Enhanced light-driven CO2 reduction on metal-free rich terminal oxygen-defects carbon nitride nanosheets

Exploiting highly-efficient and metal-free photocatalyst for CO2 conversion into useful chemicals is a promising pathway to solve the energy and environmental crises. In this work, through a facile exfoliation process, an ultra-thin and short-range order g-C3N4 nanosheet with rich terminal oxygen defects is successfully constructed, which presents total electron yield of 36.30 lmol g(-1)h(-1), 3.05 times higher than that of bulk one. The results affirms that both the van der Waals forces between the C3N4 layers and the CAN bonds on the periodic heptazine units could be disrupted during the sonication process, thus achieving the ultra-thin and ultra-small g-C3N4 nanosheet, which enables the improvement of optical absorption and carrier separation abilities. The p-conjugated triazine rings structure is still remained but the terminal active C radicals tend to transform into oxygen defects which become the sites to bind and activate CO2 . The in-situ DRIFTS provides the direct evidence that the size regulation and oxygen-defects design strategy can effectively promote the CO2 adsorption and activation process upon the photocatalyst, thus turning out to boost the reactivity toward CO2 . (C) 2021 Elsevier Inc. All rights reserved.

Automated summary

An ultra-thin and short-range order g-C3N4 nanosheet with rich terminal oxygen defects was successfully constructed through a facile exfoliation process, presenting a higher total electron yield. The size regulation and oxygen-defects design strategy were found to effectively promote the CO2 adsorption and activation process upon the photocatalyst.