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

Abstract

The charge separation ability and CO 2 adsorption capacity of photocatalysts are considered to be two very important influencing factors in photocatalytic CO 2 reduction reactions. In this study, mesoporous g-C 3 N 4 (MCN) with high specific surface area is synthesized by constructing a mesoporous structure to quantify the relationship between the CO 2 adsorption capacity and the photocatalytic CO 2 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 mesoporous structure (strong adsorption capacity of CO 2 ) and Ag particles (effective charge separation) can significantly enhance the photocatalytic activity. The CO evolution rate of 3.0%Ag/mesoporous g-C 3 N 4 (Ag/MCN) reaches 1.66 μmol∙g −1 ∙h −1 , which is 2.81, 2.41 and 4.37 times that of pristine MCN, 1.0% Ag/bulk g-C 3 N 4 (Ag/BCN) and pristine bulk g-C 3 N 4 (BCN), respectively. The study provides useful insight into the development of photocatalysts with high activity for CO 2 reduction via controlled structure and surface modification engineering. • A Ag loaded mesoporous g-C 3 N 4 photocatalyst was prepared for CO 2 reduction. • The effect of CO 2 adsorption capacity on photocatalytic activity was quantified. • The effect of Ag loading on promoting charge separation was confirmed. • The synergistic mechanism of mesoporous and Ag on CO evolution was clarified.