Structural, morphological, optical, magnetic and antimicrobial activity of charged surface acting agents (SAA) and growth regulator (GR)-assisted nanostructured Co3O4 particles via microwave-assisted precipitation method

Cobalt oxide (Co3O4) nanoparticles were synthesized using the different surface-acting agents (SAA) and growth
regulator (GR)-assisted microwave synthesis followed by precipitation process. The structural, morphological,
particle size, elemental composition, optical, magnetic and antimicrobial activities of the CTAB, SDBS and
ethylene glycol-assisted synthesized Co3O4 samples were examined using various analytical techniques. Powder
XRD patterns of the SAA-and GR-assisted Co3O4 samples revealed the face-centered cubic (FCC) crystal structure.
The FTIR spectra of the CTAB, SDBS and ethylene glycol-assisted Co3O4 samples showed two sharp bands at
~547 and 661 cm− 1 are ascribed to the Co–O vibrations. The morphological changes and particle size reduction
of the Co3O4 samples were effectively influenced by the SAA and GR through confirmed using the SEM studies.
EDX and XPS of the CTAB-assisted synthesized sample results showed cobalt oxide formation. The mesoporous
structure was confirmed through BET analysis. TEM analysis of CTAB-assisted Co3O4 sample confirmed the well
dispersed fine particles with average particle size range between 11 and 15 nm. The recorded light absorption
spectra of synthesized Co3O4 showed one absorption edge in the UV portion and another absorption edge in
visible region, which is ascribed to the O2− → Co2+, and O2− → Co3+ charge-transfer transitions, respectively.
The RT-PL emission spectra and chromaticity features of SAA and GR-assisted Co3O4 nanostructures were discussed in detail. Room temperature VSM analysis revealed that the synthesized CTAB-assisted Co3O4 sample
exhibits weak ferromagnetic behaviour. The antimicrobial activity of the Co3O4 sample was tested against the
Escherichia coli (Gram-negative), Streptococcus pneumoniae (Gram-positive), Pseudomonas aeruginosa (Gramnegative), Klebsiella pneumoniae (Gram-negative), and Candida albicans (fungal), using the well diffusion method
and their results presented in detail.