Synergistic electrocatalytic activity unveiled: Cu–Mo bimetal sulfo-selenide nanocomposite for hydrogen evolution reaction

Developing an affordable and abundant electrocatalyst for generating green hydrogen is crucial for achieving sustainable energy with zero carbon emissions. In this context, nanostructured transition metal chalcogenides were seen as ideal cathode materials for water splitting due to their tuneable structure, large surface area, strong conductivity, and widespread availability. Herein, we have developed Cu–Mo Bimetal Sulfo-Selenide Nanocomposite (CuMoSSe) by incorporating Cu into the MoSSe system through a single-step hydrothermal method and explored it as a catalyst for electrochemical hydrogen evolution. The Cu_0.25Mo_0.75SSe, consisting of a Cu₂Se/MoSSe composite structure, exhibited excellent electrochemical HER activity with an overpotential of 290 mV vs. RHE at 10 mA/cm² compared to its various compositions and pristine counterparts, with remarkable stability for more than 1500 cycles and 12 h in an acidic medium. The enhanced electrochemical activity with smaller charge-transfer resistance (47.8 Ω) and larger double-layer capacitance (14.74 mF/cm²) values with a low Tafel slope of 79.1 mV/dec can be attributed to the effective kinetics and enhanced electrical conductivity of the composite due to the hybrid structure which is backed by the decrease in Gibbs free energy value calculated through theoretical studies. These discoveries open the door to creating new electrocatalysts using combinations of MoSSe and Cu or other metals. This approach aims to design electrode materials that are not only low cost but also mechanically strong and electrically conductive for the process of electrocatalytic water splitting.