ are doped with F, Fe and Sr elements, respectively, which are used to investigate the effect of different doping sites on water splitting performance. The results show that doping F can generate more oxygen vacancies and increase the Co valence state. On the basis of anionic doping, when Co is partially substitute by Fe, the Fe4+ formed makes the O 2P orbital close to EF, and the bandwidth is narrower, enhancing the conductivity. Subsequently, doping Sr in A-site can change the crystal structure from P63/mmc to pm-3m, and exhibit metallic properties. This work can contribute to an effective approach for the design of perovskite oxide materials for efficient electrocatalytic water splitting.

Engineering Cu1.96S/Co9S8 with sulfur vacancy and heterostructure as an efficient bifunctional electrocatalyst for water splitting

Defect and interface engineering have been recognized as efficient strategies for developing high-performance electrocatalysts. However, it is still challenging to couple defect and interface engineering in transition metal sulfides and understand their dynamic evolution process during electrocatalysis. Herein, we developed one-step pyrolysis of bimetallic sulfide to construct S vacancy-rich Cu1.96S/Co9S8 heterostructure by controlling the critical decomposition temperature. The as-synthesized Cu1.96S/Co9S8 exhibits excellent bifunctional electrocatalytic performance, with a low overpotential of 99 and 200 mV at 10 mA cm−2 towards hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in 1.0 mol/L KOH electrolyte, respectively. A symmetric two-electrode cell with Cu1.96S/Co9S8 delivered a current density of 10 mA cm−2 at a low voltage of 1.43 V and showed long-term stability for 200 h. A series of in/ex-situ techniques revealed that the electrochemical reconfiguration only appeared in the OER process, resulting in the CoOOH/CuO and SO42− species promoting OER performance. Meanwhile, the S vacancy and heterostructure interface in Cu1.96S/Co9S8 were proved to optimize the electronic structure and the adsorption of intermediates for HER by density function theory (DFT) simulations. This work provides a promising strategy to construct metal sulfides with rich defects and heterogeneous interfaces and understand their dynamic evolution process for electrochemical storage and conversion devices.