Atomistic insight into the hydration and proton conducting mechanisms of the cobalt doped Ruddlesden-Popper structure Sr3Fe2O7-δ

Sr₃Fe₂O_7-δ (SFO) with two-layer Ruddlesden-Popper (R–P) structure has recently been proved to be a promising material for the single phase cathode in proton conducting solid oxide fuel cells (P–SOFCs). To investigate the hydration reactions and proton conducting mechanisms of SFO and cobalt doped SFO (SFCO), both bulk and surface properties were calculated. We conclude that R–P structures have advantages in P–SOFCs. The unique Sr–O–M layer can facilitate the hydration process. Although in Sr–O–F and Sr–O–N layers, it is difficult for the formation and migration of oxygen vacancies, protons are most stable. Furthermore, cobalt doping can not only improve the electronic conductivity but also enhance surface properties of SFCO. The easily exposed Co–Fe–O surface can also facilitate the hydration reactions on the surface. Our work could give an informative insight into the relationships among the doped elements, the R–P structures, the hydration process and the proton conducting properties.     

Electrochemical activation construction of LaCo1-x-yNixFeyO3 promoted by optimized lattice Ni doping toward water oxidation

Iron sites with high intrinsic activity for oxygen evolution reaction (OER) can effectively enhanced the performance of perovskite oxide as electrocatalyst for water electrolysis. However, doping of iron in perovskite LaCoO₃ remains a challenge owing the strong Co–O bond and robust structure of LaCoO₃. Herein, the lattice doping of Ni in LaCoO₃ has been adopted to promote the interaction between iron ions and Co site in LaCoO₃. Firstly, molten salt of Ni(NO₃)₂ provides free-moving Ni ions to substitute Co sites in the lattice of LaCoO₃ forming LaCo_1-xNi_xO₃ at the optimized Ni doping condition. Then, iron ions can easily be absorbed to LaCo_1-xNi_xO₃ due to the strong interaction between Ni and Fe by electrochemical activation at room temperature. The prepared LaCo_1-x-yNi_xFe_yO₃ nanoparticles keep the coarse surface for maximizing the exposure of active sites. The high-valence Co and oxygen vacancy from LaCo_1-x-yNi_xFe_yO₃ contribute to the better intrinsic activity for OER, demonstrating the overpotential of ?₁₀ of approximately 315 mV and good stability. The strategy of by introducing the lattice doping of other metal ion can realize the facile and effective construction of iron doped perovskite oxide for water oxidation.     

Syngas production by catalytic partial oxidation of methane over (La0.7A0.3)BO3 (A = Ba,Ca, Mg,Sr, and B = Cr or Fe) perovskite oxides for portable fuel cell applications

Hydrogen is a clean energy carrier for the future. More efficient, economic and small-scale syngas production has therefore important implications not only on the future sustainable hydrogen-based economy but also on the distributed energy generation technologies such as fuel cells. In this paper, a new concept for syngas production is presented with the use of redox stable lanthanum chromite and lanthanum ferrite perovskites with A-site doping of Ba, Ca, Mg and Sr as the pure atomic oxygen source for the catalytic partial oxidation of methane. In this process, catalytic partial oxidation reaction of methane occurs with the lattice oxygen of perovskites, forming H₂ and CO syngas. The oxygen vacancies due to the release of lattice oxygen ions are regenerated by passing air over the reduced nonstoichiometric perovskites. Studies by XRD, temperature-programmed reduction (TPR) and activity measurements showed the enhanced effects of alkaline element A-site dopants on reaction activity of both LaCrO₃ and LaFeO₃ oxides. In both series, Sr and Ca doping promotes significantly the activity towards the syngas production most likely due to the significantly increased mobility of the lattice oxygen in perovskite oxide structures. The active oxygen species and performance of the LaACrO₃ and LaAFeO₃ perovskite oxides with respect to the catalytic partial oxidation of methane are discussed.     

