Construction of <scp>Z</scp>‐scheme heterojunction <scp>g‐C<sub>3</sub>N<sub>4</sub></scp>/<scp>CQDs</scp>/<scp>InVO<sub>4</sub></scp> with broad‐spectrum response for efficient rhodamine <scp>B</scp> degradation and <scp>H<sub>2</sub></scp> evolution under visible light
Fang‐yan Chen, Lei Cheng, Yubin Tang, Keke Shu, Weilong Shi
Abstract
Abstract 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‐C 3 N 4 /CQDs/InVO 4 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‐C 3 N 4 /2 wt% CQDs/20 wt% InVO 4 ) 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 InVO 4 , g‐C 3 N 4 and binary composite g‐C 3 N 4 /InVO 4 . 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 InVO 4 , g‐C 3 N 4 and g‐C 3 N 4 /InVO 4 . 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‐C 3 N 4 /CQDs/InVO 4 shows strong optical absorption in the full visible‐light region. © 2021 Society of Chemical Industry (SCI).