Construction of Z-scheme heterojunction g-C3N4/CQDs/InVO4 with broad-spectrum response for efficient rhodamine B degradation and H2 evolution under visible light

BACKGROUND A Z-scheme structured photocatalyst is a highly efficient photocatalyst for hydrogen evolution and degradation of pollutants. RESULTS An indirect Z-scheme heterojunction g-C3N4/CQDs/InVO4 with carbon quantum dots (CQDs) as electron mediator was constructed and was successfully synthesized using a facile hydrothermal method. The photocatalytic activity of the as-prepared composite was evaluated in terms of hydrogen generation and degradation of rhodamine B (RhB) dye. The as-prepared sample CV20/CQDs2 (g-C3N4/2 wt% CQDs/20 wt% InVO4) exhibits the best photocatalytic activity towards hydrogen production and RhB degradation. Within 90 min, 99.6% of RhB is removed, and the degradation rate constant of RhB over CV20/CQDs2 is 0.06491 min(-1), which is 43.9, 6.64 and 3.3 times as high as that of InVO4, g-C3N4 and binary composite g-C3N4/InVO4. CV20/CQDs2 exhibits H-2 evolution rate of 2.169 mmol g(-1) h(-1), which is 26.07, 2.65 and 1.6 times as high as that of InVO4, g-C3N4 and g-C3N4/InVO4. CONCLUSIONS The enhanced photocatalytic activity is attributed to two aspects. First, CQDs, as electron mediator, promote the effective separation of photogenerated electrons and holes through Z-scheme charge transfer pathway, preserving the high redox ability of electrons and holes. Second, g-C3N4/CQDs/InVO4 shows strong optical absorption in the full visible-light region. (c) 2021 Society of Chemical Industry (SCI).

Automated summary

The study synthesized an efficient Z-scheme heterojunction photocatalyst and promoted the effective separation of photogenerated electrons and holes through Z-scheme charge transfer pathway, enhancing the photocatalytic activity.