Exploring the Capability of Cu-MoS2 Catalysts for Use in Electrocatalytic Overall Water Splitting.

Abstract

Herein, we prepare MoS2 and Cu-MoS2 catalysts using the solvothermal method, a widely accepted technique for electrocatalytic overall water-splitting applications. TEM and SEM images, standard tools in materials science, provide a clear view of the morphology of Cu-MoS2. HRTEM analysis, a high-resolution imaging technique, confirms the lattice spacing, lattice plane, and crystal structure of Cu-MoS2. HAADF and corresponding color mapping and advanced imaging techniques reveal the existence of the Cu-doping, Mo, and S elements in Cu-MoS2. Notably, Cu plays a crucial role in improving the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) of the Cu-MoS2 catalyst as compared with the MoS2 catalyst. In addition, the Cu-MoS2 catalyst demonstrates significantly lower overpotential (167.7 mV and 290 mV) and Tafel slopes (121.5 mV dec-1 and 101.5 mV dec-1), standing at -10 mA cm-2 and 10 mA cm-2 for HER and OER, respectively, compared to the MoS2 catalyst. Additionally, the Cu-MoS2 catalyst displays outstanding stability for 12 h at -10 mA cm-2 of HER and 12 h at 10 mA cm-2 of OER using chronopotentiaometry. Interestingly, the Cu-MoS2‖Cu-MoS2 cell displays a lower cell potential of 1.69 V compared with the MoS2‖MoS2 cell of 1.81 V during overall water splitting. Moreover, the Cu-MoS2‖Cu-MoS2 cell shows excellent stability when using chronopotentiaometry for 18 h at 10 mA cm-2.