N-doped M/CoO (M=Ni,Co, and Mn) hybrid grown on nickel foam as efficient electrocatalyst for the chemical-assisted water electrolysis

In this work, N-Ni₁Co₃Mn_0.4O/NF is synthesized as multifunctional electrocatalyst for hydrogen evolution (HER), urea oxidation reaction (UOR) and hydrazine oxidation reaction (HzOR). The optimal Ni/Co (molar ratio) and the amount of doping Mn are investigated, the sample with Ni/Co = 1:3 and the addition of 0.4 mmol Mn exhibits the best catalytic activity with the largest specific surface area. Then the two-electrode electrolyzers composed of N-Ni₁Co₃Mn_0.4O/NF are constructed, and the results from experiments show that the voltage required for overall hydrazine splitting (OHzS) at 100 mA cm^?2 is 0.272 V, 1.614 V lower than that of overall water splitting (OWS, 1.886 V), while the overall urea splitting (OUS) needs 1.669 V, 0.187 V lower than that of OWS, revealing the outstanding thermodynamic and kinetic advantages of OUS and OHzS. The superior performance may be attributed to the heterostructure between metal and metal oxide and N-doping, which can promote electron transfer and optimizes the decomposition of urea and hydrazine hydrate and hydrogen production, and the research on mechanism will be carried out in the future.     

High-performance bifunctional Fe-doped molybdenum oxide-based electrocatalysts with in situ grown epitaxial heterojunctions for overall water splitting

The design and development of low-cost, abundant reserves, high catalytic activity and durability bifunctional electrocatalysts for water splitting are of great significance. Here, simple hydrothermal and hydrogen reduction methods were used to fabricate a uniform distribution of Fe-doped MoO₂/MoO₃ sheets with abundant oxygen vacancies and heterojunctions on etched nickel foam (ENF). The Fe– MoO₂/MoO₃/ENF exhibited a small overpotential of 36 mV at 10 mA cm⁻² for hydrogen evolution reaction (HER), an excellent oxygen evolution reaction (OER) overpotential of 310 mV at 100 mA cm⁻² and outstanding stabilities of 95 h and 120 h for the HER and OER, respectively. As both cathode and anode catalysts, the heterogeneously structured Fe– MoO₂/MoO₃/ENF required a low cell voltage of 1.57 V at 10 mA cm⁻². Density functional theory (DFT) calculations show that Fe doping and MoO₂/MoO₃ heterojunctions can significantly reduce the band gap of the electrode, accelerate electron transport and reduce the potential barrier for water splitting. This work provides a new approach for designing metal ion doping and heterostructure formation that may be adapted to transition metal oxides for water splitting.     

F-doped CeO2 supported Co-based nanoparticles for enhanced photocatalytic H2 evolution from ammonia borane

Doping as a common mean to generate defects to boost the catalytic performance of metal oxide semiconductor-based materials has aroused great interest. However, doping usually requires high temperatures and is time consuming. Herein, we report a facile strategy for the preparation of F doped CeO₂ (F–CeO₂) with assistance of the electrostatic attraction between F⁻ and CeO₂ with oxygen vacancies at room temperature, then F–CeO₂ acts as superior support of metal Co nanoparticles (NPs) for efficient hydrolysis of NH₃BH₃ under light irradiation. The activity of Co/F–CeO₂ is significantly enhanced and Co/F–CeO₂-0.6 exhibited highest catalytic activity with TOF value 92.8 min⁻¹ which increases 47% compared with Co/CeO₂. Experimental and characterization results show the enhanced performance attributes to high efficiency photogenerated carrier separation and boosting adsorption capacity of H₂O and NH₃BH₃ over Co/F–CeO₂ due to F doped into CeO₂ crystallites. Furthermore, theory calculations further confirm that the band gap of F–CeO₂ becomes smaller and F–CeO₂ is more favorable the adsorption for H₂O and NH₃BH₃ than pure CeO₂. This work offers a facile and time efficiency strategy to realize controllable element doped in metal oxide under ambient, and gives deep insights into the structure–activity relationship of catalyst between defect engineering and photocatalytic performance.     

