Synthesis of a Z-scheme photocatalyst (P-doped g-C3N4/Bi3+-doped Ag3PO4) and its photocatalytic performance

Abstract

A Z-scheme heterojunction photocatalyst was prepared by combining P-doped carbon nitride (PCN) and Bi3+-doped silver phosphate (BPO). The prepared materials were systematically characterized by SEM, XRD, XPS, FT-IR and electrochemical tests. The photocatalytic performance was investigated under visible light irradiation with tetracycline as the model pollutant. The results revealed that doping phosphorus had a markedly impact on widening the light absorption of PCN by reducing its bandgap. Water and hydroxyl groups adsorbed on the BPO surface increased as a result of bismuth doping. Besides, the photocurrent responses of PCN and BOP were all higher than those of the un-doped ones. Especially, doping phosphorus made valence band of PCN move up, while conduction band of BPO went downwards due to bismuth doping. This facilitated formation of Z-scheme heterojunction between PCN and BPO. Consequently, the photocatalytic activity of BPO/PCN was further enhanced. The pseudo-first-order kinetics constant of tetracycline degradation for BPO/PCN was 62.7, 8.2, 1.9, and 1.3 times higher than that for g-C3N4, PCN, Ag3PO4, and BPO, respectively. Radical trapping experiments confirmed that ·O2− and h+ were major reactive species. Additionally, with BPO/PCN as the anode of photocatalytic fuel cell, the performance on decontamination and electricity generation was significantly enhanced.