Enhanced photoreduction activity of CO2 to CO over Ag-loaded mesoporous g-C3N4 (MCN) by promoting charge separation and CO2 adsorption

The charge separation ability and CO2 adsorption capacity of photocatalysts are considered to be two very important influencing factors in photocatalytic CO2 reduction reactions. In this study, mesoporous g-C3N4 (MCN) with high specific surface area is synthesized by constructing a mesoporous structure to quantify the relationship between the CO2 adsorption capacity and the photocatalytic CO2 reduction activity. Moreover, Ag particles functioned as active sites effectively promote the charge separation efficiency and enhance the photocatalytic activity. More importantly, it is confirmed that the synergistic effect between the meso-porous structure (strong adsorption capacity of CO2) and Ag particles (effective charge separation) can significantly enhance the photocatalytic activity. The CO evolution rate of 3.0%Ag/mesoporous g-C3N4 (Ag/MCN) reaches 1.66 mu mol.g(-1).h(-1), which is 2.81, 2.41 and 4.37 times that of pristine MCN, 1.0% Ag/bulk g-C3N4 (Ag/BCN) and pristine bulk g-C3N4 (BCN), respectively. The study provides useful insight into the development of photocatalysts with high activity for CO2 reduction via controlled structure and surface modification engineering. (C) 2022 Elsevier B.V. All rights reserved.