Cu2S/Ni3S2 ultrathin nanosheets on Ni foam as a highly efficient electrocatalyst for oxygen evolution reaction

It is an inevitable choice to find efficient and economically-friendly electrocatalysts to reduce the high overpotential of oxygen evolution reaction (OER), which is the key to improve the energy conversion efficiency of water splitting. Herein, we synthesized Cu₂S/Ni₃S₂ catalysts on nickel foam (NF) with different molar ratios of Ni/Cu by a simple two-step hydrothermal method. Cu₂S/Ni₃S₂-0.5@NF (CS/NS-0.5@NF) effectively reduces the overpotential of OER, displaying small overpotentials (237 mV@100 mA cm^?2 and 280 mV@500 mA cm^?2) in an alkaline solution, along with a low Tafel slope of 44 mV dec^?1. CS/NS-0.5@NF also presents an excellent durability at a relatively high current density of 100 mA cm^?2 for 100 h. The excellent performance is benefited by the prominent structural advantages and desirable compositions. The nanosheet has a high electrochemical active surface area and the porous structure is conducive to electrolyte penetration and product release. This work provides an economically-friendly Cu-based sulfide catalyst for effective electrosynthesis of OER.     

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.     

Reduced CoFe2O4/graphene composite with rich oxygen vacancies as a high efficient electrocatalyst for oxygen evolution reaction

Oxygen evolution reaction (OER) is regarded as a limit-efficiency process in electrochemical water splitting generally, which needs to develop the effective and low-cost non-noble metal electrocatalysts. Oxygen vacancies have been verified to be beneficial to enhance the electrocatalytic performance of catalysts. Herein, we report the facile synthesis of reduced CoFe₂O₄/graphene (r-CFO/rGO) composite with rich oxygen vacancies by a citric acid assisted sol-gel method, heat treatment process and the sodium borohydride (NaBH₄) reduction. The introduction of graphene and freezing dry technique prevents the restacking of GO and the aggregation of CFO nanoparticles (NPs) and increases the electronic conductivity of the catalyst. Fast heating rate and low anneal temperature favors to obtain low crystallinity and lattice defects for CFO. NaBH₄ reduction treatment further creates the rich oxygen vacancies and electrocatalytic active sites. The obtained r-CFO/rGO with high specific surface area (108 m² g⁻¹), low crystallinity and rich oxygen vacancies demonstrates a superior electrocatalytic activity with the smaller Tafel slope (68 mV dec⁻¹), lower overpotential (300 mV) at the current density of 10 mA cm⁻², and higher durability compared with the commercial RuO₂ catalyst. This green, low-cost method can be extended to fabricate similar composites with rich defects for wide applications.     

Flower-like Co3O4 microstrips embedded in Co foam as a binder-free electrocatalyst for oxygen evolution reaction

Designing appropriate oxygen evolution reaction (OER) electrocatalysts to meet the requirements of high efficiency, long-term durability, and low cost remains the challenge for scientific community. Cobalt oxide (Co₃O₄) has been proven as a promising candidate for OER with attractive activity and stability in alkaline media. In this study, flower-like Co₃O₄ microstrips have been successfully prepared and directly embedded in Co foam (denoted as Co₃O₄@Co foam) by a green and facile two-step strategy including hydrothermal treatment and subsequent annealing process under relatively low temperatures. It demonstrates that the OER performance of the Co₃O₄@Co foam electrode can rival to the commercial RuO₂ on glassy carbon electrode. The Co₃O₄@Co foam electrode displays high OER activity with a low overpotential of 273 mV at a current density of 10 mA cm⁻², and a low Tafel slope of 61.8 mV dec⁻¹. The flower-like Co₃O₄ microstrips greatly increase the active surface area to expose more active sites, and the directly growth of Co₃O₄ microstrips on Co foam with intimate contact improves the electron transport and ensures the stability of the Co₃O₄@Co foam electrode.     

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.     

