School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China; State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China.
J Colloid Interface Sci. 2017 Jun 15;496:522-530. doi: 10.1016/j.jcis.2017.02.054. Epub 2017 Feb 24.
Anatase TiO crystal facets are garnering increasing attention due to their unique surface property. However, no specific linear relationship had been derived between the facet exposed on TiO and the surface adsorption capacity as well as photocatalytic performance. This study systematically explored the facet effects on antimony (Sb) adsorption and photocatalytic oxidation using high-index {201} and low-index {101}, {001}, and {100} TiO. The results suggest that high-index {201} TiO exhibits the best Sb(III) adsorption and photocatalytic activity compared to the low-index TiO. Both the Sb(III) adsorption density and the amount of OH and O generated in solution were correlated to the magnitude of surface energy on TiO facets. Photocatalytically generated OH and O were responsible for Sb(III) photooxidation as evidenced by radical-trapping experiments. The great contribution of OH was observed only on {201}, not on low-index TiO. This phenomenon was found to be attributable to the high surface energy on {201}, which enables the generation of a large amount of photogeneration OH to compensate for the fast rate of OH dissipation. Therefore, the predominant participation of OH in Sb(III) photooxidation was only possible on high-index {201} TiO, which resulted in an enhanced photocatalytic rate. On the other hand, O dominated the Sb(III) photocatalytic oxidation on low-index TiO. The intrinsic facet-dependent adsorption and photocatalytic mechanism obtained from this study would be useful for developing TiO-based environmental technologies.
锐钛矿 TiO 晶面因其独特的表面性质而受到越来越多的关注。然而，TiO 暴露的晶面与表面吸附能力和光催化性能之间并没有特定的线性关系。本研究系统地研究了高指数{201}和低指数{101}、{001}和{100}TiO 晶面对锑（Sb）吸附和光催化氧化的晶面效应。结果表明，与低指数 TiO 相比，高指数{201}TiO 表现出最佳的 Sb(III)吸附和光催化活性。Sb(III)吸附密度以及溶液中生成的 OH 和 O 的量都与 TiO 晶面的表面能大小有关。光催化生成的 OH 和 O 是 Sb(III)光氧化的原因，这一点可以通过自由基捕获实验得到证明。只有在{201}上观察到 OH 的巨大贡献，而在低指数 TiO 上则没有。这种现象归因于{201}上的高表面能，这使得大量的光生 OH 得以产生，以补偿 OH 快速耗散的速率。因此，只有在高指数{201}TiO 上，OH 才能主要参与 Sb(III)的光氧化，从而提高光催化速率。另一方面，O 主导了低指数 TiO 上的 Sb(III)光催化氧化。本研究获得的内在晶面依赖性吸附和光催化机制将有助于开发基于 TiO 的环境技术。
