Flower-shaped and sea urchin-shaped structures coexisting in cobalt-based phosphate and oxides achieve efficient electrochemical overall water electrolysis

Active site engineering for electrocatalysts is an essential strategy to improve their intrinsic electrocatalytic capability for practical applications and it is of great significance to develop a new excellent electrocatalyst for overall water splitting. Here, Co₃O₄/nickel foam (NF) and Co₂(P₄O₁₂)/NF electrocatalysts with flower-shaped and sea urchin-shaped structures are synthesized by a simple hydrothermal process and followed by a post-treatment method. Among them, Co₂(P₄O₁₂)/NF shows good catalytic activity for hydrogen evolution reaction (HER), and at the current density of 10 mA cm^?2, the overpotential is only 113 mV Co₃O₄/NF exhibits good catalytic activity for oxygen evolution reaction (OER), and the overpotential is 327 mV at 20 mA cm^?2. An alkaline electrolyzer with Co₃O₄/NF and Co₂(P₄O₁₂)/NF catalysts respectively as anode and cathode displays a current density of 10 mA cm^?2 at a cell voltage of 1.59 V. This work provides a simple way to prepare high efficient, low cost and rich in content promising electrocatalysts for overall water splitting.     

3D V–Ni3S2@CoFe-LDH core-shell electrocatalysts for efficient water oxidation

Studying cheap and efficient electrocatalysts is of great significance to promote the sluggish kinetics of oxygen evolution reaction (OER). Here, we adopted a simple two-step method to successfully prepare the 3D V–Ni₃S₂@CoFe-LDH core-shell electrocatalyst. The V–Ni₃S₂@CoFe-LDH/NF shows excellent OER performance with low overpotential (190 mV at 10 mA/cm² and 240 mV at 50 mA/cm²), small Tafel slope (26.8 mV/dec) and good long-term durability. Excitingly, to reach the same current density, V–Ni₃S₂@CoFe-LDH/NF electrode even needs much smaller overpotential than RuO₂. Furthermore, the outstanding OER activity of V–Ni₃S₂@CoFe-LDH/NF is ascribed to the following reasons: (1) V–Ni₃S₂ nanorod cores improve the conductivity and ensure the fast charge transfer; (2) CoFe-LDH nanosheets interconnected with each other provide more exposed active sites; (3) the unique 3D core-shell structures are favorable for electrolyte diffusion and gas releasing. Our work indicates that building 3D core-shell heterostructure will be a useful way to design good electrocatalysts.     

Oxygen vacancy-based ultrathin Co3O4 nanosheets as a high-efficiency electrocatalyst for oxygen evolution reaction

Enhancing the catalytic activity of Co₃O₄ electrocatalysts featuring abundant oxygen vacancies is required to enable their application in oxygen evolution reaction (OER). However, developing a harmless defect engineering strategy based on mild conditions to realize such an enhancement remains a challenge. Here, ultrathin Co₃O₄ nanosheets with abundant oxygen vacancies were prepared through a simple two-step method comprising a hydrothermal process and pre-oxidation to study the catalytic activity of the nanosheets toward OER. The ultrathin sheet structure and the Co₃O₄ nanosheets surface provide abundant active sites. The oxygen vacancy not only improves the catalyst activity, but also improves the electron transfer efficiency. These advantages make ultrathin Co₃O₄ nanosheets with abundant oxygen vacancies an excellent electrocatalyst for oxygen evolution. In an alkaline medium, ultrathin Co₃O₄ nanosheets exhibited excellent OER catalytic activity, with a small overpotential (367 mV for 10 mA/cm²) and faster reaction kinetics (65 mV/dec).Moreover, the electrocatalyst still maintained 68% of its original catalytic activity after 24 h operation. This work provides an extensive and reliable method for the preparation of low-cost and highly efficient OER electrocatalysts.     

