Photoelectrochemical studies of nonstoichiometric nanostructured PbOx using Fe(CN)6−4/−3 as an active electrolyte in ionic liquid

Abstract

Photoactive nanostructured lead oxide was prepared by applying DC potential pulse in alkaline sodium sulfate solution at 800C. The resulting oxide thin film showed vertically aligned interconnected nanowall assemblies all over the active substrate. The film was characterized by XRD, SEM, EDX and UV-vis diffuse reflectance spectroscopy. The UV-vis measurements confirmed an optical band gap of 1.95 and 2.71 eV, which can be attributed to the phases respectively α-PbO and β-PbO. Photoelectro chemical measurements under chopped white light illumination condition in ionic liquid (BMIm Cl−) medium showed a stable photoresponse extending to a wider potential range of 3.7 V compared to only 1.7 V in aqueous medium. Typical photocurrent densities of 3.01 and 4.03 mA/cm2 were obtained from ionic liquid and aqueous medium, respectively. The JV characteristic of a PEC cell indicates a low Voc of 273 mV in ionic liquid medium compared to 768 mV in aqueous medium. The low Voc is attributed to the shift of the redox potential of the active electrolyte in ionic liquid.