Impact of Hot Carrier Dynamics on Photoelectrocatalytic Activity on Au@Pd Antenna-Reactor Nanoparticles
Hyewon Park, Seung‐Hyun Chun, Jeong Hoon Lee, Jihan Son, Sookyung Kim, Jungkweon Choi, Hyotcherl Ihee, Hyosun Lee, Jeong Young Park
Abstract
Photoinduced hot carriers generated from the decay of surface plasmons in noble metals play a decisive role in producing green hydrogen gas through the photoelectrochemical (PEC) water splitting reaction, a process driven by visible light absorption. To optimize the utilization of these hot carriers, we employed a plasmonic antenna-reactor model based on core–shell structured Au@Pd nanoparticles (NPs) with an ultrathin Pd shell. In this study, we demonstrate that TiO 2 nanotube arrays (TNAs) decorated with Au@Pd NPs exhibit superior performance with the Pd shell serving as a catalytic reactor that efficiently extracts hot carriers from the plasmonic Au antenna. The photocatalytic performance in PEC measurements increased with higher Pd coverage, and Au 70 @Pd 30 /TNAs exhibited a 2.2-fold higher photocurrent compared with bare Au/TNAs. The enhanced oxygen evolution reaction (OER) activity observed for Au 70 @Pd 30 /TNAs is attributed to the higher population of hot holes on the surface of Au@Pd NPs, which enhances the oxidation capability for interactions with electrolytes. Femtosecond transient absorption (fs-TA) spectra of Au@Pd NPs revealed a shorter lifetime of hot electrons through electron–phonon (e–p) scattering in Au 70 @Pd 30 NPs compared to Au NPs, indicating suppressed charge recombination and increased hot hole population on the surface. Therefore, this study suggests that the plasmonic antenna-reactor model, critically influenced by hot carrier dynamics, provides a promising framework for efficient photoelectrocatalytic systems.