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

This report brings out the role of Au plasmons as the subjacent layer below TiO 2 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 300 o C for 20 minutes in the N 2 atmosphere. TiO 2 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 TiO 2 shows enhanced absorption (visible region) due to the plasmonic properties displayed by Au nanoparticles. TiO 2 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.