LAUSR

Abstract Light harvest is an important part of the photocatalysis process. In this work, phosphorus doped g-C3N4 with outstanding N2 photofixation ability was prepared via microwave treatment. XRD, N2 adsorption, UV–Vis, SEM, XPS, ESR and PL were used to characterize the as-prepared catalysts. Combining the P doping with microwave treatment, the planar and symmetric heptazine units in g-C3N4 was destroyed. This causes that the n-π* electronic transition becomes allowed. The remarkable red shift of absorption edge from 465 nm to near 600 nm was observed, leading to the obviously promoted visible light absorption. The synergy effect of P doping and microwave treatment also enhances the surface area and separation efficiency of electron-hole pairs. The as-prepared catalyst displays the highest NH4+ concentration of 6.5 mg·L−1·gcat−1, over 13.5 times higher than that of neat g-C3N4, as well as the excellent photocatalytic stability.