Fabrication and Density Functional Theory Calculations of Bromine Doped Carbon Nitride Nanosheets with Enhanced Photocatalytic Reduction of CO2 into Solar Fuels

Abstract

A promising technology to address the global environmental challenges and solar-to-fuel conversion development is photocatalysis. Thus, this study was conducted to fabricate ultrathin Br doped g-C3N4 nanosheet for photocatalytic reduction of CO2 into solar fuels. The sample was produced by a mixture of dicyandiamide with ammonium bromide (NH4Br) in water, dried, calcinated, and exfoliated in methanol by ultrasonication. Compared to the pure g-C3N4 NS, the g-C3N4 NS-Br (0.5g) sample exhibited unique characteristics such as high porosity, large surface area, excellent visible light harvesting ability, effective charge separation, and mobility of charge carriers with enhanced photocatalytic CO2 reduction into solar fuels (i.e., CH4 and CH3OH). DFT calculation indicated that the sample possesses an excellent electronic band structure with band-gap energy to be 2.05 eV closed to 2.45 eV obtained from the experiment. The electronic band alignment structure favored a significantly higher CO2 photocatalytic reduction of 0.4 μmolh−1 g −1 of CH4 and 0.6 μmolh−1 g −1 of CH3OH formation, which is 4.0 and 7.5 times higher than the pure g-C3N4 NS. A combination of nanostructure tuning and doping produced a synergistic effect for enhancing photocatalytic activity and have potential applications in various fields.