Exploration of vanadium-modified nickel selenide (NiV₂Se₄) bifunctional robust and durable electrocatalyst for alkaline OER and HER

Highly efficient and economical bifunctional OER and HER catalysts for water electrolysis are essential for developing an electrochemical energy conversion process for next-generation hydrogen fuel. In this work, a novel non-precious bifunctional vanadium-modified nickel selenide (NiV₂Se₄) catalyst was synthesized via a hydrothermal approach for water splitting application. The configuration and electrocatalytic activity of the prepared catalyst were investigated by utilizing various physical and electrochemical characterizations. The phase transformation from NiSe₂ to NiV₂Se₄ was confirmed by XRD. The NiV₂Se₄ catalysts exhibit faster catalytic reaction kinetics by achieving a current density of 10 mA cm⁻² at a low overpotential of 225 mV and 125 mV with corresponding small Tafel slope of 68 mV dec⁻¹ and 76 mV dec⁻¹ and long-time stability of 72 h and 82 h for OER and HER, respectively. The higher activity of the prepared catalyst is attributed to the synergistic effects of high-valent V-ions self-coupling in the NiSe₂ lattice. The combined interaction of different valence states ions (Ni, V, Se) in NiV₂Se₄ favours the transport of the charges at the surface of the catalyst, introduces more exposed active sites, and regulates the surface electronic structure of NiSe₂, which consequently causes the faster OER/HER catalytic reaction kinetics and ultimately boost activity. The splendid electrochemical performance of NiV₂Se₄ catalysts is opening a new avenue for stimulating the innovation of transition metal chalcogenides-based bifunctional electrocatalysts for practical water splitting.