Effects of Adsorbed F, OH, and CI Ions on Formaldehyde Adsorption Performance and Mechanism of Anatase TiO2 Nanosheets with Exposed {001} Facets

摘要

Formaldehyde (HCHO), as the main indoor air pollutant, is highly needed to be removed by adsorption or catalytic oxidation from the indoor air. Herein, the F~-, OH~-, and Cl~--modified anatase TiO2 nanosheets (TNS) with exposed {001} facets were prepared by a simple hydrothermal and post-treatment method, and their HCHO adsorption performance and mechanism were investigated by the experimental analysis and theoretical simulations. Our results indicated that the adsorbed F~-, OH~-, and Cl~- ions all could weaken the interaction between the HCHO and TNS surface, leading to the serious reduction of HCHO adsorption performance of TNS. However, different from F~- and Cl~- ions, OH~- ion could induce the dissociative adsorption or HCHO by capturing one H atom from HCHO, resulting m the formation of one formyl group and one H2O-like group. This greatly reduced the total energy of the HCHO adsorption system. Thus, the adsorbed OH~- ions could provide the additional active centers for HCHO adsorption. As a result, the NaOH~-treated TNS showed the best HCHO adsorption performance mainly because its surface F~- was replaced by OH~-. This study will provide new insight into the design and fabrication of high performance adsorbents for removing indoor HCHO and, also, will enhance the understanding of the HCHO adsorption mechanism.