Phase transition of doped LaFeO3 anode in reducing atmosphere and their power generation property in intermediate temperature solid oxide fuel cell

In general, transition metal-doped La_0.6Sr_0.4FeO₃ (LSF) has been used as a cathode material for intermediate temperature solid oxide fuel cells (IT-SOFCs) because of its high mixed electronic−ionic conductivity and catalytic properties. Recently, some research groups have been investigating the doped LSF as an anode material. In this study, we evaluated the influence of dopant in LSF on anodic properties of LSF in SOFCs. Whereas Mn-doped LSF showed typical perovskite oxide structure even after reduction in hydrogen at high temperature, the LSF and Co-doped LSF exhibited phase transition partially to LaSrFeO₄ and exsolution of metal particles after reduction. The phase transition and metal exsolution occurred at temperature higher than 1008 K in a reducing atmosphere. Despite the partial phase transition, the cell using Co-doped LSF anode exhibited fairly high power density of 1.33 W/cm² at 1173 K with the lowest polarization resistance. These results may originate from the high oxygen-ion conductivity of LaSrFeO₄–La(Sr)Fe(Co)O₃ and the high hydrogen oxidation property of the Co–Fe particles on ceramic anode surface.     

Optimizing strontium titanate anode in solid oxide fuel cells by ytterbium doping

One of advantages of solid oxide fuel cells (SOFCs) is able to utilize various hydrocarbon fuels. Whereas, the classical Ni anode suffers severe carbon deposition especially operated under CH₄. Strontium titanate (SrTiO₃) perovskite anodes with strong carbon deposition resistance and good structural stability have been extensively investigated. In this work, Sr_0.88Y_0.08-xYb_xTiO₃ and Sr_0.88Y_0.08Ti_1-xYb_xO₃ are synthesized by Yb³⁺ doping in A-site and B-site of Sr_0.88Y_0.08TiO₃ perovskite, respectively. XRD results confirm that the SrTiO₃ cubic perovskite phase is formed in all the samples. Among the Yb³⁺ doping samples, Sr_0.88Y_0.06Yb_0.02TiO₃ exhibits the lowest thermal expansion coefficient (11.48 × 10⁻⁶/K), indicating the best compatibility with the electrolyte. The ionic conductivity of Sr_0.88Y_0.08TiO₃ can be improved by proper Yb³⁺ doping both in A-site and B-site, and the Sr_0.88Y_0.06Yb_0.02TiO₃ sample has the highest ionic conductivity among all the samples. The maximum power density of SOFC with Sr_0.88Y_0.06Yb_0.02TiO₃ anode is 87 mW/cm² under CH₄ at 800 °C, which is much higher than that with Sr_0.88Y_0.08TiO₃ and Ni anode. This can be related to its high electrocatalytic activity to CH₄ oxidation. In addition, SOFC with the Sr_0.88Y_0.06Yb_0.02TiO₃ anode shows a superior stability operated under CH₄ due to the strong carbon deposition resistances.     

Perovskite oxides successfully catalyze the electrolytic hydrogen production from oilfield wastewater

Although Pt/C has long been regarded as the most effective HER catalyst, the use of complicated water systems is challenged by high costs and contaminant interference. Therefore, it was shown in this paper that a low-cost perovskite oxide, SrCo_0.7Fe_0.3O_3-δ(SCF-X, where X denotes annealing temperature), could be used in oil-field wastewater to promote electrochemical reactions for hydrogen production and that its catalytic activity can be impacted by calcination temperature. And, the outstanding catalytic activity of SCF-800 and 850 is primarily caused by crystal structure distortions and the presence of Co³⁺/Co⁴⁺ coupling pairs as a result of electron transfer between Co and Fe, which increases the concentration of reactive oxygen species. Furthermore, there is now more interest in SCF-850 due to its exceptional stability. In complicated systems, the current work provides a feasible route for perovskite catalysts to produce hydrogen.     

