In situ formation of ultrathin C3N4 layers on metallic WO2 nanorods for efficient hydrogen evolution

Abstract The number and conductivity of active sites of electrocatalysts have become the main factors for excellent performances for hydrogen evolution reaction (HER). In this work, in situ formation of ultrathin C 3 N 4 layers coating on the surface of metallic WO 2 nanorods (WO 2 @C 3 N 4 ) as electrocatalysts for HER has been realized by a facile dopamine (PDA) coating on WO 3 nanorods precursor and following calcination process. Firstly, the uniform polydopamine (PDA) layer has been coated on the surface of WO 3 nanorods (WO 3 @PDA) through a hydrogen thermal process. The ultrathin C 3 N 4 layers with large graphitization degree after calcination of WO 3 @PDA can improve the conductivity and stability of catalysts during HER. The formation of one dimensional WO 2 nanorods may expose more active sites for HER. Benefited from the synergistic effect between WO 2 and C 3 N 4 layers as well as the protection cap of ultrathin C 3 N 4 layers, the obtained core-shell structured WO 2 @C 3 N 4 nanorods exhibit excellent HER performances and high durability in acidic solution, which only require an overpotential of 98 mV to generate a current density of 10 mA cm −2 . Therefore, this work provides a new strategy for constructing transition metal oxides electrocatalyst with high activity and stability by introducing ultrathin C 3 N 4 layer coupled with 1D nanostructure.