Visible-light-active type-II heterojunction CdS@Cu0.5Mg2.5SnS4 composites for the efficient removal of brilliant green dye†

Copper magnesium tin sulfide (CMTS) is a multifunctional material that has recently generated a lot of interest as a potential new photocatalyst for organic pollutant degradation. Some of the desirable characteristics of CMTS are its narrow band gap energy, good chemical and photochemical stability, and high relative abundance of its constituent elements. In this work, CMTS (with the empirical formula Cu_0.5Mg_2.5SnS₄) and type-II heterojunction CdS@CMTS composites with varying CdS contents have been synthesized using a cost-effective and energy-efficient microwave-assisted method. X-ray diffraction analysis confirmed the presence of kesterite CMTS and hexagonal CdS in the composites. After the addition of CdS, the effective band gap energy of CMTS increased from 2.07 to 2.40 eV. The composites exhibited a uniform distribution of CdS on the CMTS surface. Photocatalytic studies reveal that CdS@CMTS exhibits higher photocatalytic activity for the degradation of brilliant green (BG) dye under visible light irradiation in comparison to pristine CMTS. Among the synthesized materials, the 30% CdS@CMTS exhibited the highest photocatalytic activity, with up to 95.8 ± 1.45% degradation of BG within 5 h. Thus, CdS@CMTS prepared by microwave-assisted synthesis has shown potential to degrade organic pollutants for wastewater remediation.