Enhanced alkaline water splitting on cobalt phosphide sites by 4d metal (Rh)-doping method

The construction of effective water-splitting electrocatalysts in alkaline conditions is challenging due to lower water dissociation efficiency than in acidic conditions. In this study, we investigated the effect of doping 4d and 5d metals into the 3d metal active site of cobalt phosphide (Co_xP) on the water-splitting reaction. Introducing Ru slightly improved hydrogen evolution efficiency, but Rh doping significantly enhanced the catalytic parameters with an overpotential of 0.03 V at 10 mA/cm². Rh regulated the electronic structure of Co_xP to improve proton reduction. The Rh-Co_xP electrode showed a comparable catalytic efficiency to that of a Pt/C standard. Ir doping slightly improved catalytic reactivity, but not as much as Rh. Our results showed that doping 4d metal from the same group as Co maximizes the doping effect during hydrogen evolution. A lab-scale water electrolyzer built with Rh-Co_xP successfully demonstrated catalytic water splitting in alkaline electrolyte.     

Vacancies and phosphorus atoms assembled in amorphous urchin-like Co3O4 for highly efficient overall water splitting

Designing highly efficient and low-cost electrocatalysts is essential for water splitting. Herein, urchin-like Co₃O₄ microspheres are firstly grown on nickel foam by a hydrothermal method, then Oxygen vacancies, phosphorus doping are effectively assembled in Co₃O₄ electrocatalysts. The introduction of oxygen vacancies and phosphorus doping will adjust the electronic structure of Co which increase the intrinsic catalytic activity and improve the adsorption energy of intermediates, simultaneously, progressively transform the crystal into randomly arranged atoms structure with short range order resulting in more active sites participate in the catalytic reaction. Moreover, the catalyst of vacancies Co₃O₄-Ov and phosphorus doping Co₃O₄–P demonstrate excellent performance in oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in alkaline media, Co₃O₄-Ov sample served as anode while Co₃O₄–P as cathode to form an electrolytic cell needs only 1.58 V to reach 20 mA cm^?2 for overall water splitting.     

Self-template synthesis of lychee like Mn-doped Co2P yolk-shell spheres for enhanced hydrogen evolution reaction activity

Designing an electrocatalyst for hydrogen production from water splitting that is highly efficient, stable, and free of noble metals is necessary but challenging. The phosphorus compound is considered a viable candidate for producing hydrogen from water split, but its electrocatalytic performance needs further improvement. Herein, we present an easy and straightforward method for constructing Mn-doped Co₂P yolk-shell lychee spheres. The Co nano prisms are used as a self-sacrificing template to conduct an ion exchange reaction with manganese ions, constructing Co oxide yolk-shell spheres with Mn–Co hydroxide nano-blocks. After in-suit phosphating at low temperature, Mn-doped Co₂P with yolk-shell structure and lychee morphology is formed. The Mn-doped Co₂P with an optimized Mn and Co molar ratio (0.125) exhibits excellent hydrogen evolution performance in alkaline and acidic electrolyte. The overpotentials can reach 10 mA cm^?2 at 98 mV and 72 mV, respectively, and the Mn–Co₂P-0.125 catalyst has faster electron transfer efficiency and larger electrochemically active surface area. The experimental results ascertain that doping an appropriate amount of Mn significantly changes the morphology and structure, thereby affecting the exposure of active sites, and modulating the electronic structure around Co₂P. Under the dual regulation of morphology and electronic structure, the electrocatalytic process is accelerated, enhancing its catalytic activity.     

