Real-time photothermal degradation of methylene blue dye by CuS thin film grown using a fully automated spray pyrolysis.

The real-time photothermal degradation of methylene blue (MB) dye was studied using CuS thin film (TF) as a photocatalyst. The polycrystalline CuS TFs were fabricated on precleaned glass substrates by an aqueous solution of copper chloride and thiourea using a fully automated spray pyrolysis technique by varying temperatures (250–400°C). The properties of deposited films were studied by XRD, SEM, UV–Vis–NIR spectroscopy, photoluminescence (PL) and Hall measurement. XRD results show that the CuS TFs crystallized in the cubic phase with an average crystallite size ~22–30 nm. CuS TF grown at higher temperatures (350°C, 400°C) exhibited very low strain of about 0.55 and 1%, respectively. Hall study revealed that films deposited at 400°C had good electrical parameters with mobility (μ) of 0.866 cm2 V−1 s−1, Carrier concentration (p) of 5.21 × 1019 cm−3 and conductivity (σ) of 49.4 Ω-cm−1. The estimated optical bandgap of films were found to be in the range of 2.10–2.26 eV, revealing blue shift due to quantum size effects. The PL spectra showed two characteristic bands of the CuS films, at 422 nm and an intense green band at 504 nm. The copper sulphide TF showed high photocatalytic activities in a photo-decolourization of MB dye under irradiation of visible light, as CuS TF was able to completely decompose the dye in 160 min. [ABSTRACT FROM AUTHOR]