Observation of suppressed photocurrent of plasmonic Au on TiO2 by a double light beam method.

Decoration of TiO 2 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 TiO 2 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 TiO 2. 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. Image 1 • A double light beam method was proposed to study the enhanced photocurrent of Au. • Suppressed photocurrent of Au by inter-band transition of TiO 2 was observed. • Decreased generation of Au hot holes was attributed to the suppressed photocurrent. [ABSTRACT FROM AUTHOR]