Dynamic Analysis of Hot Carrier Driven Photocatalysis on Plasmonic Grating and Nanoantenna Photoelectrodes

We studied the hot carrier-driven photocatalysis on plasmonic gratings as well as nanoantenna photoelectrodes, mainly focusing on water splitting reactions. By varying the incident angles of p-polarized light (electric field is perpendicular to the grating lines), sharp troughs are observed in the reflectance spectra, which is originated from surface plasmon polaritons(SPPs). Photocurrent measured on Ag continuous film gratings is 44 times higher when light is p-polarized compared to s-polarized under 785 nm laser incidence under the bias of -0.5 V vs Ag/AgCl reference electrode. We also investigated the ultrafast dynamics of hot electron injection from Au nanoantenna photoelectrodes to water adsorbates by exciting localized surface plasmon resonance (LSPR). In situ ultrafast pump-probe transient absorption (TA) measurements are used to measure the hot electron injection dynamics, which shows a depletion peak is observed around the resonant wavelength. Finite Difference Time Domain (FDTD) simulations are carried out to study the electric field distribution near the surface of those photoelectrodes under resonant conditions, revealing various hot spots and different resonant modes.