Combinations of semiconductor nanoparticles (NPs) with noble metal NPs enable an increase in the photoactivity of semiconductor NPs into the visible and near-infrared regions. The design rationale of the semiconductor-metal hybrid nanostructures for the optimization of charge carrier separation and reactive oxygen species (ROS) generation remains unclear. In this study, the interactions of Au nanorods (AuNRs) with TiO2 NPs were modulated by controlling their surface charges. Positively charged AuNRs formed aggregates with the negatively charged TiO2 NPs (AuNR@CTAB/TiO2) upon mixing, suggesting that Schottky junctions may exist between Au and TiO2. In contrast, negatively charged AuNRs (AuNR@PSS) remained spatially separated from the TiO2 NPs in the mixed suspension (AuNR@PSS/TiO2), owing to electrostatic repulsion. We used electron spin resonance (ESR) spectroscopy to detect the separation of charged carriers and ROS generation in these two mixtures under simulated sunlight irradiation. We also explored the role of dissolved oxygen in charge carrier separation and ROS generation by continuously introducing oxygen into the AuNR@CTAB/TiO2 suspension under simulated sunlight irradiation. Moreover, the generation of ROS by the AuNR@CTAB/TiO2 and AuNR@PSS/TiO2 mixtures were also examined under 808 nm laser irradiation. Our results show that the photogenerated electrons of excited semiconductor NPs are readily transferred to noble metal NPs simply by collisions, but the transfer of photogenerated hot electrons from excited AuNRs to TiO2 NPs is more stringent and requires the formation of Schottky junctions. In addition, the introduction of oxygen is an efficient way to enhance the photocatalytic activity of semiconductor NPs/noble metal NPs system combinations.

中文翻译：

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TiO2纳米粒子与不同涂层的金纳米棒在光照射下混合，分离电荷载流子并产生活性氧。

半导体纳米颗粒（NP）与贵金属NP的组合可提高半导体NP进入可见光和近红外区域的光活性。尚不清楚用于优化电荷载流子分离和活性氧（ROS）生成的半导体-金属杂化纳米结构的设计原理。在这项研究中，金纳米棒（AuNRs）与TiO2 NPs的相互作用是通过控制其表面电荷来调节的。带正电的AuNRs在混合时与带负电的TiO2 NPs（AuNR @ CTAB / TiO2）形成聚集体，表明Au和TiO2之间可能存在肖特基结。相反，由于静电排斥，带负电的AuNRs（AuNR @ PSS）在混合悬浮液（AuNR @ PSS / TiO2）中与TiO2 NPs在空间上保持分离。我们使用电子自旋共振（ESR）光谱来检测模拟阳光照射下这两种混合物中带电载流子的分离和ROS的产生。我们还通过在模拟阳光照射下将氧气连续引入AuNR @ CTAB / TiO2悬浮液中，探索了溶解氧在电荷载流子分离和ROS生成中的作用。此外，还研究了在808 nm激光照射下AuNR @ CTAB / TiO2和AuNR @ PSS / TiO2混合物产生ROS的情况。我们的结果表明，被激发的半导体NPs的光生电子很容易通过碰撞转移到贵金属NPs，但是光生热电子从激发的AuNRs到TiO2 NPs的转移更为严格，需要形成肖特基结。此外，