Ternary Nanohybrids Comprising N-Doped Graphene and WSe2-WO3 Nanosheets Enable High-Mass-Loading Electrodes with Long-Term Stability for Hydrogen Evolution

In this study, we demonstrated a strategy for fabricating unique 2D ternary nanohybrids comprising N-doped graphene (NG) and in-plane WSe2-WO3 (W-W) heterojunction nanosheets (NG/W-Ws) through heat treatment/oxidation processes using a graphene/PANI/WSe2 precursor. PANI served as an exfoliating and N-doping agent and played a crucial role along with graphene in developing a high effective surface area and pore volume. The NG/W-Ws showed a single kinetic reaction (the Volmer-Heyrovsky step) with a single onset potential for the hydrogen evolution reaction (HER) and decreased overpotentials; this was attributed to the intercalated NG. Density functional theory calculations indicated that NG decreases the energy gap between the LUMO and HOMO levels, and the differential Gibbs free energy of atomic hydrogen on the catalyst surface was close to zero. Therefore, the NG/W-Ws presented a linear relationship between their electrocatalytic performance (e.g., onset potential and overpotential) and mass loading (thickness). The total resistance and capacitance of the NG/W-Ws decreased and increased, respectively, with increasing electrode thickness, highlighting the synergy between the NG and W-W components. We believe that the proposed strategy will ensure the facile fabrication of multicomponent 2D heterostructured nanohybrids for high mass-loading electrocatalyst systems and will contribute to the practical commercialization of 2D nanohybrids as electrocatalysts.