Rational modulation of p-n homojunction in P-doped g-C₃N₄ decorated with Ti₃C₂ for photocatalytic overall water splitting

As a metal-free polymeric semiconductor, graphitic carbon nitride (g-C₃N₄) is a promising candidate for photocatalytic water splitting but suffers from the insufficient optical absorption and sluggish utilization of photocarriers. Herein, based on the energy band engineering theory, a new design philosophy of tunable p-n homojunction is proposed and realized in a novel P-doped g-C₃N₄ (PCN) material. Through regulating the tendency of transformation in p-n homojunction, a strong internal electric field is built and integrated with two secondary internal electric fields by further decorating with Ti₃C₂, leading to the formation of a triple-internal electric field system. Thus the spatial separation efficiency of photocarriers is improved and their lifetime is prolonged. The specific photocatalyst exhibits excellent overall water splitting performance in pure water with a notable quantum yield. This work presents a peculiar concept of adjustable p-n homojunction and holds great significance for the rational design of advanced photocatalyst in water splitting.