Influence of W-doping on the optical and electrical properties of SnO2 towards photocatalytic detoxification and electrocatalytic water splitting

Abstract

Band gap tuning of nanomaterials is a current field of interest in order to transform UV-light active catalysts into visible light driven catalysts. Tungsten-doped SnO2 (W@SnO2) nanospheres (NS) with dopant concentration ranging from 0 to 6 mol%, were prepared and characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma optical emission spectrometry (ICP-OES) and UV-Visible spectroscopy. The UV-Vis spectroscopic results revealed the shifting of absorption edges of SnO2 to the visible portion of the spectrum, and the XRD peaks shifted to the lower 2θ values with increase of the tungsten contents from 0 to 6 mol%. These results were further supported by density functional theory (DFT) calculations. W@SnO2 NS were evaluated for photocatalytic degradation of crystal violet (CV) dye under the optimized experimental conditions. The liquid chromatography mass spectrometric (LCMS) analysis of the dye solution before and after degradation experiments demonstrated complete mineralization of dye probably to H2O and CO2. Moreover, the thin films of 6 mol% W@SnO2 catalyst were casted to make the photocatalyst simply reusable. The photocatalytic results when compared with Degussa-P25 (standard titania) under light irradiation (both in UV and Vis), showed that the use of thin film can be a preferred choice for visible light harvesting photocatalytic degradation. Furthermore, the synthesized materials were assessed for electrocatalytic water splitting, with an overpotential of 280 mV and 144 mV to execute the OER and HER respectively, in alkaline medium (l M KOH).