Renewable syngas & hydrogen synthesis via steam reforming of glycerol over ceria-mediated exsolved metal nano catalysts

Currently, catalyst design and development has drawn much attention as results of its strategic importance in the area of energy applications particular those involving biomass conversion. This work tailored exsolution of metal catalysts through the use of ceria for enhanced structural and catalytic behaviour in steam reforming of glycerol. Aside the understanding that defects due to A-site deficiency facilitates formation of vacant sites and exsolution of metal catalysts on the B-site of perovskite systems, this work has exemplified that metals such as ceria significantly influences the exsolution and general morphological surface architecture and catalytic behaviour. The exsolved nickel catalysts anchored and socketed on a titanate support and the ceria's basic surface properties and oxygen storage-release behaviour has modified the perovskite surface chemistry and enhanced catalytic behaviour particularly deactivation due to carbon deposition and reusability. Other exsolvable dopant metal species such as Fe and Co forms alloys with nickel on the surface and the synergy between the dopant metals in the alloy yielded better results. Furthermore, in one of the catalyst systems, the most commonly observed tolerable A-site deficiency and doping limit of 2% known for SrTiO₃ perovskite was overstretched by 0.5% (2.5%) thereby increasing the defect chemistry. The catalyst system with such formulation has shown a dramatic exsolution phenomenon and catalytic behaviour and robust suppression of coke deposition. CO selectivity >60% and H₂ selectivity >40% was recorded with all the catalyst systems. The catalysts used in this work are useful for applications in energy and production of value added chemicals.     

Effect of angstrom-level oxide overcoat on Sr segregation behavior of LSM electrodes

Long-term durability of perovskite (ABO₃)-based cathodes in solid oxide fuel cells has been largely limited by surface segregation of A-site dopant and thermal agglomeration. Since a deposition of an atomically thin oxide has proven to be highly effective in suppressing electrode agglomeration, a successful suppression of dopant segregation with the same approach will enhance the durability of cathodes significantly by killing two birds with one stone. In this report, we demonstrate that an atomic-scale overcoat with a nominal thickness of 2–3 Å is indeed an effective approach of tuning Sr segregation behavior in La_0.8Sr_0.2MnO₃ (LSM) if a proper choice of the overcoat material is made. Coating of a binary oxide with multi-valent cations (CeO₂ and TiO₂) desegregates Sr species into the lattice of LSM while an overcoat with single valent cations (ZrO₂ and Y₂O₃) exhibits little effect on Sr segregation. A mechanistic interpretation of the behavior is also presented based upon a series of X-ray photoelectron spectroscopy and electrochemical analyses.     

La1-xSrxFeO3 perovskite-type oxides for chemical-looping steam methane reforming: Identification of the surface elements and redox cyclic performance

We report a family of perovskite-type oxides La_1-xSr_xFeO₃ (x = 0.1, 0.3, 0.5, 0.7, 1.0) prepared by combustion method as effective redox catalysts for methane partial oxidation and thermochemical water splitting in a cyclic redox scheme. The effect of Sr-doping on the characterizations and properties of these perovskite-type oxides were studied by means of X-ray diffraction (XRD), hydrogen temperature-programmed reduction (H₂-TPR), X-ray photoelectron spectroscopy (XPS), and scanning electron microscope (SEM). All the as-prepared and regenerated samples with various Sr substitutions exhibited pure crystalline perovskite structure. The oxygen carrying capacity of the La_1-xSr_xFeO₃ perovskites was improved by doping Sr into the La-site. Besides, Sr-substitution has obvious effects on the valences of the Fe cations in the B-site and the oxygen species distribution of the La_1-xSr_xFeO₃ perovskites. We recommend La_0.7Sr_0.3FeO₃ as the optimal oxygen carrier in the series because it gives the maximum O_la/O_ad (O_la and O_ad stand for lattice oxygen and adsorbed oxygen species, respectively.) ratio of 3.64:1, which can be regarded as a criterion for the reactivity and selectivity of partial oxidation of methane into syngas of the oxygen carriers. Up to 80% CH₄ conversion in the methane partial oxidation step and 96% of H₂ concentration in the water splitting step were achieved in ten successive redox tests conducted in a fixed bed reactor at 850 °C with La_0.7Sr_0.3FeO₃ as a redox catalyst. The electronic properties of the original LaFeO₃ cell and its lattice substituted by Sr were calculated based on the density functional theory method. Electronic structure analysis demonstrates that doping of Sr makes LaFeO₃ more electric conductive and its electron is prone to be excited. This is in agreement with the test results that La_0.7Sr_0.3FeO₃ exhibited better performance in chemical looping reactions.     

