Department of Chemistry and Materials Engineering, Faculty of Chemistry, Materials and Bioengineering, Kansai University, Suita-shi, Osaka 564-8680, Japan.
Department of Pure and Applied Physics, The Faculty of Engineering Science, Kansai University, Suita-shi, Osaka 564-8680, Japan.
J Chem Phys. 2021 Sep 28;155(12):124702. doi: 10.1063/5.0055933.
The production of reactive oxygen species (ROS), such as hydroxyl radicals, by ultrasonic activation of semiconductor nanoparticles (NPs), including TiO, has excellent potential for use in sonodynamic therapy and for the sonocatalytic degradation of pollutants. However, TiO NPs have limitations including low yields of generated ROS that result from fast electron-hole recombination. In this study, we first investigated the sonocatalytic activity of TiO-supported Au nanoclusters (NCs) (Au NCs/TiO) by monitoring the production of hydroxyl radicals (•OH) under ultrasonication conditions. The deposition of Au NCs on TiO NPs was found to enhance sonocatalytic activity for •OH production by approximately a factor of 2. Electron-hole recombination in ultrasonically excited TiO NPs is suppressed by Au NCs acting as an electron trap; this charge separation resulted in enhanced •OH production. In contrast, the deposition of Au NCs on TiO NPs resulted in lower sonocatalytic activity due to less charge separation, which highlights the effectiveness of combining Au NCs with TiO NPs for enhancing sonocatalytic activity. The sonocatalytic action that forms electron-hole pairs on the Au/TiO catalyst is due to both heat and sonoluminescence from the implosive collapse of cavitation bubbles. Consequently, the ultrasonically excited Au (3 wt. %)/TiO catalyst exhibited higher catalytic activity for the production of •OH because of less light shadowing effect, in contrast to the lower catalytic activity when irradiated with only external light.
超声激活半导体纳米颗粒（如 TiO）产生的活性氧物质（ROS），如羟基自由基，在声动力学治疗和污染物的声催化降解方面具有很好的应用潜力。然而，TiO 纳米颗粒存在一些局限性，包括由于电子-空穴复合过快而导致产生的 ROS 产量低。在这项研究中，我们首先通过监测超声条件下羟基自由基（•OH）的产生来研究 TiO 负载金纳米团簇（Au NCs/TiO）的声催化活性。结果发现，Au NCs 在 TiO NPs 上的沉积可以将•OH 的产生的声催化活性提高约 2 倍。Au NCs 作为电子陷阱抑制了超声激发的 TiO NPs 中的电子-空穴复合；这种电荷分离导致了•OH 的产生增强。相比之下，由于电荷分离减少，Au NCs 在 TiO NPs 上的沉积导致声催化活性降低，这突出了将 Au NCs 与 TiO NPs 结合以增强声催化活性的有效性。在 Au/TiO 催化剂上形成电子-空穴对的声催化作用既源于空化泡的内爆压缩产生的热，也源于声致发光。因此，与仅受外部光照射时相比，超声激发的 3wt%Au/TiO 催化剂由于光阴影效应较小，因此具有更高的•OH 生成催化活性。
