Dual-channels separated mechanism of photo-generated charges over semiconductor photocatalyst for hydrogen evolution: Interfacial charge transfer and transport dynamics insight

Photocatalytic water splitting to produce hydrogen is one of the most promising strategies to alleviate the energy crisis and environmental pollution. Nevertheless, the rapid recombination of photo-induced electron-hole pairs in the volume phase and surface of the semiconductor photocatalysis severely limits the activity of the photocatalysts. Herein, the hollow tubular carbon nitride (HTCN) was modified by the introduction of S element doping and anchoring carbon dots (CDs) on the surface to prepare CDs/S-HTCN composite, which exhibits boosted photocatalytic hydrogen evolution rate (∼9284 μmol h-1 g-1) compared to and S-HTCN (∼3120 μmol h-1 g-1) and HTCN (∼2086 μmol h-1 g-1). The enhancement of photocatalytic activity is mainly ascribed to the adjusted the electronic structure and optical properties of HTCN by S atoms doping for promoting rapid volume phase charge separation efficiency and captured and stored electrons from conduction band of S-HTCN by CDs loading for accelerating the surface separation efficiency of the electron-hole pairs. This dual-channels separation mechanism of photo-generated charges can provide insights into the development of composite photocatalyst with high activity and stability.