Plasmonic photocatalysts provide means to efficient solar water splitting. Recently, researchers proposed that high-energy hot carriers generated by plasmon resonance can be transferred directly to the adsorbates, driving photochemistry, which differs from the previous indirect charge transfer forming electron-hole pairs. This study analysed underlying mechanism of charge transition channel in plasmon-driven photochemistry at the atomic scale, and evidence was provided for distinguishing between different modes of charge transfer. A specific example, where a cluster of six gold atoms interacts with one water molecule, was investigated. Based on combined density functional theory (DFT), Linear-Response time-dependent density functional (LR-TDDFT) and Ehrenfest dynamics simulations, the results revealed that hot electrons selectively transfer to high-energy unoccupied orbitals through indirect single-particle excitations or direct plasmon decay excitations. Direct transition was more conducive to photochemical reactions due to its higher energy.
Keywords Surface plasmon resonance, time-dependent density functional theory, charge transfer, Au cluster