Graduate School, Chiang Mai University, Chiang Mai 50200, Thailand; Department of Chemistry, Center of Excellence for Innovation in Chemistry (PERCH-CIC), Center of Excellence in Materials Science and Technology, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand.
Materials Science Research Center, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand.
J Colloid Interface Sci. 2018 Feb 15;512:105-114. doi: 10.1016/j.jcis.2017.10.047. Epub 2017 Oct 13.
The introduction of oxygen vacancies (V) into tin dioxide crystal structure has been found as an effective method to improve its photocatalytic performance. Herein, oxygen-deficient tin dioxide (SnO) nanocrystals were successfully prepared via a facile, one-step hydrothermal method at the temperature lower than those reported previously. The effect of hydrothermal temperature on phase composition and V content was also firstly investigated. Due to its high oxygen vacancy concentration, the SnO prepared at 80 °C provides the best photocatalytic degradation of methyl orange under UV-visible light. Scavenger trapping and nitroblue tetrazolium experiments also show that the V act as electron trapped sites and molecular oxygen adsorption sites, therefore increasing the production of active O radical which is the main species governing the photocatalytic activity of SnO nanocrystals. Raman spectroscopy, X-ray photoelectron spectroscopy, photoluminescence measurement and electron spin resonance investigation clearly indicate that increasing the hydrothermal temperature results in the coexistence of SnO and SnO phases and the reduction of V concentration which are detrimental to the photocatalytic performance. Density functional theory calculations also reveal that the presence of V is responsible for the upshift of valence band maximum and an extended conduction band minimum, hence a valence band width broadening and band gap narrowing which consequently enhance the photocatalytic performance of the oxygen-deficient SnO.
氧空位（V）的引入被发现是改善二氧化锡晶体结构光催化性能的一种有效方法。本文采用简便的一步水热法，在低于以往报道的温度下成功制备了氧缺陷的二氧化锡（SnO）纳米晶体。还首次研究了水热温度对相组成和 V 含量的影响。由于其高氧空位浓度，在 80°C 下制备的 SnO 在紫外可见光下对甲基橙的光催化降解效果最佳。捕获剂捕获实验和硝基蓝四唑实验也表明，V 作为电子捕获位点和分子氧吸附位点，从而增加了活性 O 自由基的生成，而活性 O 自由基是控制 SnO 纳米晶体光催化活性的主要物质。拉曼光谱、X 射线光电子能谱、光致发光测量和电子自旋共振研究清楚地表明，提高水热温度会导致 SnO 和 SnO 相的共存以及 V 浓度的降低，这对光催化性能不利。密度泛函理论计算也表明，V 的存在导致价带顶的上移和导带底的扩展，从而拓宽了价带宽度并缩小了带隙，从而提高了氧缺陷 SnO 的光催化性能。
