A novel nitrogen-deficient g-C3N4 photocatalyst fabricated via liquid phase reduction route and its high photocatalytic performance for hydrogen production and Cr(VI) reduction

Abstract

A facile liquid phase chemical reduction method was developed to synthesize nitrogen-deficient graphitic carbon nitride (FH-g-C3N4) by application of the weak reducibility of formaldehyde in weak acidic solution. The nitrogen defects in g-C3N4 were confirmed by EA, EPR, XPS and EDS. The extra electrons in nitrogen-deficient sites can easily capture photogenerated holes and reduce the recombination of photogenerated electrons and holes. With appropriate amount of nitrogen defects, FH-g-C3N4 possesses the best photocatalytic activity which is 58% higher than that of H-g-C3N4 (without nitrogen defects) and P25 (TiO2) for Cr(VI) reduction, and its hydrogen production rate is twice of the H-g-C3N4. Compared with H-g-C3N4, FH-g-C3N4 has a stronger light absorption capacity, a more negative potential of conduction band, and a stronger reduction capacity. This work could provide significant information for the simple synthesis of nitrogen-deficient g-C3N4 photocatalyst with distinct reduction performance.