Photocatalytic activity of ZnO nanoparticles synthesized from zinc nitrate and botanical extracts of neem, chrysanthemum, Mexican marigold and shiitake mushroom

Abstract Background Green synthesis emerges as a need to obtain functional materials, but this also involves following certain principles that imply methods and inputs that are friendlier to health and the environment. A wide variety of materials can be synthesized under these principles, one of them being ZnO, which can be used for environmental, electronic and biomedical applications to mention a few. In this work, ZnO nanoparticles (NPs) were synthesized using aqueous extracts of neem, chrysanthemum, Mexican marigold and shiitake mushroom and subsequently used to degrade methylene blue (MB) under solar light irradiation. The NPs were characterized by UV–visible spectroscopy, transmission electron microscopy, X‐ray diffraction, Fourier transform infrared spectroscopy and thermogravimetric analysis to investigate the structural, optical and electronic properties of the NPs. Results The results indicate the formation of hemispherical NPs with aggregates in a size range of 5.38–28.37 nm. All the samples presented a hexagonal wurtzite crystalline structure. The best photocatalytic performance for MB degradation was shown by ZnO NPs obtained using Mexican marigold (0.0873 ± 0.008 min −1 ) followed by those obtained using shiitake mushroom (0.0602 ± 0.002 min −1 ), neem (0.0365 ± 0.02 min −1 ) and chrysanthemum (0.0357 ± 0.01 min −1 ). Conclusions Botanical aqueous extracts have the potential to be used in the synthesis of semiconductor materials, as they allow the modification of the size and band gap. Many of the phytochemicals present in the extracts help to improve the interaction between catalyst and pollutants, in this case MB, and therefore have a positive impact on the degradation of textile pollutants. © 2022 Society of Chemical Industry (SCI).