Surface Nonpolarization of g-C3N4 by Decoration with Sensitized Quantum Dots for Improved CO2 Photoreduction

Photocatalytic conversion of CO 2 can provide a solution for simultaneously addressing global warming and solar fuel generation. However, its applicability is presently limited by the unsatisfactory photoconversion efficiency of the state-of-art photocatalysts. In this regard, enhancing CO 2 adsorption through surface modification could be an efficient way to improve the photoconversion efficiency. Herein, doping of nonpolar carbon quantum dots (CQDs) onto g-C 3 N 4 is reported for the construction of a metal-free heterojunction photocatalyst (CQDs/g-C 3 N 4 ). CQDs offer several advantages such as band-gap reduction and electron-withdrawing effect to improve light absorption and photocarrier separation efficiency. However, this study reveals that nonpolar CQDs could also improve CO 2 adsorption, photoinduced H 2 production, reaction kinetics, and alter CO 2 photoreduction pathways to generate CH 4 . Consequently, the CQDs/g-C 3 N 4 could generate six times more CO and CH 4 without detectable H 2 compared to pristine g-C 3 N 4 , under similar conditions. Therefore, this study demonstrates a promising strategy for efficient adsorption, activation, and subsequent photoreduction of CO 2 by nonpolar surface modification of g-C 3 N 4 . Graphical Fighting carbon with carbon : Incorporation of nonpolar carbon quantum dots on the surface of g-C 3 N 4 imparts several benefits, including band reduction, improved charge separation, and increased CO 2 adsorption. This enhances reaction kinetics and alters the pathways for photoreduction of CO 2 , thereby enabling efficient CO and CH 4 generation.