Preparation and investigation of physiochemical, magnetic, and anti-microbial properties of cobalt-doped Bi2S3 nanostructure

The current study proposes the synthesis of cobalt-doped Bi2S3 nanostructures by the unique reverse micelle method at room temperature. Analysis using Energy dispersive analysis of X-rays (EDAX) demonstrated the correct stoichiometry, powder X-ray diffraction (PXRD) data were Rietveld refined using GSAS-II software confirming the formation of orthorhombic Bi2S3 with some residuals for cubic CoS2 phase. As the weight% of cobalt increases, the unit cell volume of orthorhombic Bi2S3 increases from 503.17 (16) (A0)3 to 507.34 (4) (A0)3. The Raman measurement shows the vibrational mode of both orthorhombic Bi2S3 and cubic CoS2 phases. The weak peak centered at 255 cm−1 is due to the symmetric vibration of the Bi–S bond which disappears in cobalt-doped samples and was replaced by new peaks related to Co–S bond vibration. This indicates the deformation in host orthorhombic Bi2S3 crystal due to cobalt doping and is consistent with Rietveld refinement results of PXRD. This work also gives the value of isobaric Gruneisen parameter for CoxBi2-xS3 (x = 0.0,1.0,1.5 & 2.0 wt%) were 5.1, −7.3, −4.8, and −5.2 respectively obtained from the low-temperature Raman measurement. The optical study shows the increment in band-gap with doping and proves to have visible light active band-gap. The pristine Bi2S3 nanostructures showed broad emission from the violet region (400 nm) to the yellow region (590 nm) with maximum emission at 440 nm in the blue region. The PL intensity decreases as cobalt weight% increases because of electron-hole recombination. The morphological study through high-resolution transmission electron microscopy (HR-TEM) revealed the single crystalline nature and showed the change in morphology from nanocylinders and nanorods with nanoparticles. The room temperature ferromagnetic behavior increases as cobalt weight% increases and reaches the maximum for 1.5 wt% cobalt. This study showed that the prepared nanostructures have potential application as an antimicrobial agent against both Gram + ve and Gram-ve microorganisms.