Effects of Adsorbed F, OH, and Cl Ions on Formaldehyde
Adsorption Performance and Mechanism of Anatase TiO<sub>2</sub> Nanosheets
with Exposed {001} Facets
- Publication date
- Publisher
Abstract
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<sup>–</sup>, OH<sup>–</sup>, and Cl<sup>–</sup>-modified anatase
TiO<sub>2</sub> 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<sup>–</sup>, OH<sup>–</sup>, and Cl<sup>–</sup> 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<sup>–</sup> and Cl<sup>–</sup> ions, OH<sup>–</sup> ion could induce the dissociative adsorption
of HCHO by capturing one H atom from HCHO, resulting in the formation
of one formyl group and one H<sub>2</sub>O-like group. This greatly
reduced the total energy of the HCHO adsorption system. Thus, the
adsorbed OH<sup>–</sup> 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<sup>–</sup> was replaced by OH<sup>–</sup>. 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