Strong electronic interaction in chromium-molybdenum dual incorporated few-layer cobalt sulfide nanosheets with lattice distortion for efficient bifunctional water splitting

Abstract

The investigation into cost-effective and high-efficiency bifunctional electrocatalysts for electrochemical water splitting is crucial for advancing the conversion efficiency of intermittent energy systems. In this study, a novel dissolution-in situ precipitation method is introduced to synthesize few-layer CoS2 nanosheets incorporating dual cations (Cr, Mo), referred to as Cr/Mo-CoS2. The synergistic influence arising from robust dual dopant-induced coupling interactions and pronounced lattice distortions enhances the rate-determining steps of the HER and OER processes in Cr/Mo-CoS2 by optimizing the adsorption of H* and OOH* intermediates on the catalyst surface. The distinctive pinecone-like structure formed by these nanosheets provides numerous active sites and facilitates electron transfer during reactions. Consequently, the synthesized Cr/Mo-CoS2 nanosheets demonstrate superior catalytic activity, characterized by a low overpotential of 123.8 mV at 10 mA cm−2 for the hydrogen evolution reaction and 310.2 mV at 50 mA cm−2 for the oxygen evolution reaction, coupled with excellent durability in alkaline electrolytes. When utilized as bifunctional electrodes for comprehensive water splitting, Cr/Mo-CoS2 achieves a current density of 10 mA cm−2 at a cell voltage of 1.55 V. This research underscores the critical role of dual-cation doping-induced coupling interactions and significant lattice distortions in augmenting the performance of transition metal chalcogenide electrocatalysts.