Superparamagnetic Fe3O4/In(OH)3 nanocomposite as a functional photocatalyst for the treatment of dyes and microbes under UVC

We report herein an improved method to produce a superparamagnetic Fe3O4/In(OH)3 nanocomposite (SPIDIN) at 25 °C in water by directly reducing FeCl3 with NaBH4 in the presence of In(OH)3 as heterogeneous seeds and non-toxic polyvinylpyrrolidone (PVP) as surfactant. The incorporation of Fe3O4 nanoparticles served to bestow SPIDIN's superparamagnetic properties which were confirmed in VSM analyses. Interestingly, the addition of Fe3+ led to the formation of In(OH)3 nanorods rather than the commonly observed nanocubes. In comparison to the In(OH)3 system having a band gap of 5.0 eV, two band gaps were observed for binary nanocomposite SPIDIN with one determined as 5.0 eV and the other as 2.8 eV via the use of Tauc's plot method. SPIDIN was characterized using a combination of PXRD, FESEM, HRTEM, EDS, Zeta Potential, UV-vis diffuse reflectance spectroscopy and FTIR analyses. Under UVC illumination, SPIDIN dispersed on carbon allowed synergistic photodegradation of methylene blue up to 95% within 1 hr. In the presence of H2O2, free standing SPIDIN was able to disinfect Gram-positive Staphylococcus aureus and Gram-negative Salmonella enterica, signifying the potential of SPIDIN in biomedical waste treatment with H2O being the innocuous byproduct.