Co-doping of Fe2O3 nanoparticles with Y and Zr by green synthesis

•Co-doping of Y and Zr into α-Fe2O3 lattice using one-pot green synthesis approach.•XRD, TEM, and Raman spectroscopy for identifying crystalline phase.•UV–vis data portrayed a lower bandgap for the room temperature sample.•No antibacterial action observed.•Photoreversible colour-switching catalytic property. The study aims to co-dope nanoparticles of iron oxide with yttrium and zirconium by one-pot green synthesis method using freshly plucked Simarouba Glauca (Paradise tree) leaf extract. The focus is on the effect of co-doping and also the effect of different annealing durations such as 2–4 h at a constant temperature of 600 °C. The nanoparticles were characterized using various techniques, such as Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD), Ultraviolet-visible Spectroscopy (UV–vis), Raman Spectroscopy, and Fourier Transform Infrared Spectroscopy (FT-IR). Antibacterial tests on Gram-positive and Gram-negative bacteria were performed to determine the bactericidal activity of the samples. The particle size was calculated to be around 55.95 nm through Bright Field-TEM (BF-TEM) images. XRD data confirms doping and indicates the formation of haematite phase with crystallite size increasing from 1.94 to 41.17 nm on increasing annealing duration and the phase was confirmed through HR-TEM data. Bandgap calculated through UV–vis data shows a decrease from 2.13 to 2.09 eV. Annealing duration had a notable effect on the crystallinity of the samples and their bandgap, but had no impact on their antibacterial properties. A unique result was observed in the degradation of methylene blue, where the reduced form of methylene blue undergoes a reversible change to reproduce methylene blue after a certain period. Liquid Chromatography Mass Spectrometry (LC-MS) was used to identify the intermediates and the products formed on catalysis. The result was a simultaneous reduction, oxidation and demethylation, as all three corresponding intermediates were formed. [Display omitted]