Role of Subjacent Plasmon Layer in Improving Photoelectrochemical Response of Metal Oxide Photoelectrodes

Abstract This report brings out the role of Au plasmons as the subjacent layer below TiO2 in PEC water splitting for hydrogen generation. Au was deposited on an ITO sheet using DC sputtering with 5 nm and 20 nm thickness and annealed at 300oC for 20 minutes in the N2 atmosphere. TiO2 in the form of the thin film was coated on the already deposited Au layer using a sol-gel spin coating method. Thin films were characterized using tools such as X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, and optical absorption spectroscopy. The presence of Au as the subjacent layer in TiO2 shows enhanced absorption (visible region) due to the plasmonic properties displayed by Au nanoparticles. TiO2 with subjacent Au layer (5 nm thickness) was found to exhibit eight times higher photoresponse than the pristine sample at 1.0 V/SCE which can be ascribed to the plasmonic effect of gold nanoparticles extending absorption in the visible region of sunlight.