Effect of adhesive layer on electron injection from plasmonic nanoparticles into titanium oxide under strong coupling condition

We fabricated titanium oxide electrodes with nanocavity functionality and supported gold nanoparticles on them to form a strong coupling between localized surface plasmon resonance (LSPR) mode of the gold nanoparticles and the nanocavity mode. This resulted in successful absorption of a broad range of visible wavelengths. When using the electrodes with modal strong coupling, we observed an increased internal quantum yield of photocurrent generation using water as an electron source compared to plasmonic electrodes without nanocavity. Furthermore, we elucidated that the mechanism behind this enhancement involves quantum coherent interactions of multiple LSPRs via the nanocavity. Here, we report the use of metallic titanium as an adhesion layer between the nanocavity and gold nanoparticles, leading to an increase in electron injection into titanium oxide and provide further insights into the underlying mechanism.