State Key Laboratory of Advanced Technology for Material Synthesis and Processing, Wuhan University of Technology, Luoshi Road 122#, Wuhan 430070, PR China.
ACS Appl Mater Interfaces. 2013 Aug 28;5(16):8165-72. doi: 10.1021/am402246b. Epub 2013 Aug 19.
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 of HCHO by capturing one H atom from HCHO, resulting in 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.
甲醛（HCHO）作为主要的室内空气污染物，非常需要通过吸附或催化氧化从室内空气中去除。在此，通过简单的水热和后处理方法制备了具有暴露的{001}面的 F(-)、OH(-)和 Cl(-)改性锐钛矿 TiO2 纳米片（TNS），并通过实验分析和理论模拟研究了其 HCHO 吸附性能和机制。结果表明，吸附的 F(-)、OH(-)和 Cl(-)离子都可以削弱 HCHO 与 TNS 表面之间的相互作用，导致 TNS 的 HCHO 吸附性能严重降低。然而，与 F(-)和 Cl(-)离子不同，OH(-)离子可以通过从 HCHO 中捕获一个 H 原子来诱导 HCHO 的离解吸附，从而形成一个甲酰基和一个 H2O 样基团。这大大降低了 HCHO 吸附体系的总能量。因此，吸附的 OH(-)离子可以为 HCHO 吸附提供额外的活性中心。结果，NaOH 处理的 TNS 表现出最佳的 HCHO 吸附性能，主要是因为其表面的 F(-)被 OH(-)取代。这项研究将为设计和制造用于去除室内 HCHO 的高性能吸附剂提供新的见解，并增强对 HCHO 吸附机制的理解。
