Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, Institute of Environmental & Applied Chemistry, College of Chemistry , Central China Normal University , Wuhan 430079 , People's Republic of China.
Environ Sci Technol. 2019 Jun 4;53(11):6444-6453. doi: 10.1021/acs.est.8b07322. Epub 2019 May 13.
Semiconductor photocatalytic technology has great potential for the removal of dilute gaseous NO in indoor and outdoor atmospheres but suffers from unsatisfactory NO-removal selectivity due to undesirable NO byproduct generation. In this study, we demonstrate that the 99% selectivity of photocatalytic NO oxidation toward nitrate can be achieved over blue TiO bearing oxygen vacancies (OVs) under visible-light irradiation. First-principles density functional theory calculation and experimental results suggested that the OVs of blue TiO with localized electrons could facilitate the molecular oxygen activation through single-electron pathways to generate ·O and simultaneously promote the photogenerated hole annihilation. The generated ·O directly converted NO to nitrate, while the hole annihilation inhibited the side-reaction between holes and NO to avoid toxic NO byproduct formation, resulting in the highly selective removal of NO. This study reveals the dual functions of OVs in defective photocatalysts and also provides fundamental guidance for the selective purification of NO with photocatalytic technology.
半导体光催化技术在去除室内和室外大气中的稀气态 NO 方面具有巨大的潜力，但由于生成不理想的 NO 副产物，其 NO 去除选择性仍不尽人意。在本研究中，我们证明了在可见光照射下，具有氧空位 (OVs) 的蓝色 TiO 可以实现 99%的光催化 NO 氧化生成硝酸盐的选择性。第一性原理密度泛函理论计算和实验结果表明，具有局域电子的蓝色 TiO 的 OVs 可以通过单电子途径促进分子氧的活化，生成·O，并同时促进光生空穴的湮灭。生成的·O 可将 NO 直接转化为硝酸盐，而空穴的湮灭抑制了空穴和 NO 之间的副反应，从而避免了有毒的 NO 副产物的形成，实现了对 NO 的高选择性去除。本研究揭示了缺陷型光催化剂中 OVs 的双重功能，也为利用光催化技术选择性净化 NO 提供了基础指导。
