Mesoporous C-doped C3N5 as a superior photocatalyst for CO2 reduction

Use of naturally abundant solar light for CO 2 reduction is a green pathway to reduce carbon footprint. C 3 N 5 is a promising visible-light photocatalyst with enhanced local electron concentration and more active N N sites compared to g-C 3 N 4 . We herein report development of mesoporous C-doped C 3 N 5 through a simple copolymerisation of 3-amino-1,2,4-triazole with trimesic acid via hard-templating method, which demonstrated enhanced light absorption ability and delocalised π-electron density (as evident from density functional theory calculation), resulting in efficient charge transfer to the active surface sites of the photocatalyst. The optimised C-doped mesoporous C 3 N 5 exhibited a superior photocatalytic CO 2 reduction activity with the CO evolution of 116.6 µmol·g −1 , which is 4-fold and 12-fold times higher than that of C 3 N 5 and g-C 3 N 4 respectively. The enhanced photocatalytic CO 2 conversion efficiency can be attributed to the synergetic effects of π-electron modulation by C-doping and enhanced surface-active sites brought by mesoporosity. • C-doped mesoporous C 3 N 5 , exhibits significantly enhanced visible-light absorption and suppresses charge recombination. • By controlling the π-electron distribution through C-doping, we have successfully manipulated the optical properties of C 3 N 5 . • The prepared novel C-doped mesoporous C 3 N 5 shows a 12 times incriment in CO 2 RR to CO, comapred to that of C 3 N 4. • Extended photostability (> 48 h) has been observed without significant loss in conversion efficiency. • Until now, C-doped mesoporous C 3 N 5 systems have not been explored for CO 2 RR.