An efficient and durable bifunctional electrocatalyst based on PdO and Co2FeO4 for HER and OER

The adoption of effective, minimal, and versatile electrocatalysts for water splitting to generate hydrogen fuels is of critical importance. The bulk of newly described materials have considerable onset potential, but their electrocatalytic activity is limited by weak electrical conductivity and a limited range of catalytic sites. The combination of a few precious metals added with transition metal-based compounds is a novel and captivating approach. Herein, cobalt ferrite oxide (Co₂FeO₄) @ palladium oxide (PdO) nanostructures have been prepared through the combined use of hydrothermal and ultraviolet (UV) irradiation techniques. For hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) kinetics, the modified composition offers a high concentration of active sites, improved electrical conductivity, and stability. The Co, Fe, and Pd ions at the composite system's interface may affect the adsorption energy of reaction intermediates synergistically, enabling the process to continue with less potential. The electrocatalyst Co₂FeO₄@PdO demonstrates an excellent bifunctional approach to electrochemical water splitting (EWS) for HER and OER in alkaline medium. As-prepared electrocatalyst shows an overpotential value of 269 and 259 mV for HER and OER at 10 and 20 mA/cm² current densities respectively. The low charge transfer resistance values such as 72.2 and 62.4 Ω and durability for 48 h has been observed toward HER and OER, support this material as an efficient and durable electrocatalyst for energy conversion systems.     

Three-dimensional ZnCo/MoS2–Co3S4/NF heterostructure supported on nickel foam as highly efficient catalyst for hydrogen evolution reaction

Exploring inexpensive and earth-abundant electrocatalysts for hydrogen evolution reactions is crucial in electrochemical sustainable chemistry field. In this work, a high-efficiency and inexpensive non-noble metal catalysts as alternatives to hydrogen evolution reaction (HER) was designed by one-step hydrothermal and two-step electrodeposition method. The as-prepared catalyst is composed of the synergistic MoS₂–Co₃S₄ layer decorated by ZnCo layered double hydroxides (ZnCo-LDH), which forms a multi-layer heterostructure (ZnCo/MoS₂–Co₃S₄/NF). The synthesized ZnCo/MoS₂–Co₃S₄/NF exhibits a small overpotential of 31 mV and a low Tafel plot of 53.13 mV dec^?1 at a current density of 10 mA cm^?2, which is close to the HER performance of the overpotential (26 mV) of Pt/C/NF. The synthesized ZnCo/MoS₂–Co₃S₄/NF also has good stability in alkaline solution. The excellent electrochemical performance of ZnCo/MoS₂–Co₃S₄/NF electrode originates from its abundant active sites and good electronic conductivity brought by the multilayer heterostructure. This work provides a simple and feasible way to design alkaline HER electrocatalysts by growing heterostructures on macroscopic substrates.     

Co3O4 nanosheet arrays treated by defect engineering for enhanced electrocatalytic water oxidation

Due to its poor electrical conductivity and finite exposed active sites, the development of high activity Co₃O₄ oxygen evolution reaction (OER) electrocatalysts remains a major challenge. Oxygen vacancies can enhance the electrical conductivity of electrocatalysts and reduce the adsorption energy of H₂O molecules on surfaces, thereby significantly enhancing their electrocatalytic activity. Taking inspiration from this, we demonstrate a green and facile reduction strategy to prepare reduced Co₃O₄ nanosheet arrays (R-Co₃O₄ NSA) with large electrochemical surface area and rich in surface oxygen vacancies. Compared to pristine Co₃O₄ nanosheet arrays (P-Co₃O₄ NSA), R-Co₃O₄ NSA exhibits better OER performance, with a lower overpotential of 330 mV at a current density of 20 mA cm^?2 and a smaller Tafel slope of 72 mV dec^?1. Impressively, the excellent properties of R-Co₃O₄ NSA can rival to the state-of-the-art noble metal oxide electrocatalyst (IrO₂). This strategy of defect-engineering offers a briefness and cost-effective means for the development of highly efficient OER systems.     

