College of Chemical Engineering, Huaqiao University, Xiamen, Fujian, People's Republic of China.
Department of Civil and Environmental Engineering, North Dakota State University, Fargo, ND, USA.
Environ Sci Pollut Res Int. 2022 Feb;29(10):13805-13821. doi: 10.1007/s11356-021-16459-w. Epub 2021 Oct 1.
TiO-based photocatalysts are a potential technology for removing indoor formaldehyde (CHOH) owing to their strong photooxidation ability. However, their photooxidation performance is generally weakened when suffering from the competitive adsorption of HO. In a method inspired by the oxygen evolution reaction (OER) to generate intermediates with hydroxyl radicals on the anode electrode catalysts, an electric field was employed in this research and applied to the photooxidation of CHOH to prevent the competitive adsorption of HO. Additionally, 0.5-5% FeO decorated TiO was employed to improve the photoelectrocatalytic activity. The influence of an electric field on hydroxyl-radical production was investigated by both density functional theory (DFT) with direct-imposed dipole momentum and photoelectrocatalytic experimental tests. The surface characterization of the photocatalysts, including transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and electron paramagnetic resonance (EPR), was conducted. DFT results show that a positive electric field with a strength of 0.05 Å/V was more favorable to produce hydroxyl on FeO/TiO(010) than was a negative electric field. FeO decoration can significantly boost hydroxyl formation, resulting from a decrease in the binding energy between the Fe of FeO and the oxygen and hydrogen atoms of HO. The dissociated hydrogen atom of the HO preferentially remained on the catalysts' surface rather than being released into the gas flow. The experimental results demonstrated that applying 150 V could not directly enhance the photooxidation of CHOH by either TiO or FeO/TiO but that it could relieve the HO inhibitory effect by more than 10% on the FeO/TiO.
基于 TiO 的光催化剂由于其强大的光氧化能力，是去除室内甲醛 (CHOH) 的一种有潜力的技术。然而，当它们遭受 HO 的竞争吸附时，其光氧化性能通常会减弱。在一种受析氧反应 (OER) 启发的方法中，通过在阳极电极催化剂上产生具有羟基自由基的中间体，本研究中采用了电场来防止 HO 的竞争吸附，以提高 CHOH 的光氧化性能。此外，还采用了 0.5-5% FeO 修饰的 TiO 来提高光电催化活性。通过密度泛函理论 (DFT) 与直接施加偶极矩以及光电催化实验测试，研究了电场对羟基自由基生成的影响。对催化剂的表面特性进行了透射电子显微镜 (TEM)、X 射线光电子能谱 (XPS) 和电子顺磁共振 (EPR) 等表征。DFT 结果表明，与负电场相比，强度为 0.05 Å/V 的正电场更有利于在 FeO/TiO(010) 上产生羟基。FeO 修饰可以显著促进羟基的形成，这是由于 FeO 中的 Fe 与 HO 的氧和氢原子之间的结合能降低所致。HO 的解离氢原子优先保留在催化剂表面，而不是释放到气流中。实验结果表明，施加 150 V 既不能直接增强 TiO 或 FeO/TiO 的 CHOH 光氧化作用，也不能缓解 FeO/TiO 上超过 10%的 HO 抑制作用。
