Influence of stibnite thickness on the degradation of methylene blue in aqueous solutions under visible light

Abstract

In this work, we have investigated the physical, and photocatalytic properties of Sb₂S₃ thin films deposited on glass substrates by a dip-coating method as a function of their film thickness. The photocatalytic degradation of methylene blue (MB) dye under dark and visible light conditions for 60 min was used for the photocatalytic activity of Sb₂S₃ thin films. The champion photodegradation rate of 98.5% for MB under visible light conditions was obtained with a film thickness of 1200 nm. The surface morphology of stibnite films was studied by field emission scanning electron microscope (FESEM), demonstrating that the grain size increased as the film thickness increased. X-ray diffraction (XRD) analysis revealed the formation of a polycrystalline orthorhombic structure with a clear preferred orientation along the (221) plane. The formation of a single phase of stibnite thin films was corroborated by measuring Raman spectra, unveiling five major Raman peaks. The estimated optical band gap value decreases from 1.72 to 1.67 eV as the film thickness rises from 300 to 1500 nm, indicating the possibility of band gap tuning by changing the Sb₂S₃ film thickness. Electrochemical impedance spectroscopy (EIS) analysis has demonstrated the outstanding charge transfer properties of the stibnite thin films in the sample with a thickness of 1200 nm. These outcomes highlight the potential of film thickness for advanced photocatalytic applications.