Surface Nonpolarization of g-C3 N4 by Decoration with Sensitized Quantum Dots for Improved CO2 Photoreduction.

Photocatalytic conversion of CO2 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 CO2 adsorption through surface modification could be an efficient way to improve the photoconversion efficiency. Herein, doping of nonpolar carbon quantum dots (CQDs) onto g-C3 N4 is reported for the construction of a metal-free heterojunction photocatalyst (CQDs/g-C3 N4 ). 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 CO2 adsorption, photoinduced H2 production, reaction kinetics, and alter CO2 photoreduction pathways to generate CH4 . Consequently, the CQDs/g-C3 N4 could generate six times more CO and CH4 without detectable H2 compared to pristine g-C3 N4 , under similar conditions. Therefore, this study demonstrates a promising strategy for efficient adsorption, activation, and subsequent photoreduction of CO2 by nonpolar surface modification of g-C3 N4 .