Iron-substituted Co-Ni phosphides immobilized on Ni foam as efficient self-supported 3D hierarchical electrocatalysts for oxygen evolution reaction

Electrocatalytic water splitting for hydrogen evolution is significantly impeded by the kinetically sluggish oxygen evolution reaction (OER). Thus, the development of highly efficient and durably stable non-noble-metal OER electrocatalyst is necessary and challenging for the large-scale electrocatalytic water splitting. Herein, a series of iron-substituted cobalt-nickel phosphides grown on Ni foam (FeCoNi-P/NFs) were easily prepared though successive hydrothermal and phosphorization treatments. The chemical compositions, crystalline and electronic structures as well as surface morphologies of these resulting electrocatalysts are strongly related with the iron substitution ratio. More interestingly, the FeCoNi-P/NF-2 nanosheet arrays prepared from equivalent molar ratio of iron and cobalt precursors exhibit the best OER performance with a low overpotential of 266 mV to produce a current density of 50 mA cm⁻² and a low Tafel slope of 61.2 mV dec⁻¹ in 1.0 M KOH condition, which is comparable to the reported state-of-the-art OER electrocatalysts. Additionally, the FeCoNi-P/NF-2 nanosheet arrays also show satisfactory long-term durability over 60 h. The superior OER activity of the electrocatalyst is essentially attributed to the heteroatomic substitution and the unique three-dimensional hierarchical morphology, which greatly increase the electrical conductivity, afford more active sites and facilitate the efficient charge transfer ability.     

Surface engineering of 2D MOF to construct high-density Co9S8 nanoparticles supported on nitrogen doped carbon for efficient oxygen evolution reaction

Transition metal sulfides and their hybrids are promising alternative to precious metal catalyst for the oxygen evolution reaction (OER). Herein, the high-density Co₉S₈ nanoparticles (NPs) embedded in N-doped carbon has been prepared by using surface-engineered zeolitic imidazolate framework-9 (ZIF-9) nanosheets as precursor. The surface of ZIF-9 was modified with TAA, which is able to create chemical barrier and prevents metal from aggregation in the subsequent pyrolysis, thus making small Co₉S₈ NPs densely anchored on carbon layers. Arising from the unique structure, Co₉S₈@NC affords an optimized electronic structure and rich effective reactive sites for OER. As expected, Co₉S₈@NC exhibits small overpotential of 264 mV at 10 mA cm⁻², low Tafel slope of 68.4 mV dec⁻¹, and superior stability for alkaline OER (0.1 M KOH). The electrolysis cell, which was equipped with Co₉S₈@NC cathode and Pt/C anode, shows low water splitting voltage of 1.58 V at 10 mA cm⁻² in 1.0 M KOH. This work employs an efficacious surface engineering strategy to design metal sulfide-based electrocatalysts for enhancing OER performance.     

Hierarchical Ni/Co-hydroxides on NiCo2O4 for boosting the electrocatalytic activity of the oxygen evolution reaction

Herein, hierarchical Ni/Co-layered double hydroxide decorated NiCo₂O₄ electrocatalyst (NiCo-LDH@NCO) on nickel foam (NF) was synthesized using a facile hydrothermal method with electrochemical reconstruction. By converting the already existing NCO surface to hierarchical NiCo-LDH, a larger surface area and high electrical conductivity are obtained. Both structure and morphology of fabricated electrocatalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and field emission scanning electron microscopy (FESEM) techniques. The electrochemical reconstruction process is accompanied by changes in the morphology of the NCO that significantly increase accessibility to the electrolyte and active surface area. Therefore, the as-obtained electrocatalyst exhibits excellent oxygen evolution reaction (OER) activity and long-term stability for 35 h continuous reaction, superior-performing the reported other OER catalysts. In addition, this work opens a new path for the development of highly efficient and innovative low-cost OER electrocatalysts able to replace Pt-based metals for energy conversion devices.     

