Surface engineered carbon quantum dots for efficient photocatalytic hydrogen peroxide production
Wenyuan Han, Hao Zhang, Degang Li, Wenwu Qin, Xuliang Zhang, Shaobin Wang, Xiaoguang Duan
Abstract
Photocatalytic production of hydrogen peroxide (H 2 O 2 ) from O 2 and water offers a sustainable and environmentally friendly approach to solar-to-chemical energy conversion. To address the low H 2 O 2 yield of pristine carbon quantum dots (CQDs) (354 µmol g −1 h −1 ), we applied molecular level engineering of CQDs through surface NH functionalization (CQDs-NH), which significantly increased photocatalytic activity of H 2 O 2 production to 2974 µmol g −1 h −1 . This enhanced performance is attributed to the C N-NH- group in CQDs-NH, which improves light absorption, facilitates carrier separation and transfer, increases the selectivity of two-electron oxygen reduction reaction, and promotes oxygen adsorption. Additionally, the hydrogen atom in the C N-NH- group acts as a proton conductor, which significantly promoted the proton-coupled electron transfer process to produce H 2 O 2 in the presence of O 2 . Moreover, a high H 2 O 2 production capacity of 2764 µmol g −1 h −1 was obtained even in the absence of an electron donor. • CQDs as effective photocatalysts for H 2 O 2 production. • NH-functionalized CQDs boost photocatalytic performance. • C N-NH- group aids H 2 O 2 production via proton-coupled electron transfer. • Advanced analysis and DFT calculations provide insights in the mechanism.