Novel dual Z-scheme Ag-bridged AgI/FeVO4-C3N4 plasmonic heterojunction: A study on the performance and mechanism of photocatalytic reduction of Cr(VI)

Proper design and synthesis of photocatalysts with efficient interfacial charge transfer, strong redox capabilities, and robust environmental applications are essential. Herein, a novel dual Z-scheme Ag-bridged AgI/FeVO4-C3N4 plasmonic heterojunction was successfully synthesized by a chemical deposition method. Compared with FeVO4, FeVO4-C3N4, AgI/C3N4, AgI/FeVO4, and AgI/FeVO4-C3N4, the optimized dual Z-scheme Ag@AgI/FeVO4-C3N4 composite exhibited an excellent photocatalytic reduction of Cr(VI) in water with approximately 100% reduction efficiency within 60 min. The reduction rate of Cr(VI) by Ag@AgI/FeVO4-C3N4 was estimated to be 0.0525 min−1, which was 3.5-fold and 26.2-fold of that by AgI/FeVO4-C3N4 and FeVO4, respectively. In addition, Ag@AgI/FeVO4-C3N4 showed good properties in terms of catalytic activity and 5 cycles stability. Furthermore, the reactive oxygen species •O2- and •OH enhancement processes were further verified by nitroblue tetrazolium (NBT) and terephthalic acid (TA) conversion experiments, respectively. Due to the strong force between AgI and FeVO4-C3N4 and the local surface plasmon resonance (LSPR) effect of Ag, a double Z-scheme heterojunction with rapid electron transfer ability was formed, which improved the photocatalytic performance of Ag@AgI/FeVO4-C3N4. Therefore, the new dual Z-scheme heterojunction Ag@AgI/FeVO4-C3N4 composites have a good application prospect in water purification. This study provides a new idea for the design of high-efficiency double Z-scheme photocatalysts and their application in the field of environmental purification.