Photocatalytic Decomposition of Gaseous HCHO over Ag Modified TiO₂ Nanosheets at Ambient Temperature.

Ag nanoparticles loaded onto TiO₂ nanosheets with exposed {001} facets were synthesized by solvothermal hydrolysis and photoreduction deposition methods. The results suggested that Ag NPs were uniformly dispersed on the surface of anatase TiO₂ NSs with a metallic state. The Raman scattering and visible light absorption performances of Ag/TiO₂ NSs were enhanced by Ag NPs due to their surface plasmon resonance effect. Photocatalytic oxidation experiments for HCHO were carried out under visible light, and the enhanced photocatalytic activity of Ag/TiO₂ NSs can be attributed to the synergistic effects of the following factors: (1) the {001} facets, which possessed higher surface energy, showed higher photocatalytic activity; (2) the Ag NPs, the increased oxygen vacancies, and O₂ adsorption on {001} facets can trap photoelectrons, thus inhibiting the recombination of photoelectrons and holes; (3) the Ag NPs can extend the light response range of TiO₂ into visible light. The in situ FTIR results showed that higher mineralization efficiency of HCHO was achieved on Ag/TiO₂ NSs than on Ag/TiO₂ NPs. Additionally, the mechanism for HCHO photocatalytic oxidation was also discussed.