Plasmonic hot carrier-driven photoelectrochemical water splitting on antenna–reactor Pt/Ag/TiO₂ Schottky nanodiodes

Plasmonic photoelectrochemical (PEC) water splitting has excited immense interest, as it can overcome the intrinsic limitations of semiconductors, in terms of light absorption, by the localized-surface plasmon resonances effect. Here, to get insight into the role of plasmonic hot carriers in plasmonic water splitting, a rational design of an antenna–reactor type Pt/Ag/TiO₂ metal–semiconductor Schottky nanodiode was fabricated and used as a photoanode. Using the designed PEC cell system combined with the Pt/Ag/TiO₂ nanodiode, we show that the plasmonic hot carriers excited from Ag were utilized for the oxygen (O₂) evolution reaction and, consequently, had a decisive role in the enhancement of the photocatalytic efficiency. These results were supported by finite-difference time-domain simulations, and the faradaic efficiency was measured by the amount of actual gas produced. Therefore, this study provides a deep understanding of the dynamics and mechanisms of plasmonic hot carriers in plasmonic-assisted PEC water splitting.