Promoting hydrogen evolution of a g-C3N4-based photocatalyst by indium and phosphorus co-doping

Abstract

An indium and phosphorus co-doped g-C₃N₄ photocatalyst (In,P-g-C₃N₄) was prepared by K₂HPO₄ post-treatment of an indium-doped g-C₃N₄ photocatalyst (In-g-C₃N₄) derived from in situ copolymerization of dicyandiamide and indium chloride. The experimental results and theoretical simulations revealed that the doped indium ions were located between the planes of g-C₃N₄ and phosphorus atoms were introduced into the g-C₃N₄ plane by replacing the carbon atoms, which existed in the form of PN bonds. The co-doping of indium and phosphorus with g-C₃N₄ not only extended its response to the visible light region but also synergistically promoted the separation and migration of photogenerated charge carriers. As a result, the In,P-g-C₃N₄ photocatalyst exhibited a hydrogen evolution rate as high as 4.03 mmol h⁻¹ g⁻¹, ca. 50 times that of pristine g-C₃N₄ (0.08 mmol h⁻¹ g⁻¹).