The influence of inorganic anions on photocatalytic CO2 reduction

Abstract

The influence of common inorganic anions on photocatalytic CO₂ reduction has been investigated in a semiconductor/complex (CdS/Co(bpy)₃Cl₂) system. There were significant differences in photocatalytic performance when the reactions occurred in media with various inorganic anions. These results demonstrated that inorganic anions affect the photoreduction of CO₂ through their redox performance, capacity to coordinate with metal cations, and so on. Some inorganic anions, such as NO₃⁻, H₂PO₄⁻, CO₃²⁻, CH₃COO⁻, and SO₄²⁻ showed different degrees of inhibition on the photocatalytic reduction of CO₂, particularly at high concentrations. No significant effect on the catalytic performance was observed at the same concentration of Cl⁻. On the contrary, F⁻ and a low concentration of CO₃²⁻ exhibited a promotion effect on CO evolution. In this paper, the photochemical observations reveal the relationship between inorganic anions and photocatalytic CO₂ reduction performance. Electrochemical/spectrographic measurements suggest possible influencing mechanisms by these anions for CO₂ reduction, which may provide useful information for experimental design and new considerations for addressing highly efficient artificial synthesis.