近日，广东工业大学环境健康与污染控制研究院、环境科学与工程学院安太成教授团队题为《Boosting the photocatalytic degradation of ethyl acetate by a Z-scheme Au-TiO₂@NH₂-UiO-66 heterojunction with ultrafine Au as an electron mediator》的学术论文在Environ. Sci.: Nano (https://doi.org/10.1039/D1EN00225B)杂志上接受发表。论文的第一作者为刘宏利副教授，第二作者为硕士研究生常晓宜，通讯作者为安太成教授。该研究工作主要是基于光生电子空穴分离增强机制，提出Au纳米簇掺杂NH₂-UiO-66包裹TiO₂构建的Z型异质结光催化剂，成果实现了在可见光照射下典型VOCs的高效净化，并且进一步系统阐明了影响VOCs可见光光催化降解效率的关键因素及其降解机制。

挥发性有机化合物是一类重要的大气污染物，已严重危害人类健康和生态环境。目前极具应用潜力的光催化氧化深度净化VOCs技术，由于其核心的光催化剂一般具有较小的比表面积、窄的光响应范围和光生载流子易复合等特点，导致可见光条件下VOCs的降解效率低，大大限制了光催化氧化技术在VOCs净化方面的实际应用。因此，本文以具有大比表面积、可见光响应以及良好的化学稳定性和热稳定性的NH₂-UiO-66及应用最广泛的TiO₂传统半导体为基础材料，通过“瓶子围绕船法”，在NH₂-UiO-66自组装过程中将Au³⁺/TiO₂原位还原成Au⁰/TiO₂并引入到NH₂-UiO-66骨架材料内部，构建有利于光生载流子空间分离的Z-型异质结光催化剂（Au-TiO₂@NH₂-UiO-66）。实验发现在UV-Vis照射360 min后，Au-TiO₂@NH₂-UiO-66对工业排放的典型VOCs乙酸乙酯的去除率和矿化率分别可高达94.6%和85.0%。通过对光照条件下光生载流子的分离性能和反应活性物种的生成情况进行监测，阐明了Au-TiO₂@NH₂-UiO-66复合催化剂高效光催化降解乙酸乙酯的作用机制，发现TiO₂和NH₂-UiO-66形成了光生载流子空间分离的Z型异质结，保留了两组分中较高的价带和较低的导带位置，使其具有强的氧化还原能力；而分散在NH₂-UiO-66内的超小Au纳米簇不仅由于其优异的局部表面等离子共振效应（LSPR）扩展了其复合材料的光吸收范围、提高了光吸收强度，而且还可以加速TiO₂表面的光生电子转移至NH₂-UiO-66上。最终致使Au-TiO₂@NH₂-UiO-66产生大量的活性氧化物种（如光生空穴和·O^2-、·OH自由基）高效降解乙酸乙酯。该研究成果不仅可以为VOCs的污染治理提供一种高效的可见光光催化氧化方法，而且可以为VOCs的深度净化机制提供有益的探索。

Graphical Abstract：

论文的网址：

https://pubs.rsc.org/en/content/articlelanding/2021/EN/D1EN00225B

论文英文摘要:

TiO₂ based photocatalytic oxidation has been regarded as a promising technology for VOC removal, although it remains challenging in view of the limited visible light response and low photogenerated charge separation efficiency. Herein, a charge space separated Z-scheme Au-TiO₂@NH₂-UiO-66 photocatalyst was synthesized for highly efficient degradation of VOCs by encapsulation of Au and TiO₂ into visible light responsive NH₂-UiO-66 with Au nanoclusters as electron mediators. The obtained Au-TiO₂@NH₂-UiO-66 nanocomposite could broaden the light absorption of TiO₂ from the UV to visible region due to the excellent localized surface plasmon resonance of Au nanoclusters confirmed by UV-vis diffuse reflectance. Furthermore, electron paramagnetic resonance, photoelectrochemical measurements, steady-state PL spectra and time-resolved PL spectra unveil that the Au-TiO₂@NH₂-UiO-66 ternary photocatalyst followed the Z-scheme mechanism and the ultrafine Au on this heterojunction as an electron mediator can significantly accelerate photogenerated electron transfer. Due to the enhanced interfacial electron transfer by the Au electron mediator and high redox abilities of photogenerated carriers in the Z-scheme heterojunction, the Au–TiO₂@NH₂-UiO-66 nanocomposite greatly boosted the separation efficiency of photogenerated electron–hole pairs, thus producing abundant strong oxidative species, including photogenerated holes, ^•O²⁻ and ^•OH radicals, to mineralize VOCs. Impressively, the mineralization efficiency reached 85% at 94.6% ethyl acetate degradation over the 1 wt% Au-TiO₂@NH₂-UiO-66 photocatalyst within 360 min of xenon lamp irradiation, which was 12.1, 10.6 and 2.83 times higher than that of TiO₂, NH₂-UiO-66 and TiO₂@NH₂-UiO-66, respectively. This work would provide a valuable guideline in the synthesis of highly efficient visible light responsive photocatalysts for VOC degradation.

项目资助：该研究工作得到了国家自然科学基金（41991314, 41731279和22076028）、广东省重点研发项目（2019B110206002）和珠江人才计划本土创新团队项目（2017BT01Z032）的支持。