Nickel and cobalt co-doped MnCO3 nanostructures for water oxidation reaction

Nowadays, electrochemical water splitting is a securing alternative for clean-energy production and also an efficient expertise for oxygen and hydrogen production. Compared to single metal-based electrocatalyst, multi metal-based electrocatalyst offers more active sites, high surface area, and distinctive nanostructure for effective water oxidation. In this work, nickel and cobalt co-doped MnCO₃ was successfully synthesized via a facile co-precipitation technique. Rhombohedral crystal phase of MnCO₃ nanostructures and its crystallite sizes were thoroughly analyzed by the XRD spectra. Incorporation of doping element such as Ni and Co in MnCO₃ nanostructures exhibited two different morphologies which enhanced the catalytic performance of the prepared samples. Large surface area and porosity of the nanomaterials improved the stability and activity of the prepared MnCO₃ nanostructures. EDX analysis confirmed Mn, C, O, Ni and Co elements in stoichometric ratio. Moreover, the specific capacitance of (Ni, Co) co-doped MnCO₃ nanostructures attained 581 F/g while the other electrodes attained only 207, 332 and 175 F/g respectively. A small Tafel slope with low overpotential of Ni, Co co-doped MnCO₃ nanostructures was 20.2 mV/dec and 293 mV respectively. Therefore, the prepared electrocatalysts of Ni, Co co-doped MnCO₃ nanostructure is one of the attractive anode material for high performance energy conversion applications.     

A free-cobalt barium ferrite cathode with improved resistance against CO2 and water vapor for protonic ceramic fuel cells

The triple conducting (electron, oxygen-ion and proton) cathode is promising for protonic ceramic fuel cells (PCFCs). Heavy doping of Fe can impel BaZr_0.9Y_0.1O_3-δ to cross the electronic percolation threshold, forming the triple-conducting BaFe_0.8Zr_0.1Y_0.1O_3-δ (BFZY) material. The partial A-site substitution with La is also designed to further optimize the properties of BFZY. Herein, a systematic study on Ba_0.95La_0.05Fe_0.8Zr_0.1Y_0.1O_3-δ (BLFZY) cathode is conducted for searching potential free-cobalt PCFC cathodes with good tolerance for both CO₂ and water vapor. The XRD result indicates that BLFZY maintains stable cubic perovskite structure. The comprehensive analysis based on XRD, TG and TPD-CO₂ reveals that the BLFZY cathode exhibits an excellent tolerance for CO₂ and water vapor. The La doping also has a positive influence on the thermal expansion coefficient, electrical conductivity, and electrocatalytic activity. The anode-supported single cell with single-phase BLFZY cathode achieves a peak power density of 305 mW cm^?2 and polarization resistance of 0.492 Ω cm² at 600 °C and maintains steady power output in the short-term durability test. This indicates that the BLFZY material is a good cathode candidate for PCFCs.     

