Photocatalytic reduction of CO₂ over Ag/TiO₂ nanocomposites prepared with a simple and rapid silver mirror method

The photocatalytic reduction of CO₂ over Ag/TiO₂ composites prepared with a simple silver mirror reaction method was investigated under UV-visible irradiation in both gas-phase (CO₂ + water vapor) and aqueous solution (CO₂-saturated NaHCO₃ solution) systems. The as-prepared Ag/TiO₂ nanocomposite exhibits efficient photocatalytic activity due to the surface plasmonic resonance and electron sink effect of the Ag component, which was found to be closely related to the size and loading amount of Ag. The rapid silver method is effective at curbing the size of Ag, so photocatalytic activity can be improved. Diverse organic chemical products were detected, including mainly methane and methanol as well as a small amount of C₂ and C₃ species such as acetaldehyde and acetone. Possible photocatalytic mechanisms were proposed. This artificial photosynthesis process may give a prosperous route to the removal of CO₂ while simultaneously converting CO₂ to valuable fuels based on highly efficient photocatalysts.