Properties of sol–gel SnO2/TiO2 electrodes and their photoelectrocatalytic activities under UV and visible light illumination

A visible light active binary SnO2–TiO2 composite was successfully prepared by a sol–gel method and deposited on Ti sheet as a photoanode to degrade orange II dye. Titanium and SnO2 can promote the development of rutile phase of TiO2 and inhibit the formation of anatase phase of TiO2. Formation of SnO2 crystalline is insignificant even when the calcination temperature increases to 700 °C. Heterogenized interface between SnO2 and TiO2 inhibits growth of TiO2 linkage and leads to the particle-filled surface morphology of SnO2-containing films. The carbonaceous, Ti–O–C bonds and Ti3+ species are likely to account for the photoabsorption and photoelectrocatalytic (PEC) activity under visible light illumination. The electrode with 30% SnO2 exhibits higher photocurrent when compared with those in the region of 0–50%. The 600 °C-calcined SnO2–TiO2 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.