Phase transition in V-doped cobalt hydroxide for efficient oxygen evolution and urea oxidation reaction

In this work, many kinds of V doped Co(OH)₂ electrodes were in situ synthesized on Ni foam by a one-step typical hydrothermal process. It is worth noting that the phase transition composition of the V doped Co(OH)₂ material can be modulated by the difference of the amount of the V introduced. Different crystal phase compositions show different water oxidation activities. It is worth noting that the V2–Co(OH)₂/NF electrode shows better oxygen evolution performance (Overpotential of 320 mV@50 mA cm⁻²) compared with Co(OH)₂/NF (450 mV@50 mA cm⁻²), V1–Co(OH)₂/NF (340 mV@50 mA cm⁻²) and V3–Co(OH)₂/NF (350 mV@50 mA cm⁻²) electrodes. The experimental results show that not all doping can improve the electrochemistry performance of electrodes, such as the oxidation of urea. Density functional theory calculation further proves that the doping of the V is favorable to the adsorption of water and inhibits the adsorption of urea. This study provides a new idea for the development of efficient overall water splitting catalysts.     

Evidencing enhanced oxygen and hydrogen evolution reactions using In–Zn–Co ternary transition metal oxide nanostructures: A novel bifunctional electrocatalyst

Ternary transition metal oxides are gaining popularity for cost effective bifunctional electrocatalytic activities and to realization of novel water splitting devices. In this regard, In₂O₃/ZnO/Co₃O₄ based ternary oxide nanostructures were investigated in detail for their oxygen/hydrogen evolution reaction (OER/HER) in alkaline environment. The ternary oxides were at first processed through a simple chemical route involving hydrothermal treatment. The prepared nanostructures were then investigated by using high-resolution transmission electron microscopy (TEM/HRTEM) to ascertain their morphological traits. X-ray diffraction, Raman signals and photoluminescence data demonstrated the In₂O₃ phase to be prevalent in the ternary mixture on par with that of ZnO and Co₃O₄. The valence state of various metal ions and the In–O, Zn–O and Co–O bonding was verified using XPS. The ternary oxide coated electrodes exhibited excellent overall water splitting activity. Overpotential values of 398 and 510 mV were registered for OER and HER experiments under a current density of ±10 mA cm⁻², demonstrating the material to be an ideal OER/HER electrocatalyst at room temperature. The exceptional long-term stability in ternary oxides and their Tafel slope (88 mV/dec for OER and 60 mV/dec for HER) further affirmed their unique anodic/cathodic characteristics for water splitting applications.     

Structure-design and synthesis of nickel-cobalt oxide/sulfide/phosphide composite nanowire arrays for efficient overall water splitting

The construction of cost-effective bifunctional electrocatalysts with the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is significant for efficient overall water splitting. Herein, this work demonstrates a novel strategy for the synthesis of nickel-cobalt oxides/sulfides/phosphides composite (denoted as NiCoO–2P/S) nanoarrays on Ni foam. In this method, Ni–Co bimetallic oxide nanowires on Ni foam were partially phosphorized and sulfurized simultaneously in situ to yield Ni–Co oxide/sulfide/phosphide composite. The NiCoO–2P/S arrays have good interfacial effects and display many holes in the nanowires, giving it the advantage of large accessible surfaces on the nanowires and a beneficial for the release of gas bubbles, resulting in an excellent OER performance with a low overpotential (η) of 254 mV at 100 mA cm^?2 and good HER activity (η₁₀ = 143 mV at 10 mA cm^?2). The electrocatalytic test results demonstrate small Tafel slopes (82 mV dec^?1 for HER, 88 mV dec^?1 for OER) and the satisfying durability in an alkaline electrolyte, indicating that the HER and OER activity was enhanced by the introduction of the Ni/Co sulfides and phosphides into Ni–Co oxides composite nanowires. Furthermore, the as-prepared NiCoO–2P/S catalyst can be used as both the anode and the cathode simultaneously to realize overall water splitting in the two-electrode electrolyzer. This system can be driven at low cell voltages of 1.50 and 1.68 V to achieve current densities of 10 and 100 mA cm^?2, respectively. This work provides an alternative strategy to prepare high-performance bifunctional electrochemical materials and demonstrates the advantages of Ni–Co oxide/sulfide/phosphide composites for water splitting.