TiO₂ surfaces self-doped with Ag nanoparticles exhibit efficient CO₂ photoreduction under visible light

Doping with intrinsic defects to enhance the photocatalytic performance of TiO₂ has recently attracted attention from many researchers. In this report, we developed an original approach to realise stabilized surface doping using intrinsic defects with the loading of Ag nanoparticles (AgNPs) on the surface. Herein, atmospheric pressure dielectric barrier discharge (DBD) cold plasma was used to help load the AgNPs, and ethanol treatment was used to introduce intrinsic defects (oxygen vacancies and Ti³⁺) on the surface of materials. This method avoids environmentally hazardous reducing regents and is undertaken under atmospheric pressure, thus reducing energy-consuming and complex operation. We combine the advantages of noble metal nanoparticles and surface doping to enhance the photocatalytic performance under the visible light. The characterization of the materials indicates that the loading of AgNPs and introduction of intrinsic defects can change the electronic structure of the composite material and improve its efficiency. The samples show significant enhancement in CO₂ photoreduction to obtain CO and CH₄, with yields reaching 141 μmol m^-2 and 11.7 μmol m^-2, respectively. The formation mechanism of the method for TiO₂ modification and CO₂ reduction is also discussed.