Plasmon-assisted photocatalytic CO₂ reduction on Au decorated ZrO₂ catalysts

ZrO₂ is one of the most stable metal oxides which is applicable to various chemical reactions in harsh environments. However, the photocatalytic performance of ZrO₂ is relatively poor due to the negligible use of the solar spectrum caused by the wide bandgap (E_g = 5.3 eV). Here, we report plasmon enhanced Au nanoparticles decorated onto ZrO₂ through a facile tannic acid-reduction method. The Au/ZrO₂ heterojunctions exhibited efficient and stable photocatalytic activity of reducing CO₂ into main CO and CH₄, at the rates of 25.6 μmol g^-1 h^-1 and 5.1 μmol g^-1 h^-1 at most, respectively, approximately 6-fold enhanced compared to the pristine ZrO₂, under simulated solar light. The reduction rates could also be improved over 10-fold under visible light when Au nanoparticles were loaded onto ZrO₂. UV-Vis diffuse reflectance spectra confirmed the enhanced visible-light absorption of Au/ZrO₂ caused by localized surface plasmon resonance (LSPR). Electrochemical impedance spectra (EIS) and photocurrent tests proved the more efficient charge transport and electron-hole separation of Au/ZrO₂ heterojunctions. This study demonstrates an effective strategy of LSPR effects to improve the photocatalytic performances of semiconductors.