Effect of solvent mixtures on the unique morphology for photocatalytic activity of Bi2S3 nanoparticles synthesized by microwave irradiation method

Abstract

Unique morphologies of Bi2S3 nanostructures were synthesized via microwave irradiation method using two different solvents [N,Ndimethylformamide (DMF) and ethylene glycol (EG)] and two solvent mixtures [N,N dimethylformamide/water (DMF/W) and ethylene glycol/water (EG/W)]. The effect of different solvent systems on the properties of Bi2S3 samples were investigated using XRD, FESEM, EDS, XPS, UV and FTIR analysis. The XRD analysis revealed that the orthorhombic phase of increasing intensities was observed. The microscopic analysis showed that the various shapes of Bi2S3 nanostructures were obtained by changing the solvent combinations. Long nanowires and nanorods with an average length of 250 nm formed when DMF and DMF/W were used as solvents. The synthesized Bi2S3 in EG and EG/W promoted the fabrication of novel nanoflowers composed of thick nanosheets with an average breadth of 755 nm and a honeycomb shape. The EDS and XPS results confirm the purity and the presence of the Bi and S. The N2 adsorption-desorption isotherm studies revealed that the specific surface area of the Bi2S3 sample (EG/W) is 42.82 m2g-1using Brunauer-Emmett-Teller (BET). The UV-Vis absorption spectra revealed the optical properties of all Bi2S3 samples. The FTIR spectra showed the functional groups of the Bi2S3 nanostructures. Among the prepared samples, the Bi2S3 nanostructure obtained in the ethylene glycol/water exhibited the highest photocatalytic activity and achieved 95.18% degradation efficiency of methylene blue (MB) dye after 120 minutes. The MB photodegradation was determined to follow a pseudo-first-order kinetic model, with a rate constant of 0.02271 min-1 being the highest. After three cycles, the Bi2S3(EG/W) nano photocatalyst showed excellent reusability and stability.