Electrocatalytic oxygen evolution and photoswitching functions of tungsten-titanium binary oxide nanostructures

Abstract

Tungsten-titania (WO3-TiO2) based binary oxide was fabricated by an eco-friendly chemical route for electro-catalytic water splitting and photoelectrical applications. Ambiguous evidence for the coexistence of W/Ti oxides and their binary feature were extensively studied by different analytical tools and also affirmed using high-resolution microscopy. The existence of multiple defects in the binary material and their 2.68 eV optical band gap was evaluated using the room-temperature photoluminescence data and Tauc's plot, respectively. Nature of conductivity in WO3-TiO2 and its flat band potential was inferred using Mott-Schottky type electro-chemical impedance spectroscopic results. The enhanced photosensitivity in WO3-TiO2 was demonstrated using a flip-chip Schottky diode architecture and reasoned to the improved charge transfer kinetics across the same. Next, the potential of WO3-TiO2 for stable water splitting functions was examined. Here, WO3-TiO2 interface was found to provide an enriched surface area for effective charge transfer, complementing towards the effective oxygen evolution reaction (OER) performance. The results demonstrated a smaller overpotential of 270 mV, authenticating the oxide system as an effective anode material for water splitting reactions with excellent stability.