Synthesis of SnO2/B-P codoped g-C3N4 nanocomposites as efficient cocatalyst-free visible-light photocatalysts for CO2 conversion and pollutant degradation

Abstract Coping with the gradually increasing worldwide environmental issues, it is highly desired to develop efficient, cheap and visible-light responsive nano-photocatalysts for CO 2 conversion and pollutant degradation. Herein, we have successfully synthesized SnO 2 -coupled boron and phosphorus co-doped g-C 3 N 4 (SO/B-P-CN) nanocomposites as efficient cocatalyst-free visible-light photocatalysts of low cost for both CO 2 conversion and pollutant degradation. It is shown that the amount-optimized SO/B-P-CN nanocomposite exhibits enhanced visible-light activities for CO 2 conversion to CH 4 from CO 2 -containing water by ∼9 times, and for phenol and acetaldehyde degradation by ∼7 times, as compared to the bare CN nanosheets. Moreover, it is confirmed that a large amount of produced hydroxyl radicals on SO/B-P-CN is well responsible for the greatly-enhanced photocatalytic activities. Interestingly, the evaluated quantum efficiency (2.02%) of optimized SO/B-P-CN nanocomposite for photocatalytic CO 2 conversion at λ=420 nm is much higher than other reported result. Mainly based on the surface photovoltage responses and the photocurrent action spectra, it is suggested that the enhanced activity of SO/B-P-CN nanocomposite depends on the extended visible-light absorption from 460 to 550 nm after B-P co-doping, and the promoted charge separation via the dopant-induced surface states and the coupled SO nanoparticles. This work implies that the modified CN nanosheets as cheap nanocomposites display promising applications in the photocatalytic field of CO 2 conversion to useful fuels and pollutant degradation for environmental remediation.