Ga doped Ni3S2 ultrathin nanosheet arrays supported on Ti3C2-MXene/Ni foam: An efficient and stable 3D electrocatalyst for oxygen evolution reaction

Exploring cost-efficient electrocatalysts for oxygen evolution reaction (OER) is still a huge challenge in the electrochemical energy conversion technology. In this work, Gallium (Ga)-doped Ni₃S₂ nanosheet arrays grown on Ti₃C₂-MXene/nickel foam (Ga–Ni₃S₂/Ti₃C₂/NF) have been synthesized by a successive hydrothermal and sulfidization process. The Ga doping modulates the electronic structure of Ni₃S₂, so tuning the adsorption energies of oxygen intermediate (1OOH). The Ga–Ni₃S₂/Ti₃C₂/NF delivers outstanding catalytic activities toward OER with an overpotential of 340 mV at 100 mA cm^?2, and exhibits superior electrochemical durability. The excellent OER performance of Ga–Ni₃S₂/Ti₃C₂/NF can be ascribed to the 3D sheet arrays morphology and optimized electronic structure. Density functional theory (DFT) calculations also demonstrate that electronic disturbance attributed to Ga doping effectively improves the activity of Ni sites, leading to stronger binding strength of 1OOH intermediate at Ni sites nearby Ga. This study provides insights into the fabrication of advanced electrocatalysts for application.     

Se-doped cobalt oxide nanoparticle as highly-efficient electrocatalyst for oxygen evolution reaction

Electrolysis of water has been one of the most promising approaches for renewable energy resources while the efficient oxygen evolution reaction (OER) remains challenging. Herein, a series of different ratio of Se doped Co₃O₄ nanoparticles XSe-Co₃O₄ are prepared by hydrothermal method and applied as OER electrocatalysts. Se^2? is doped into the Co₃O₄ crystal lattice by substituting of O^2? and a large number of oxygen vacancies are generated, which provides more available activity sites for OER. Se doping increases the surface ratio of Co²⁺/Co³⁺ and accelerates the electron transport that favors OER activity promotion. The optimized doping ratio of 6%Se–Co₃O₄ presents low overpotential of 281 mV at 10 mA cm^?2, as well as a low Tafel slope of 70 mV dec^?1 in 1 M KOH solution, which has great advantages compared to the recently reported Co₃O₄-based OER electrocatalysts. This work provides new ideas for the development of efficient Co₃O₄-based OER electrocatalysts.     

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.     

ZIF-67-derived Mn doped Co9S8 supported on N-Enriched porous carbon polyhedron as an efficient electrocatalyst for oxygen evolution reaction

Rational design of efficient oxygen evolution reaction (OER) electrocatalysts plays a significant role in various applications like water splitting and metal-air batteries. Simultaneous modulation of geometric and electronic structure is a promising strategy for boosting the electrocatalytic active of OER catalysts. Herein, a novel type of Mn doped Co₉S₈ supported on N-enriched porous carbon polyhedron composite material (Mn–Co₉S₈/NC) is constructed via absorption-pyrolysis-sulfurization treatment of Zeolitic-imidazolate frameworks (ZIF-67). ZIF-67 derived N-enriched porous carbon polyhedron serves as the porous skeleton for anchoring numerous Co₉S₈ nanoparticles. The results confirm that the incorporation of Mn in Co₉S₈/NC can improve the degree of graphitization compared with Co₉S₈/NC, implying the enhancement of the conductivity. Meanwhile, the incorporation of Mn can lead to electronic modulation of Co species to bump up the intrinsic activity of active site in Mn–Co₉S₈/NC. Due to the synergistic effect of Mn, Co₉S₈ and porous carbon structure, the specific surface area and electronic structure are optimized, endowing the maximum utilization of active sites. The Mn–Co₉S₈/NC electrocatalyst exhibits superior OER activity with the overpotential of 286 mV at current density of 10 mA cm⁻² in 1.0 M KOH electrolyte. This work provides prospective insights into the synergistic coupling of geometric and electronic structure of Metal-Organic Frameworks (MOFs) material for efficient electrocatalysts.     

