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Tin sulfide thin films, typically 350 nm thick, were deposited on SnO2:F -coated transparent conductive oxide glass substrates by pulse electrodeposition. The applied potentials were Von=−0.9V and Voff=0.1V vs saturated calomel electrode with pulse on/off durations of 10 s. The films crystallized in the orthorhombic structure corresponding to SnS (herzenbergite), with grain size varying in the range from a few nanometers to more than 100 nm. X-ray diffraction analysis shows an average size of 12 nm; however, scanning electron microscopy and transmission electron microscopy images show the presence of large crystallites with well-developed facets along with agglomerations of smaller crystallites. Estimation of the bandgap from the optical spectra of these films showed absorption due to direct transition occurring at 1.3 eV. Elemental compositions of these SnS samples determined using energy dispersive X-ray spectroscopy were 51.4 and 48.5%, respectively, for Sn and S. Raman spectra suggested the presence of traces of Sn2normalS3 and SnS2 . The surface analysis by X-ray photoelectron spectroscopy showed the presence of traces of metallic Sn. The films are photosensitive with a dark resistivity 106Ωcm .

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CuS nanoparticles (NPs) of few nanometers in size were prepared by a wet chemical method. The structural, compositional, and optical properties of the NPs were characterized by X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, micro Raman and Fourier transform infrared spectroscopy, N 2 adsorption-desorption isotherms, and UV-Vis diffuse reflectance spectroscopy. The XRD pattern proved the presence of hexagonal phase of CuS particles which was further supported by Raman spectrum. The estimated band gap energy of 2.05 eV for the slightly sulfur-rich CuS NPs is relatively larger than that of bulk CuS (1.85 eV), indicating the small size effect. As-prepared NPs showed excellent photocatalytic activity for the degradation of methylene blue (MB) under visible light. The surface-bound OH -ions at the CuS nanostructures help adsorb MB molecules facilitating their degradation process under visible light illumination. The studies presented in this paper suggest that the synthesized CuS NPs are promising, efficient, stable, and visible-light-sensitive photocatalyst for the remediation of wastewater polluted by chemically stable azo dyes such as MB.

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