Visible light degradation of textile effluent by electrodeposited multiphase CuInSe2 semiconductor photocatalysts

Abstract

Reduction in recombination of photogenerated electron-hole pairs and effective migration of the generated pairs across the surface of the photocatalyst to the aqueous solution of textile effluent can increase the photocatalytic efficiency of a semiconductor. In this study multiphase CuInSe2 (CIS) semiconductor with modified band gap was synthesized through pulsed electrodeposition (PED). Prepared photocatalysts were characterized by XRD, AFM, FESEM, TEM and UV–Vis DRS. The samples exhibited multiphase nature with prominently observed tetragonal and cubic crystallographic structures, having two different modified band gap energy. The photocatalytic degradation efficiency was investigated for the model dyes like methylene blue (MB), Rhodamine B (RhB) dye and the textile effluent under visible light irradiation. Successful degradation of the dyes and textile effluent were attributed to formation of heterojunction of the two phases with two different band gaps, with their energy band edges at the right positions, facilitating efficient migration of the photogenerated charge carriers across the surfaces, before their recombination. It motivates the initiation of chain of redox reactions and degrading reactions with the production of highly reactive hydroxyl radicals which attacked the dyes and the textile effluent. The photocatalytic degradation mechanism was proposed for the electrodeposited photocatalyst.