Self assembled sulfur induced interconnected nanostructure TiO2 electrode for visible light photoresponse and photocatalytic application

Highlights: • Cost effective nebulizer spray route was adopted to prepare sulfur doped TiO₂ films. • Successful incorporation of sulfur in TiO₂ matrix confirmed from XPS analysis. • Enhanced photocurrent observed for sulfur doped films compared to pristine TiO₂. • Addition of sulfur improves the photocatalytic activity of TiO₂ under visible light. Pristine TiO₂ and sulfur doped TiO₂ (S-TiO₂) thin films were coated over the glass substrates by varying the concentration of sulfur source (thiourea – 2, 4, 6, 8 and 10 at%) using a cost-effective Jet nebulizer spray technique. The deposited thin films were in anatase phase with the tetragonal structure analyzed from the XRD pattern. The chemical state of the elements was determined from XPS analysis. Pristine TiO₂ and S-TiO₂ thin films depict the presence of spherical particles embedded over 3-D interconnected wire-like structure from SEM analysis. Optical studies revealed reduction in band gap of S-TiO₂ films on increasing the sulfur concentration (3.2–2.8 eV). The sulfur incorporation in TiO₂ lattice confirmed by the fall in intensity of near band edge emission as observed from room temperature PL spectra. The charge carrier dynamics of the prepared thin films were studied by means of steady state and transient photoconduction measurements. The photocatalytic performance of pristine TiO₂ and S-TiO₂ thin films for the degradation of malachite green dye was investigated under visible light.