Development of NiO/Co3O4 nanohybrids catalyst with oxygen vacancy for oxygen evolution reaction enhancement in alkaline solution

The oxygen evolution reaction (OER) is a significant reaction in water splitting and energy conversion. However, high price and sluggish kinetics catalysts prevent commercial applications. Generally, noble metals (e.g., iridium and ruthenium), which are expensive and unstable, have been used as catalysts for OER because of their high electrocatalytic activity. In this study, we report a high-performance OER catalyst with oxygen vacancies comprising NiO/Co₃O₄ nanohybrids. For OER, the NiO/Co₃O₄ heterostructure show good electrocatalytic performance with a low overpotential of 330 mV. This is higher than those of NiO, Co₃O₄, and benchmark IrO₂ candidates at current density of 10 mA cm^?2. Furthermore, the NiO/Co₃O₄ nanohybrids show long-term electrochemical stability for 10 h. The present research results show that NiO/Co₃O₄ heterostructure is an excellent electrocatalyst for OER.     

A facile method for reduced CoFe2O4 nanosheets with rich oxygen vacancies for efficient oxygen evolution reaction

The efficiency of electrochemical water splitting is greatly hindered by the thermodynamic uphill reaction of oxygen evolution reaction (OER). Thus, it is important to synthesize an active OER electrocatalysts with abundant active sites, favorable conductivity and good durability. Herein, a facile reduction method using NaBH₄ as readily available reductant has been developed to fabricate the reduced CoFe₂O₄ nanosheets (NS). The obtained reduced CoFe₂O₄ NS are rich in oxygen deficient sites, leading to more active sites as well as the enhanced conductivity than the pristine CoFe₂O₄ hollow nanosphere, which reaches the current density of 10 mA cm^?2 at the overpotential of 320 mV in 1 M KOH. Meanwhile, CoFe₂O₄ samples with three different morphology nanostructures including hollow nanospheres, bulk and nanoparticles have been provided to study the effect of different morphology on NaBH₄ reduction efficiency. As expected, after NaBH₄ reduction, CoFe₂O₄ hollow nanosphere with relatively higher surface area exhibits most obvious improvement for OER activity and also its corresponding reduced CoFe₂O₄ NS showed best OER performance than the reduced CoFe₂O₄ bulk as well as the reduced CoFe₂O₄ nanoparticles, implying the hollow nanospheres feature more accessible surface area than bulk and nanoparticles samples, thus greatly facilitate efficiency of NaBH₄ reduction treatment.     

Spinel NiCo2O4 3-D nanoflowers supported on graphene nanosheets as efficient electrocatalyst for oxygen evolution reaction

Efficient oxygen evolution reaction (OER) electrocatalysts with non-noble metals are very critical for the large-scale exploitation of electrocatalytic hydrogen production systems. To improve the catalytic activity of OER electrocatalysts, several design strategies, such as construction of nanostructures, porous structures and composite materials have been proposed. Herein, spinel NiCo₂O₄ 3-D nanoflowers supported on graphene nanosheets (GNs) are prepared by a simple solvothermal synthesis method as non-noble metal electrocatalysts for OER. The present NiCo₂O₄/GNs composite integrates multiple advantages of nanostructures, porous structures and composite materials, including high surface area, abundant catalytic sites and high stability. Benefiting from the favorable features, the NiCo₂O₄/GNs composite exhibits a better OER performance than NiCo₂O₄ and RuO₂ in alkaline medium, which has a low onset potential (1.50 V), a small Tafel slope (137 mV dec⁻¹). The present work opens a new window for the construction of the carbon-supported 3-D nanostructure of transition metal catalysts with optimizable electrocatalytic performances for electrocatalytic hydrogen production.     

