Abstract: This article describes an affordable method for the synthesis of MnMoO4 nanoflowers through the microwave synthesis approach. By manipulating the reaction parameters like solvent, pH, microwave power, and irradiation duration along this pathway, various nanostructures can be acquired. The synthesized nanoflowers were analyzed by using a powder X-ray diffractometer (XRD), field emission scanning electron microscopy (FE-SEM) with energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR), and UV-vis diffuse reflectance spectroscopy (UV-DRS) to determine their crystalline nature, morphological and functional group, and optical properties, respectively. X-ray photoelectron spectroscopy (XPS) was performed for the examination of elemental composition and chemical states by qualitative and quantitative analysis. The results of the investigations demonstrated that the MnMoO4 nanostructures with good crystallinity and distinct shape were formed successfully. The synthesized MnMoO4 nanoflowers were tested for their efficiency as a photocatalyst in the degradation studies of methylene blue (MB) as model organic contaminants in an aqueous medium under visible light, which showed their photocatalytic activity with a degradation of 85%. Through the band position calculations using the electronegative value of MnMoO4, the photocatalytic mechanism of the nanostructures was proposed. The results indicated that the effective charge separation, and transfer mechanisms, in addition to the flower-like shape, were responsible for the photocatalytic performance. The stability of the recovered photocatalyst was examined through its recyclability in the degradation of MB. Leveraging MnMoO4's photocatalytic properties, future studies may focus on scaling up these processes for practical and large-scale environmental remediation.

Abstract: The present study is related to the synthesis of metallic oxy halide nanosheets (FOX) assembled metallic micron-sponge (FOX-MS)-based photocatalytic materials using hydrothermal process to degrade tetracycline (TC) antibiotics. The synthesis of FOX-MS is accomplished by exchanging O- with I- that efficiently tunes the electronic structure (Fe3O4 or Fe2O3 to form FeOI) and band gap of FeOI. Interestingly, the band gap value decreases with increasing the reaction temperature from 120 to 180 degrees C attributed to the formation of stable FeOI due to maximum O- exchange with I-. Scanning electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy (FT-IR), and diffuse reflectance spectroscopy were used to characterize synthesized FOX-MS-based photocatalyst materials. Additionally, upon increasing the Fe metal amount (from 0.5 to 1 mM) during the synthesis the band gap decreases. However, further increment in the amount of Fe metal during synthesis increases the band gap value. The lower band gap value of similar to 1.82 eV with E-CB and E-VB value of 0.48 eV and 2.3 eV is in good agreement with the reported low band gap semiconductors for the degradation of various pollutants. The synthesized FOX-MS was efficiently degrading similar to 63% at 10 mgL(-1) of TC. Interestingly, Fenton activity of FOX-MS-based photocatalytic materials improved the TC degradation and achieved maximum degradation of similar to 94% at 10 mgL(-1) of TC antibiotics. The degradation of TC antibiotics was also performed under acidic and basic pH conditions to confirm the mechanistic pattern of degradation of TC using FeOI-based metallic microsponge. To the best of our knowledge, this is the first report of the synthesis of FeOI metallic microsponge using a hydrothermal process.