Dual modulation steering electron reducibility and transfer of bismuth molybdate nanoparticle to boost carbon dioxide photoreduction to carbon monoxide

Abstract

Owing to the exorbitant CO2 activation energy and unsatisfactory photogenerated charge separation efficiency, CO2 photoconversion still faces enormous challenges. In this study, a directional electron transfer channel has been established by decorating N-doped carbon quantum dots (N-CQDs) on the surface of Bi4MoO9 nanoparticles to ensure that more active electrons can participate in the CO2 reduction. The conduction band of Bi4MoO9 nanoparticles is calculated to be −1.55 eV versus the normal hydrogen electrode (NHE), pH = 7, which is negative enough to attain the photocatalytic CO2 reduction potential of −0.53 eV versus NHE, pH = 7. CO2 adsorption curves and in situ Fourier transform infrared spectra reveal that N-CQDs facilitate surface CO2 adsorption and activation, as well as CO desorption. In addition, steady-state photoluminescence and photoelectrochemical tests prove that the charge separation efficiency can be greatly enhanced by constructing N-CQDs/Bi4MoO9 composites. In the presence of pure water, N-CQDs/Bi4MoO9-2 composite achieved a CO yield of 16.22 μmol g−1 after 5 h Xe light illumination, which was 3.24 times higher than that of pure Bi4MoO9 (4.98 μmol g−1). This study offers a distinctive approach to the optimization of Bi4MoO9 photocatalysts and their application in energy conversion.