Synthesis and electrochemical characterization of Si/TiO2/Au composite anode: Efficient oxygen evolution and hydroxyl radicals generation

Highlights: • A novel composite anode composed of n-Si wafer/TiO₂/Au grid was prepared. • Electron/hole pairs can be thermally and photochemically generated in the Si. • Holes can migrate through the TiO₂ and onto the Au grid assisted by a bias voltage. • Aided by a bias voltage, oxygen evolution occurs at potentials lower than 1.23 V. • OH generation allows organics oxidation, water splitting, and electro-synthesis. -- Abstract: This paper describes the photoelectrochemical properties of a novel composite anode composed of a 200 nm Au-Sb ohmic contact/300 μm n-Si wafer/20 nm TiO₂ /120 nm Au grid. By connecting the Au ohmic contact to the gold grid via a power supply, holes thermally or photochemically generated in the Si are launched to the TiO₂ surface where they are converted to ^• OH radicals. We show that the Si/TiO₂/Au composite anode can be efficiently employed in the oxygen evolution reaction and prove that the anode generates hydroxyl radicals (using p-nitrosodimethylaniline as a probe). Potential applications include the photoelectrocatalytic oxidation of organic contaminants, water splitting, and organic electro-synthesis.