CFTS-3/In2S3/SnO2:F heterojunction structure as eco-friendly photocatalytic candidate for removing organic pollutants

In this paper, quaternary chalcogenide Cu₂FeSnS₄ (CFTS) thin films were synthesized by spray pyrolysis using multilayer deposition technique in which the number (N) of sequential deposition runs (DR) is N = 1, 2, 3 and 4. The delivered volume in each sample is (N × 300 ml). Correspondingly, samples are named CFTS-N. Chemical composition, morphological, structural, optical and electrical properties were characterized using dispersive X-ray spectrometry (EDX), scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, spectrophotometer and Hall Effect measurements. XRD and Raman spectroscopy show a purer phase and better crystalline quality of CFTS-3 than other films. Average particle size increases with DR and reaches a maximum value of about 60 nm for N = 3. Optical results show high absorption coefficient value about 10⁵ cm^?1 in visible range, with an optical band gap of about 1.47 eV. Electrical resistivity of CFTS-3 equals to 5.82 10^?3 Ω cm which is the lowest value of these four samples. We have investigated the photocatalysis activity of various thin films by measuring the degradation of methylene blue (MB) and Rhodamine (RhB) as pollutant dyes. In particular we have compared the candidates: CFTS-3/SnO₂:F, CFTS-3/In₂S₃ and CFTS-3/In₂S₃/SnO₂:F. Under sun light irradiation, CFTS-3/In₂S₃/SnO₂:F heterojunction exhibits the best photodegradation rate (96%) of MB dye.