NiMo₂S₄-VS₂ heterostructure on nickel Foam: A promising electrocatalyst for alkaline oxygen evolution reaction

Abstract

Oxygen Evolution Reaction (OER) is a slow process; therefore, improved kinetics require catalytic active centers and higher charge transfer capacities. In the present study, a novel heterostructure made of nickel molybdenum sulfide and vanadium disulfide supported on nickel foam (NiMo2S4-VS2/NF) substrate is fabricated using a single-step hydrothermal process. The structural, morphological, elemental, and textural properties of the fabricated materials are confirmed via various analytical techniques. Furthermore, at the current density of 10 mA cm−2, the observed overpotentials was approximately 318 mV corresponding to an OER in 1 M potassium hydroxide electrolyte. It also shows a lower Tafel slope of 78 mV/dec with large turnover frequency of 2.56 s−1. The resulting NiMo2S4-VS2/NF showed enhanced charge transfer properties and frequent integrated active sites. Hence the remarkable activity of this catalyst is significantly influenced by the synergistic effect of these combined features and resulted in an efficient overall water splitting. This was ascribed to NiMo2S4 which increases OER at the anode by providing active sites for oxidizing water molecules. In NiMo2S4, Mo and S elements aid to maintain active sites and accelerate reaction kinetics, while Ni sites operate as electrocatalytic efforts for water oxidation. In general, VS2 promotes hydrogen atom recombination into molecular hydrogen while also encouraging HER at the cathode via hydrogen atom adsorption. In general, NiMo2S4-VS2/NF is a suitable option for water splitting applications due to the close proximity of these two components within the structure of the catalyst, which enables charge transfer and surface reactions and also allow for effective OER. This unique approach for designing the catalyst and engineering the heterointerface is a promising strategy to develop novel and efficient OER catalysts.