Rational Design of Vanadium-Modulated Ni₃Se₂ Nanorod@Nanosheet Arrays as a Bifunctional Electrocatalyst for Overall Water Splitting

Developing highly efficient and cost-effective non-noble metal electrocatalysts with prominent operational stability toward hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is indispensable for large-scale water electrolysis but remains challenging. Here, an innovative superhydrophilic vanadium-modulated Ni₃Se₂ nanorod@nanosheet array in situ grown on nickel foam (V-Ni₃Se₂/NF) is synthesized via a solvothermal strategy employing a NiV-LDH nanosheet as a precursor. Experimental investigations disclose that the hierarchical nanostructure endows V-Ni₃Se₂/NF with abundant electrochemically surface active sites that render the easy accessibility of the electrolyte to the electrode, thereby enhancing the electron transfer efficiency and electrocatalytic activity toward HER and OER. Furthermore, the modulated electronic configuration in V-Ni₃Se₂/NF not only favors the water dissociation and formation of adsorbed hydrogen but also optimizes the binding energy of key reaction intermediates, thus expediting the water electrolysis kinetics. Consequently, the V-Ni₃Se₂/NF electrode requires ultralow overpotentials of 275 and 370 mV at a large current density of 500 mA cm^–2 in 1.0 M KOH solution toward HER and OER, respectively. The assembled V-Ni₃Se₂/NF||V-Ni₃Se₂/NF electrolyzer yields a low cell voltage equaling to 1.56 V to deliver 10 mA cm^–2 together with an extraordinary long-term durability for 80 h, far outperforming the benchmark Pt/C/NF||IrO₂/NF counterpart (1.76 V, 10 mA cm^–2), demonstrating its glorious potentials in large-scale industrial water electrolysis applications. This work puts forward novel synergistic tactics to construct bifunctional electrocatalysts with prominent water splitting performance in a harsh alkaline electrolyte.