Improved water splitting efficiency of Au-NP-loaded Ga(2)O(3) thin films in the visible region under strong coupling conditions

We fabricate a novel photoanode consisting of TiO(2)/Au nanoparticles (Au-NPs)/Ga(2)O(3)/TiN/Au-film (TAGA), efficiently increasing light absorption and electron transfer from Au-NPs to Ga(2)O(3) under modal strong coupling. A TiN thin layer deposited on an Au film enables stable high-temperature deposition of Ga(2)O(3) onto the reflective Au film mirror. Modal strong coupling is observed when the resonance wavelength of the Ga(2)O(3)/TiN/Au-film Fabry–Pérot cavity overlaps with the plasmon resonance wavelength of Au-NPs partially inlaid in a thin TiO(2) layer. Under strong coupling conditions, the light absorption and photoelectrochemical conversion efficiency in the visible region increased more than in the samples without coupling. In this structure, the TiO(2) layer partially inlaying Au-NPs plays a vital role in effectively enhancing the coupling strength. We accomplish water splitting at zero bias potential by taking advantage of the intrinsically negative conduction band potential of Ga(2)O(3).