Figure 5.

Photoelectrochemical HE characterization. (a) Schematic representation of the localized photoelectrochemical analysis system consisting of an electrolyte-filled (0.1 M Na₂SO₄) capillary with quasi-reference and counter electrode that touches the FTO/TiO₂/Ag_xAu_(1–x) sample, which is back-illuminated with a 532 nm laser. (b) Extracted external quantum efficiency (EQE) of hot electron injection into the electrolyte vs alloy composition. (c) Polarization-dependent photocurrent mapping that demonstrates a pronounced polarization effect at optimized compositions. (d) Schematic representation of the mechanism responsible for the observed polarization response: Plasmonic energy transfer from less reactive particle compositions to highly reactive compositions leads to enhanced yield if the light E-field is parallel to the gradient direction.