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

Abstract 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 .