Facile one-pot synthesis of binder-free nano/micro structured dendritic cobalt activated nickel sulfide: a highly efficient electrocatalyst for oxygen evolution reaction

Reasonable design and preparation of non-noble metal electrocatalysts with predominant catalytic activity and long-term stability for oxygen evolution reaction (OER) are essential for electrocatalytic water splitting. Ni foam (NF) is highlighted for its 3D porous structure, impressive conductivity and large specific surface area. Herein, nano/micro structured dendritic cobalt activated nickel sulfide grown on 3D porous NF (Co–Ni₃S₂/NF) has been successfully synthesized by one-step hydrothermal method. Due to the ingenious incorporation of Co, Co–Ni₃S₂/NF electrode shows auspicious electrocatalytic performance for OER compared with Ni₃S₂/NF electrode. As a result, Co–Ni₃S₂/NF needs overpotential of only 274 and 459 mV at current density of 10 and 50 mA cm⁻², respectively, while Ni₃S₂/NF requires overpotential of 344 and 511 mV. At potential of 2.0 V (vs. RHE), Co–Ni₃S₂/NF displays current density of 191 mA cm⁻², while Ni₃S₂/NF just attains current density of only 135 mA cm⁻². Moreover, Co–Ni₃S₂/NF demonstrates excellent stability for uninterrupted OER in alkaline electrolyte. The strategy of designing and preparing cobalt activated nickel sulfide grown on NF renders a magnificent prospect for the development of metal-sulfide-based oxygen evolution catalysts with excellent electrocatalytic performances.     

Co0.85Se on three-dimensional hierarchical porous graphene-like carbon for highly effective oxygen evolution reaction

Designing an efficient, cheap and abundant catalyst for oxygen evolution reaction (OER) is crucial for the development of sustainable energy sources. A novel catalyst which could be a promising candidate for such electrocatalysts is described. Co_0.85Se supported on three-dimensional hierarchical porous graphene-like carbon (HPG) exhibits outstanding catalytic performances for OER in alkaline medium. It is found that the onset overpotential is 311 mV on the Co_0.85Se/HPG electrode, which is more 28 and 41 mV negative than that on the Co/HPG and Co₃O₄/HPG electrodes. What's more, the value of Tafel slope is 61.7 mV dec⁻¹ and the overpotential at the current density of 10 mA cm⁻² is 385 mV on this electrode. The Co_0.85Se/HPG of this work is an appealing electrocatalyst for OER in basic electrolyte.     

Reduced graphene oxide composite Ni3S2 microspheres grown directly on nickel foam as an efficient electrocatalyst for OER

The development of cheap, high-efficiency, and stable oxygen evolution reaction (OER) electrocatalysts is a current research hotspot. In this work, reduced graphene oxide (rGO) composite Ni₃S₂ microspheres grown directly on nickel foam (Ni₃S₂-rGO/NF) were prepared by tube furnace calcination and hydrothermal method. The Ni₃S₂-rGO/NF had excellent OER catalytic activity and stability with an overpotential of 303 mV at the current density of 100 mA cm⁻², which was 100 mV lower than that of Ni₃S₂/NF, and its Tafel slope was as low as 23 mV·dec⁻¹. The main reason for enhancing OER activity of the Ni₃S₂-rGO/NF is due to synergistic effect of Ni₃S₂ microspheres and rGO, which inhibited the production of NiS and refined the micron size of Ni₃S₂. This work offers a new method for developing stable and efficient OER catalysts.     

Facile synthesis of binary NiCoS nanorods supported on nickel foam as efficient electrocatalysts for oxygen evolution reaction

A facile two-step method has been applied to synthesize novel binary metal NiCoS nanorods supported on nickel foam (NF) as electrocatalysts for oxygen evolution reaction (OER). Firstly, electrodeposition process is conducted to fabricate binary Ni-Co hydroxides on NF (NiCo/NF). Then, a hydrothermal sulfuration of NiCo/NF has been adopted to prepare NiCoS nanorods arrays uniformly grown on the surface of NF (NiCoS/NF). XRD indicates that NiCoS/NF has mixed crystal phases of Ni₃S₂, CoS and Co₉S₈. SEM images display the uniform NiCoS nanorods composed of many vertical nanosheets on the surface, implying more exposed active sites. OER measurements demonstrate that NiCoS/NF has better activity with an overpotential of 370 mV to reach 100 mA cm^?2 than NiCo/NF and CoS_x/NF. Electrochemical impedance spectroscopy (EIS) tests confirm the faster charge-transfer rate of NiCoS/NF and smaller Tafel slope derived from binary NiCoS, implying the excellent electrocatalytic performances of binary metal sulfides.     

