Paper Title
Photocatalytic Degradation of Methylene Blue using Cu2ZnSnS4 Nanoparticles Synthesized by SOL-GEL and Hydrothermal Methods

Abstract
Textile wastewater has been recognized as one of the roots that causes environmental problems. Nowadays photocatalysis, in which a photocatalyst absorbs a sunlight and degrades organic molecules, has attracted attention for degradation of organic pollutants in wastewater. Cu2ZnSnS4 (CZTS) is a semiconductor with high absorption coefficient which can be used as an efficient photocatalyst. CZTS nanoparticles can be prepared by several solution-based methods, however, a sol-gel method has never been used to synthesize CZTS photocatalyst for a photocatalysis process. In this study, two different methods of sol-gel and hydrothermal were used to synthesize CZTS nanoparticles and investigated for comparison. CZTS synthesized by hydrothermal method were of high crystallinity with crystallite size of about 23 nm. While CZTS synthesized by sol-gel method had crystallite size of about 5 nm. The photocatalytic activity of CZTS was examined to degrade methylene blue (MB) under visible light irradiation. 91.05% and 51.13% of MB was degraded after 15 h using CZTS nanoparticles synthesized by hydrothermal and sol-gel, respectively. To enhance the photocatalytic activity, hydrogen peroxide (H2O2) was also used with CZTS photocatalyst to generate more hydroxyl radicals for MB degradation. Keywords - Cu2ZnSnS4, Sol-gel, Hydrothermal, Photocatalysis, Photocatalytic degradation.