Photocatalytic activity of C, N and S doped SnO ₂ : effective band gap engineering to increase the quantum efficiency and exploration of the change in the position of Fermi energy with dopant concentration and its influence on photoreactiv

Abstract SnO 2 and Carbon (C), Nitrogen (N) and Sulphur (S) – doped SnO 2 (CNS@SnO 2 ) samples were synthesized via a hydrothermal and grinding method respectively. The thiourea was used as precursor for all the three dopant ions whose concentration was varied as 0.03 wt%, 0.06 wt% and 0.09 wt%. PXRD results confirm the replacement of high density oxygen atom by low density C and N atoms. UV–vis spectroscopy confirms the incorporation of C, N and S dopant ions by the shift in absorption edge towards visible region. The oxidation states of the dopant ions were confirmed as C 2− , N 3− and S 6+ by the X-ray photoelectron spectroscopic technique. The presence of N in the sample was also confirmed by FTIR technique. The optimum dopant concentration was found to be 0.06 wt% of thiourea. The higher value of photocurrent efficiency, photocurrent density and lower value of electrical energy per order confirms the efficiency of CNS@SnO 2 (0.06 wt%) sample due to the favourable function of Fermi energy (E F ) in the SnO 2 lattice.