Ir-doped Co3O4 as efficient electrocatalyst for acidic oxygen evolution reaction

Oxygen evolution reaction (OER) is an important bottleneck for large-scale acidic water splitting applications due to its sluggish reaction kinetics. Therefore, the development of highly active, stable, and inexpensive electrocatalysts for OER remains a challenge. Herein, we develop the iridium doped Co₃O₄ (Ir–Co₃O₄) with low Ir content of 2.88 wt% for efficient acidic OER. Considering systemic characterizations, it is probably concluded that Ir can be uniformly doped into the lattice of Co₃O₄ and induce a certain distortion. The electrochemical results reveal that Ir–Co₃O₄ nanoparticles demonstrate significantly enhanced electrocatalytic OER activity and stability in 0.5 M H₂SO₄ solution compared with pure Co₃O₄, in which the overpotential at the current density of 10 mA cm⁻² decreases from 382 mV to 225 mV and the value of Tafel slope decreases from 101.7 mV dec⁻¹ to 64.1 mV dec⁻¹. Besides, Ir–Co₃O₄ exhibits excellent electrocatalytic durability for continuous 130 h's test without any activity attenuation. Moreover, this work provides a kind of high-performance acidic OER electrocatalyst for the development of hydrogen energy.     

Amorphous CoFeP/NC hybrids as highly efficient electrocatalysts for water oxidation

The rational design and regulate structure and composition are pivotal for the development of highly efficient oxygen evolution reaction (OER) catalysts for water splitting. In this study, amorphous CoFeP/NC hybrid electrocatalyst has been synthesized by a simple and effective phosphorization of a CoFe-based coordination polymer under N₂ atmosphere. The synergistic effects between the CoFeP and N-doped carbon has led to high electronic conductivity attributed to the optimal Fe contents with N-doped carbon and enlarged electrocatalytic active surface area aroused by the nanostructure of CoFeP/NC, as well as the surface structural evolution of oxyhydroxide/phosphate during OER process. The resulting Co_0.35Fe_0.17P_0.48/NC electrocatalyst can attain a current density of 10 mA/cm² at an overpotential of 275 mV with a Tafel slope of 31 mV/dec on glassy carbon electrode and 228 mV on Ni foam electrode in 1 M KOH solution, long-term OER stability of this Co_0.35Fe_0.17P_0.48/NC under the applied potential of 1.53 V vs. RHE demonstrates no obvious decline in current densities of 110 mA/cm² within 17 h, which outperforms those of the contrast electrocatalysts in this work and also comparable to that of many of the reported electrocatalysts in the literatures. This Co_0.35Fe_0.17P_0.48/NC electrocatalyst highlights the rational modulation of optimal composition and electronic structure with homogeneous incorporation of the foreign metal-doped and N-doped carbon for the synthesis of highly efficient electrocatalysts toward to the water oxidation reactions.     

Synergistic coupling of CoFe-layered double hydroxide nanosheet arrays with reduced graphene oxide modified Ni foam for highly efficient oxygen evolution reaction and hydrogen evolution reaction

Novel CoFe-LDH (layered double hydroxide) nanosheet arrays in situ grown on rGO (reduced graphene oxide) uniformly modified Ni foam were synthesized by a citric acid-assisted aqueous phase coprecipitation strategy. Systematic characterizations indicates that the series of Co_xFe₁-LDH/rGO/NF (x = 4, 3, 2) all show Co_xFe₁-LDH nanosheets (150–180 × 15 nm) grown vertically on the surface of rGO/NF. Especially, the Co₃Fe₁-LDH/rGO/NF exhibits the best performance with overpotentials of 250 and 110 mV at 10 mA cm^?2 in 1 M KOH for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), respectively. When it is used as cathode and anode simultaneously for overall water splitting, they require 1.65 and 1.84 V at 10 and 100 mA cm^?2, respectively. Excellent performance of Co₃Fe₁-LDH/rGO/NF is due to the nanosheet arrays structure with open channels, synergistic coupling between Co₃Fe₁-LDH and rGO enhancing electrical conductivity, and in-situ growth of Co₃Fe₁-LDH on rGO/NF enhancing stability.