Functionalized Co3O4 graphitic nanoparticles: A high performance electrocatalyst for the oxygen evolution reaction

We describe a novel synthesis technique for the production of graphitic carbon functionalized Co₃O₄ (G/Co₃O₄), which involves the rapid decomposition of cobalt nitrate in the presence of citric acid. Upon immobilization of the G/Co₃O₄ upon Screen-Printed macroElectrodes (G/Co₃O₄-SPEs) the G/Co₃O₄-SPEs were found to exhibit remarkable electrocatalytic properties towards the Oxygen Reduction Reaction (OER). A detailed investigation has been carried out on the influence that the graphitization of the citric acid has, during the course of preparation of Co₃O_4, upon the ability of the G/Co₃O₄ to catalyse the OER within alkaline conditions (1.0 M KOH). The graphitization of citric acid ensures the uniform distribution of Co₃O₄ and enhanced conductivity with maximal exposure of active sites, which are the key parameters to delivering enhanced electrochemical activity. The G/Co₃O₄-SPEs exhibits an overpotential of 304 mV (recorded at 10 mA cm⁻²), a Tafel slope of 110 mV dec⁻¹ and remain stable in its signal output (achievable current density) at varying temperatures (5–50 °C), and after 10 h of chronoamperometry in 1.0 M KOH. The G/Co₃O₄-SPE's OER activity was found to be superior to that of bulk and nano Co₃O₄. The results exhibited within this study will enable production of high-performance and environmentally benign electrocatalysts towards the OER for use within water splitting devices.     

Co-based coordination polymer-derived Co3S4 nanotube decorated with NiMoO4 nanosheets for effective oxygen evolution reaction

The design and construction of novel electrocatalysts are necessary for oxygen evolution reaction (OER). In particular, interface/surface engineering is an effective way to modify active sites and facilitate electron transfer, thereby improving OER performance. Herein, Co-based coordination polymer-derived hollow Co₃S₄@NiMoO₄ nanotube was synthesized via a facile two-step solvothermal/hydrothermal method. [Co(C₄H₇NO₄)]·xH₂O (Co-Asp, Asp = l-aspartic acid) nanowire as morphological template to prepare hollow Co₄S₃ nanotube through the anion exchange. Then, Co₄S₃ was transformed into Co₃S₄ and NiMoO₄ nanosheets were deposited on the surface of the Co₃S₄ nanotube in hydrothermal reaction. The hollow Co₃S₄ nanotube effectively avoids the aggregation of NiMoO₄ nanosheets during the synthesis process. In addition, hollow Co₃S₄@NiMoO₄ nanotube has dramatically increased surface area and more exposed active catalytic sites. Compared to a single Co₄S₃ and NiMoO₄, hollow Co₃S₄@NiMoO₄ nanotube exhibits good electrocatalytic OER performance with Tafel slopes of 102 mV dec⁻¹ and a current density of 10 mA cm⁻² at overpotential of 320 mV in 1.0 M KOH. At higher current density, the OER performance of hollow Co₃S₄@NiMoO₄ nanotube is as good as that of commercial RuO₂. More importantly, this work provides a novel template for interface/surface engineering, which can applied in other fields.     

Double doping of V and F on Co3O4 nanoneedles as efficient electrocatalyst for oxygen evolution

Rationally designing high-activity catalyst for oxygen evolution reaction (OER) is of primary importance due to its sluggish kinetic process in water splitting. Herein, we report a metallic (V) and nonmetallic (F) double doping in Co₃O₄ with nanoneedles structure, which is synthesized through facile oil bath and annealing. Electrochemical measurements show that the Co₃O₄ dopped with fluorine and vanadium (F_0.2-V-Co₃O₄-350) only needs a low overpotential of 320 mV to afford a current density of 10 mA cm^?2, which is superior to commercial RuO₂. The excellent electrocatalytic performance can be attributed to double doping of vanadium and fluorine which have strong electron absorption effect to optimize the density of electrons in Co₃O₄. Besides, nanoneedles structure can enlarge exposure of active sites. And its great durability is evaluated through 2000 cycles CV test. Furthermore, the optimal ratio of fluorine to vanadium and different annealing temperatures of the target catalyst are explored reasonably.     

