Construction Z-scheme heterostructure by WO3 nanocubes embedded g-C3N4 nanosheets with n-π* electronic transition for enhanced visible light driven photocatalysis

Abstract

The efficient exploitation of visible light while optimizing the charge migration of the photocatalysts is a critical strategy to achieve a significant enhancement of solar energy conversion efficiency. Herein, a g-C₃N₄/WO₃ (P/W-x%) Z-scheme heterojunction photocatalyst was successfully engineered by incorporating unique WO₃ nanocubes into g-C₃N₄ nanosheets with n-π* electronic transition (PCN). Under visible light irradiation, the optimized P/W-2 % presents excellent photocatalytic H₂ production of 3.82 mmol h⁻¹ g⁻¹, which is 13.2 and 3.9 times higher than that of BCN and PCN, respectively. The excellent photocatalytic H₂ production is attributed to the n-π* electronic transition of the lone electron of the N atoms in g-C₃N₄, which enhances the visible light trapping ability. More importantly, In-situ X-ray photoelectron spectroscopy (ISI-XPS) measurement confirms the transport of photo-generated electrons from WO₃ nanocubes to PCN nanosheets. Consequently, a Z-scheme P/W-2 % heterojunction is proposed based on the flow direction of photogenerated electrons in combination with the energy band structure. It not only promotes the rapid separation and migration of photogenerated carriers, but also enhances the reduction capability. This study provides a valuable design idea to enhance the performance of photocatalytic H₂ production via light absorption and charge dynamics.