Decoration of TiO₂ with plasmonic Au nanoparticles is attracting extensive research for enhancing photoelectrochemical water splitting efficiency. In this work, we propose a double light beam method to investigate enhance effect of Au nanoparticles on the TiO₂ single crystals. With double light beam method, it was found out that the photocurrent produced by Au nanoparticles was strongly decreased 3.5–4 times by inter-band transition of TiO₂. The amplitude of open circuit potential transient was decreased from 100 mV to 12 mV by the inter-band transition. By analysis with Mott-Schottky plotting, photo-generated Au hot hole concentration decreased from 1.28 × 10¹⁹ cm⁻³ to 1.02 × 10¹⁸ cm⁻³ was revealed. Potential independent photocurrent of Au NPs was observed, indicating that the photocurrent produced by Au NPs was determined by the generation rate of Au hot holes. The underlying reason for the suppressive effect of inter-band transition on the photocurrent of Au nanoparticles was pointed to the strongly decreased photo-generated Au hot hole concentration.

用等离子体Au纳米颗粒装饰TiO ₂吸引了广泛的研究以提高光电化学水分解效率。在这项工作中，我们提出了一种双光束方法来研究Au纳米颗粒对TiO ₂单晶的增强作用。用双光束法发现，通过TiO ₂的带间跃迁，Au纳米粒子产生的光电流大大降低了3.5–4倍。通过带间跃迁，开路电势瞬变的幅度从100 mV降低到12 mV。通过Mott-Schottky绘图分析，光生Au热空穴浓度从1.28×10 ¹⁹  cm ^-3降低到1.02×10 ¹⁸ cm ^-3显露出来。观察到Au NPs的电位独立光电流，表明Au NPs产生的光电流取决于Au热空穴的产生速率。带间跃迁对Au纳米粒子光电流的抑制作用的根本原因是由于光生Au热空穴浓度的大大降低。