Fe doped metal organic framework (Ni)/carbon black nanosheet as highly active electrocatalyst for oxygen evolution reaction

To alleviate the sluggish oxygen evolution reaction (OER) kinetics, it's urgent to develop electrocatalysts with high activity and low cost. In this work, Fe doped metal organic frameworks (Ni)/carbon black composites were synthesized via a facile hydrothermal method. Benefiting from the direct use of metal organic frameworks (MOFs) for OER, numerous and highly dispersed active sites are exposed to the electrolyte and reactants. By regulating Ni/Fe ratios, a high electrochemical active surface area (ECSA) and high relative surface content of active Ni³⁺ species are obtained, which mainly contribute to the high OER activity. Besides, the introduced carbon black (CB) was found to enhance the charge-transfer efficiency of the electrocatalysts, which is also favorable for OER. The optimal Ni9Fe1-BDC-0.15CB electrocatalyst shows excellent OER activity with the low overpotential of ~290 mV at 10 mA cm⁻² and the Tafel slope of ~76.1 mV dec⁻¹, which is comparable to RuO₂ and other MOFs-based OER electrocatalysts reported in recent years.     

Three-dimensional Co3O4@NiCo2O4 nanoarrays with different morphologies as electrocatalysts for oxygen evolution reaction

Oxygen evolution reaction is one of the key factors restricting the whole process of electrolysis of water. In this paper, hydrothermal and calcination method are used to in situ grow Co₃O₄@NiCo₂O₄ on nickel foam (NF). The formation of Co₃O₄@NiCo₂O₄ nanostructures depends on the different hydrothermal time, which further results in the different growth mechanism of Co₃O₄@NiCo₂O₄ nanostructures. The result shows that Co₃O₄@NiCo₂O₄-8h, as a catalytic material, could play a synergistic role to largely accelerate the electron transfer process and could be efficiently and persistently used in oxygen evolution reaction. The oxygen evolution reaction activity of Co₃O₄@NiCo₂O₄-8h material is significantly improved compared with Co₃O₄, Co₃O₄@NiCo₂O₄-6h and Co₃O₄@NiCo₂O₄-10 h. When the current density is 50 mA cm⁻², the overpotential is only 290 mV for Co₃O₄@NiCo₂O₄-8h material. The enhanced activity Co₃O₄@NiCo₂O₄-8h is attributed to more active site exposure, rapid charge transfer and synergistic catalysis of Co₃O₄ and NiCo₂O₄. This work provides a new idea for the development of efficient, stable and environmentally friendly hybrid catalysts.     

3D MnCo2O4@CoS nanoarrays with different morphologies as an electrocatalyst for oxygen evolution reaction

The efficiency and stability of electrocatalysts are the key factors for measuring oxygen evolution reaction. In this work, the MnCo₂O₄ structure assembled from well-arranged nanowires or nanosheet arrays has been grown vertically on nickel foam by in-situ hydrothermal method. Interestingly, different morphology of MnCo₂O₄ can be easily regulated by adding NH₄F to a mixed solvent to achieve conversion from nanowires to nanosheets. In addition, further synthesis of unique three-dimensional hierarchical core/shell MnCo₂O₄@CoS nanowires or nanosheets arrays was performed primarily by electrochemical deposition. Both MnCo₂O₄@CoS-7 cycles nanowires and MnCo₂O₄@CoS-7 cycles nanosheets exhibit high efficiency and long-lasting stability for the oxygen oxidation reaction. The lower overpotential of only 280 mV and 270 mV at 20 mA cm⁻² for the MnCo₂O₄@CoS-7 cycles nanowires and MnCo₂O₄@CoS-7 cycles nanosheets were obtained with lower Tafel slopes of 139. 19 mV dec⁻¹ and 131.81 mV dec⁻¹ in 1.0 M potassium hydroxide respectively comparing with our other MnCo₂O₄@CoS catalysts. The results demonstrate that the crystal morphology of MnCo₂O₄@CoS does not significantly influence their electrocatalytic activity in water oxidation reactions by comparing nanostructured MnCo₂O₄@CoS nanowires and MnCo₂O₄@CoS nanosheets. The high catalytic activity of the MnCo₂O₄@CoS nanoarrays is attributed to the possession of more active sites, larger specific surface area, abundant oxygen vacancy, and fast electron transport rate. Not only that, the durability of the MnCo₂O₄@CoS nanoarrays is also excellent after continuous oxygen evolution test of 1000 cycles. The results of XRD, SEM and XPS show that MnCo₂O₄@CoS-7 cycles nanowires and MnCo₂O₄@CoS-7 cycles nanosheets materials can be used as a highly efficient and stable catalyst for oxygen evolution reaction.     

