Li Qing, Zhang Shaowen, Xia Wenjie, Jiang Xiaoqi, Huang Zhiwei, Wu Xiaomin, Zhao Huawang, Yuan Chung-Shin, Shen Huazhen, Jing Guohua
College of Chemical Engineering, Huaqiao University, Xiamen, Fujian, China.
Department of Civil, Construction and Environmental Engineering, North Dakota State University, USA.
Ecotoxicol Environ Saf. 2022 Apr 1;234:113411. doi: 10.1016/j.ecoenv.2022.113411. Epub 2022 Mar 14.
Formaldehyde (CHOH), a common volatile organic compound, causes many adverse effects on human health. The highly exposed TiO(001) facet possesses a high photodegradation efficiency of CHOH due to its excellent ability to trap photogenerated holes and high density of surface unsaturated Ti atoms (Ti5c) to bind CHOH. However, the rapid recombination of photoinduced electron-hole pairs of TiO(001) limits the photodegradation efficiency. We adopted a strategy of decorating TiO(001) with g-CN quantum dots (QDs), exploiting the quantum effect of g-CNQDs and their combined staggered band structure. This decoration improves the photocatalytic activity of TiO(001). Moreover, the chemical configuration of g-CNQDs/TiO(001) and the combination mode between the g-CNQDs and TiO(001) support were explored in detail using high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) calculations. Following the physiochemical characteristic results, the transport mechanism of photoinduced carriers was further analyzed by ultraviolet photoelectron spectroscopy (UPS), electron paramagnetic resonance (EPR), and Heyd-Scuseria-Ernzerh (HSE) exchange-correlation functional calculations. Finally, the performance and reaction mechanism of the photodegradation of CHOH by TiO(001) and g-CNQDs/TiO(001) were thoroughly investigated. The results show that the g-CNQDs were composed of an N-defect tri-s-triazine supported by TiO(001) via a strong C-O-Ti chemical bond, which accelerated the separation of photoinduced carriers through a Z-scheme route. The photodegradation and mineralization efficiencies of CHOH were significantly promoted by 30% and 60% for g-CNQDs/TiO(001) compared with those of TiO(001). The photodegradation mechanism proceeded as CHOH - dioxymethylene - formate - carbonate - CO. This study provides a surface engineering means to design highly active modified TiO for CHOH photodegradation.
甲醛（CHOH）是一种常见的挥发性有机化合物，会对人体健康造成诸多不利影响。高度暴露的TiO(001)晶面具有优异的捕获光生空穴的能力以及高密度的表面不饱和Ti原子（Ti5c）来结合CHOH，因此对CHOH具有很高的光降解效率。然而，TiO(001)光生电子 - 空穴对的快速复合限制了光降解效率。我们采用了用g - CN量子点（QDs）修饰TiO(001)的策略，利用g - CN量子点的量子效应及其组合的交错能带结构。这种修饰提高了TiO(001)的光催化活性。此外，使用高分辨率透射电子显微镜（HRTEM）、X射线光电子能谱（XPS）和密度泛函理论（DFT）计算详细探究了g - CN量子点/TiO(001)的化学构型以及g - CN量子点与TiO(001)载体之间的结合模式。根据物理化学特性结果，通过紫外光电子能谱（UPS）、电子顺磁共振（EPR）和Heyd - Scuseria - Ernzerh（HSE）交换相关泛函计算进一步分析了光生载流子的传输机制。最后，深入研究了TiO(001)和g - CN量子点/TiO(001)对CHOH光降解的性能和反应机理。结果表明，g - CN量子点由通过强C - O - Ti化学键由TiO(001)支撑的N缺陷三 - s - 三嗪组成，通过Z - 方案途径加速了光生载流子的分离。与TiO(001)相比，g - CN量子点/TiO(001)对CHOH的光降解和矿化效率分别显著提高了30%和60%。光降解机理为CHOH - 二氧亚甲基 - 甲酸酯 - 碳酸盐 - CO。本研究提供了一种表面工程手段，用于设计用于CHOH光降解的高活性改性TiO。
