Photoreduction of carbon dioxide in the presence of H2, H2O and CH4 over TiO2 and ZnO photocatalysts

• Photoreduction of CO2 by photocatalysts (TiO2 and ZnO) on mesh network was investigated.
• The photoreduction of CO2 in the TiO2 photocatalyst with H2O reductant had highest conversion.
• Best conversion efficiency for ZnO was achieved in the presence of CH4 molecules.
• The conversion products in the presence of CH4 as reductant can be formate and acetate derivatives.
• The conversion products in the presence of H2 can be assigned to the methane and formic derivatives.

In this study, efficiency of the prepared photocatalysts (TiO2 and ZnO) on stainless steel mesh network was examined for photoreduction of CO2 gas. The experiments were performed under direct UV irradiation in a self-designed batch reactor. UV–visible spectra and XRD pattern showed that crystalline structure of the particles did not change in calcinations process. Also, SEM images indicated that semiconductors were well coated on the surface of the mesh. Conversion results showed that photoreduction of CO2 in the presence of TiO2 photocatalyst with H2O reductant had highest conversion. However, the best conversion efficiency for ZnO was achieved in the presence of CH4 molecules. The conversion products in the presence of CH4 as reductant can be formate and acetate derivatives, whereas the conversion products in the presence of H2 can be assigned to the production of methane and formic derivatives.