In Situ Grown Ni ₃ Se ₂ −WSe ₂ Heterostructure toward Accelerated Bifunctional Electrocatalytic Performance in Alkaline Medium

Developing cost-effective and environmentally benign electrocatalysts is crucial for achieving scalable hydrogen and oxygen production through water electrolysis. In this work, we present for the first time the fabrication of a nickel selenide−tungsten selenide (Ni 3 Se 2 −WSe 2 ) heterostructure on nickel foam (NIF) using a simple electrochemical deposition (ECD) approach. The materials prepared using ECD have been subjected to thorough structural, morphological, and valence state analyses. The electrocatalytic efficacy of the prepared modified electrodes was tested toward hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline medium. The engineered Ni 3 Se 2 −WSe 2 /NIF heterostructure demonstrated remarkably improved electrocatalytic performance for both HER and OER. The heterostructure-based electrocatalyst exhibited very low overpotentials of 218 and 370 mV at 100 mA cm −2 in 1.0 M KOH, outperforming the individual components. The sequential in situ formation of Ni 3 Se 2 followed by WSe 2 deposition not only enhanced electrical conductivity but also facilitated the generation of abundant active sites at the heterojunction, resulting in excellent catalytic durability over 24 h of continuous operation for overall water splitting. The superior electrocatalytic performance is due to the strong synergistic coupling between WSe 2 and Ni 3 Se 2 within the heterostructure, which accelerates the charge transfer and optimizes reaction kinetics.