Highly carbonized tungsten trioxide thin films and their enhanced oxygen evolution related electrocatalytic functions

Abstract

Thin films of metal-oxide nanostructures based on tungsten (W) were established on silicon substrates for oxygen evolution reactions. The processed tungsten trioxide (WO3) thins films were carbonized at high temperature through methane treatment and studied extensively for their material properties. The carbonization effect on thin films were evaluated by diffraction, Raman, luminescence and scanning-electron microscopic studies. The influence of carbonization was also studied by X-ray photoelectron spectroscopy, where the effect of carbon species was quite conclusive. Carbonized and un-carbonized thin films were further collectively studied for their electrocatalytic potential by recording the electrochemical impedance and Mott–Schottky (MS) plots. Both the type of thin films were then subjected to oxygen evolution related electrocatalytic studies under alkaline pH (10 and 14) conditions. The enhanced conductivity studied in MS analysis in carbonized thin films were found to promote the oxygen production kinetics in respective electrode. This was affirmed through reduced overpotential values of 248 mV for carbonized thin films against 294 mV of un-carbonized ones. The Tafel slope values improved significantly in carbonized WO3 thin films. Finally, the stability related electrochemical results approved the processed films as viable electrocatalysts for effective oxygen evolution reactions.