First-Principle and Experiment Framework for Charge Distribution at the Interface of the Molybdenum Dichalcogenide Hybrid for Enhanced Electrochemical Hydrogen Generation

In this work, we present a novel hybrid structure, which has been produced by compositing MoSe2 on MoS2. This promising composite originating from two types of two-dimensional (2D) transition-metal chalcogenides can be used as electrocatalyst for catalyzing protons to hydrogen via the so-called hydrogen evolution reaction (HER), in which MoSe2, can play a role as cocatalyst. The crystal structure and morphology have been systematically studied by SEM, TEM, XPS, and XRD technologies. Then, density functional theory (DFT) based first-principle investigation was employed to accurately describe the electronic redistributing behavior by analyzing charge density change at the interface of the hybrid, which could provide theoretical support for material structure design. The optimized Gibbs free energy change and contracted band structure of the hybrid predicted the enhancement on HER activity and have been proved by corresponding experiments. According to HER measurements, enhanced output current density, small Tafel slope, and long-term stability have been achieved on this hybrid owing to compositing MoSe2 cocatalyst on MoS2. Both theoretical and experimental investigation in this work elucidate the potential of this hybrid for electrochemical hydrogen generation and pave a promising pathway for electrocatalyst design solution.