Abstract
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.
Highlights
Formaldehyde (HCHO) is one of the most common volatile organic compounds (VOCs) in indoor air, which significantly decreases the indoor air quality and further influences human health [1]
These results indicated that the simultaneous exposure of {001} and {101} facets with appropriate proportions could improve the separation of photo-generated holes and electrons [11]
The Ag NP was spherical with an average diameter of 5.0~8.0 nm
Summary
Formaldehyde (HCHO) is one of the most common volatile organic compounds (VOCs) in indoor air, which significantly decreases the indoor air quality and further influences human health [1]. Many efforts have been made to eliminate indoor HCHO, such as adsorption [2,3], thermal catalytic oxidation [4], plasma technology [5], and photocatalytic oxidation [6,7]. Because of their shortcomings: such as limited adsorption capacity, high reaction temperature, demands of high energy consumption, and low efficiency, etc., these methods are limited for the practical application [8]. These results indicated that the simultaneous exposure of {001} and {101} facets with appropriate proportions could improve the separation of photo-generated holes and electrons [11]
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