Novel hybrid Cu2FeSnS4-ZnO hetero-structured nanocomposite for the photocatalytic degradation of malachite green

The photocatalysis research community is intensely focused on developing materials that offer a perfect blend of affordability, efficiency, and durability. Herein, novel hybrid Cu 2 FeSnS 4 -ZnO (CFTS-ZnO) hetero-structured nanocomposites in three different mass ratios and CFTS were designed by a microwave-assisted solvothermal method, while ZnO nanorods were synthesized via a hydrothermal method. The CFTS-ZnO (CFZN1, CFZN2 and CFZN3) nanocomposites, CFTS and ZnO were characterized for their crystal structure, surface morphology, and composition by XRD, HRSEM, TEM, and EDS, while UV–visible spectroscopy was employed to assess their optical properties and photocatalytic performance. XRD confirmed a tetragonal stannite crystal structure for CFTS, a hexagonal wurtzite crystal structure for ZnO and a mixture of hexagonal wurtzite and tetragonal stannite crystal structures for CFTS-ZnO (CFZN1, CFZN2 & CFZN3) nanocomposites. The average crystallite sizes were found to be 5.1, 54.9, 58.3, 51.3 and 56.4 nm for CFTS, ZnO, CFZN1, CFZN2 and CFZN3, respectively. Morphological analyses revealed nearly spherical morphology for CFTS, well-defined nanorods for ZnO, and uniformly anchored CFTS spheres onto the surfaces of well-defined ZnO nanorods for CFZN1, CFZN2 and CFZN3. The band gaps of CFTS, ZnONRs, CFZN1, CFZN2 and CFZN3 were found to be 1.47, 3.47, 2.51, 2.43 and 2.35 eV, respectively. The nanostructures were studied as photocatalysts for degrading malachite green (MG) dye under sunlight illumination. CFTS degraded about 54%, ZnONRs degraded about 51%, whereas CFZN1, CFZN2 and CFZN3 degraded about 47%, 58% and 98% of the initial MG dye within 120 min of exposure to sunlight. The photocatalytic degradation of MG proceeded via first-order kinetics, with rate constants (k) found to be 0.0071, 0.0060, 0.0048, 0.0067, and 0.0127 min − 1 for CFTS, ZnONRs, CFZN1, CFZN2 and CFZN3, respectively. The findings suggest that the nanomaterials, particularly the CFZN3 nanocomposites, are effective and economical photocatalysts for wastewater treatment, offering a promising solution for organic dye degradation.