Three-dimensional VOx/NiS/NF nanosheets as efficient electrocatalyst for oxygen evolution reaction

Developing effective and robust electrocatalysts that are applicable for intense conditions is promising for variable industrial oxygen evolution reaction (OER). Herein, we have developed a simple hydrothermal strategy to construct a three dimensional nanoflower-like VOx nanosheets (VOx/NiS/NF) that utilizes S-modified NF as substrate. NiS/NF can provide not only high-surface area for the growth of VOx but also better conductivity and stability derived from NiS. XRD shows the formation of amorphous VOx supported on NiS/NF. XPS confirms the existence and valence state of V, Ni and S. EDX and SEM elemental mapping reveal the composition and great distribution of V, O, Ni and S. SEM and TEM show that the thin VOx nanosheets covered on the surface of NiS/NF uniformly, which implying more exposed active sites. OER measurements display that VOx/NiS/NF has the outstanding catalytic activity with the lower overpotential (330 mV, 50 mA cm⁻²), smaller tafel slope (121 mV dec⁻¹) and lower value of semicircle of EIS than VOx/NF. The modification of NF may be the key for enhancement performances for OER due to reduced charge transfer resistance. The strong durability of VOx/NiS/NF may be attributed to the tighter integration between VOx and NiS/NF in alkaline electrolytes. The impressive results may provide a new strategy to design suitable substrate with good dispersion and conductivity to prepare effective electrocatalysts for OER.     

Zeolitic-imidazolate frameworks-derived Co3S4/NiS@Ni foam heterostructure as highly efficient electrocatalyst for oxygen evolution reaction

Transition metals sulfide-based nanomaterials have recently received significant attention as a promising cathode electrode for the oxygen evolution reaction (OER) due to their easily tunable electronic, chemical, and physical properties. However, the poor electrical conductivity of metal-sulfide materials impedes their practical application in energy devices. Herein, firstly nano-sized crystals of cobalt-based zeolitic-imidazolate framework (Co-ZIF) arrays were fabricated on nickel-form (NF) as the sacrificial template by a facile solution method to enhance the electrical conductivity of the electrocatalyst. Then, the Co₃S₄/NiS@NF heterostructured arrays were synthesized by a simple hydrothermal route. The Co-ZIFs derived Co₃S₄ nanosheets are grown successfully on NiS nanorods during the hydrothermal sulfurization process. The bimetallic sulfide-based Co₃S₄/NiS@NF-12 electrocatalyst demonstrated a very low overpotential of 119 mV at 10 mA cm^?2 for OER, which is much lower than that of mono-metal sulfide NiS@NF (201 mV) and ruthenium-oxide (RuO₂) on NF (440 mV) electrocatalysts. Furthermore, the Co₃S₄/NiS@NF-12 electrocatalyst showed high stability during cyclic voltammetry and chronoamperometry measurements. This research work offers an effective strategy for fabricating high-performance non-precious OER electrocatalysts.     

Defect-rich high-entropy oxide nanospheres anchored on high-entropy MOF nanosheets for oxygen evolution reaction

In this work, high-entropy oxide nanoparticles (HEO NPs)/high-entropy metal-organic framework (HE-MOF) heterostructure electrocatalysts for oxygen evolution reaction (OER) are constructed by in-situ growth of HEO NPs on HE-MOF using partial-localized pyrolysis strategy, and the effect of pyrolysis temperature on the OER performance are studied. The results indicate that the well-dispersed HEO NPs are rich in defects such as oxygen vacancy and lattice distortion, which can increase catalytic active centers. Meanwhile, the nanosheet-like HE-MOF not only acts as the support HEO NPs catalyst but also is kinetically beneficial for fast electrons and ions transportation. Among all the prepared nanostructures, HE-MOF-350-200 shows the best OER performance, achieving a low overpotential of 266 mV at 50 mA cm⁻² along with a satisfactory stability.     

