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 .