Properties of sol–gel SnO 2/TiO 2 electrodes and their photoelectrocatalytic activities under UV and visible light illumination

Abstract

A visible light active binary SnO 2–TiO 2 composite was successfully prepared by a sol–gel method and deposited on Ti sheet as a photoanode to degrade orange II dye. Titanium and SnO 2 can promote the development of rutile phase of TiO 2 and inhibit the formation of anatase phase of TiO 2. Formation of SnO 2 crystalline is insignificant even when the calcination temperature increases to 700 °C. Heterogenized interface between SnO 2 and TiO 2 inhibits growth of TiO 2 linkage and leads to the particle-filled surface morphology of SnO 2-containing films. The carbonaceous, Ti–O–C bonds and Ti 3+ species are likely to account for the photoabsorption and photoelectrocatalytic (PEC) activity under visible light illumination. The electrode with 30% SnO 2 exhibits higher photocurrent when compared with those in the region of 0–50%. The 600 °C-calcined SnO 2–TiO 2 electrode indicates higher activity when compared with those at 400, 500, 700 and 800 °C. PEC degradation of orange II follows the Langmuir–Hinshelwood model and takes place much effectively in a solution of pH 3.0 than those in pH 7.0 and pH 11.0.