CNT-interconnected iron-doped NiP2/Ni2P heterostructural nanoflowers as high-efficiency electrocatalyst for oxygen evolution reaction

Oxygen evolution reaction (OER) plays a decisive role in electrolytic water splitting. However, it is still challengeable to develop low-cost and efficient OER electrocatalysts. Herein, we present a combination strategy via heteroatom doping, hetero-interface engineering and introducing conductive skeleton to synthesize a hybrid OER catalyst of CNT-interconnected iron-doped NiP₂/Ni₂P (Fe-(NiP₂/Ni₂P)@CNT) heterostructural nanoflowers by a simple hydrothermal reaction and subsequent phosphorization process. The optimized Fe-(NiP₂/Ni₂P)@CNT catalyst delivers an ultralow Tafel slope of 46.1 mV dec^?1 and overpotential of 254 mV to obtain 10 mA cm^?2, which are even better than those of commercial OER catalyst RuO₂. The excellent OER performance is mainly attributed to its unique nanoarchitecture and the synergistic effects: the nanoflowers constructed by a 2D-like nanosheets guarantee large specific area and abundant active sites; the highly conductive CNT skeleton and the electronic modulation by the heterostructural NiP₂/Ni₂P interface and the hetero-atom doping can improve the catalytic activity; porous nanostructure benefits electrolyte penetration and gas release; most importantly, the rough surface and rich defects caused by phosphorization process can further enhance the OER performance. This work provides a deep insight to boost catalytic performance by heteroatom doping and interface engineering for water splitting.     

Controlled synthesis of NiCo2O4@Ni-MOF on Ni foam as efficient electrocatalyst for urea oxidation reaction and oxygen evolution reaction

Heterostructured materials with special interfaces and features give a unique character for much electrocatalytic process. In this work, the introduction of exogenous modifier Ni-MOF improved the reaction kinetics and morphology of the NiCo₂O₄@Ni-MOF/NF catalyst. As-obtained NiCo₂O₄@Ni-MOF/NF has excellent oxygen evolution reaction (OER) performance and urea oxidation reaction (UOR) performance. The catalyst need overpotential of 340 mV at a current density of 100 mA cm^?2 for OER and a potential of 1.31 V at the same current density for UOR. The Tafel slopes of NiCo₂O₄@Ni-MOF/NF is 38.34 and 15.33 mV dec^?1 for OER and UOR respectively, which is more superior than 78.58 and 66.73 mV dec^?1 of NiCo₂O₄/NF. The nanosheets microstructure is beneficial to the adsorption and transport of electrolyte and the presence of a large number of mesoporous channels can also accelerate gas release, and then improves activity of the catalyst. Density functional theory calculation demonstrate that NiCo₂O₄ plays a role in absorbing water, while the existence of in situ generated NiOOH can promote the electron transfer efficiency. It is synergies of NiCo₂O₄ and in situ generated NiOOH that enhance the decomposition of water on the surface of the NiCo₂O₄@Ni-MOF/NF. This investigation provides a new strategy for the application of spinel oxide and MOF materials.     

Straightforward preparation of nickel selenide nanosheets supported on nickel foam as a highly efficient electrocatalyst for oxygen evolution reaction

The development of economical, durable, and efficient oxygen evolution reaction (OER) electrocatalysts is essential for large-scale industrial water electrolysis. Here, a straightforward strategy is proposed to synthesize a series of nickel selenide nanosheets supported on nickel foam (NiSe₂/NF) materials by directly selenizing nickel foam substrates at different temperatures under an inert atmosphere. When evaluated as electrocatalysts in OER, the optimal self-supported NiSe₂/NF-350 shows an excellent performance in 1.0 M KOH medium with an overpotential of 458 mV at 100 mA cm^?2, a small Tafel slope of 45.8 mV dec^?1, and a long-term stability for 36 h. Furthermore, the structural and compositional preservation for NiSe₂/NF-350 after stability test was also verified by various characterizations.