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Due to the ultra-high efficiency, environmental compatibility, structural/chemical stability, and effective usage of active metal centres, new single-atom catalysts, particularly single-atom carbon-based nano-photocatalysts, are promising "materials" for environmental remediations. Owing to their outstanding structure and features, like enormous activity, the selectivity, maximal atom usage, and improved intrinsic catalytic activity, single-atom catalyst has piqued researchers' interest. There is a wide class of carbon-based nanomaterials family which can be explored for the stabilization of single-atom catalysts. The carbon and carbon-based nanomaterials provide an excellent substrate for anchoring metal/metal oxide single-atom catalysts because of low-cost production, excellent conductivity, high surface area and functionality and tunable properties. The single-atom catalyst-based materials have found applications in electrocatalyis, hydrogen generation, carbon dioxide conversion and catalytic transformations. However, limited work has been done on utilizing carbon supported single-atom catalysts for high-performance removal/degradation of broad range of noxious organic and inorganic contaminants from water. Low coordination states, quantum size effects, and strong interactions with metals in nano-dimensions give them these features, which have proven to be particularly resilient in photocatalysis. In this paper, various methodologies for the manufacture of carbon-based single-atom catalysts are described. Then, in terms of comprehending the electrical and geometric properties of catalysts based on a single carbon atom, current developments in various characterization techniques and computer achievements were summarised. Meanwhile, aquatic pollution is being tackled using catalysts based on single carbon atom photocatalysts. The materials based on single-atom catalysts anchored/supported on to carbon materials based materials as carbon, carbon quantum dots, graphene, carbon nitride, etc. have been discussed. Finally, the prospects for their development, along with future prospects, are explored. Schematic illustration of synthesis techniques including their advantages, disadvantages and waste water remediation applications of nano-carbon matrix supported single-atom catalysts. [ABSTRACT FROM AUTHOR]

This work focuses on enhancing the photocatalytic activity of Co1−xZnxFe2O4 (cobalt-zinc nanoferrite) via peroxymonosulfate (PMS) activation for high-performance sulfosalicylic acid (SSA) degradation. The optimal Co0.7Zn0.3Fe2O4 (C2) sample led to the best photocatalytic performance for PMS activation under visible light. The photoluminescence and electrochemical impedance measurements confirmed the higher charge separation for C2 catalyst. The radical quenching and ESR tests revealed that SO4−• and •OH radicals were the dominant reactive species with little contribution from singlet oxygen for SSA degradation. The presence of Fe3+/Fe2+ and Co3+/Co2+ redox cycles enhanced the PMS activation to a great extent. Interestingly, the hydroxyl radicals were generated via the PMS activation route and contributed to degradation. As a result, photocatalysis and PMS activation complemented one another and improved performance. The best catalyst was also tested for the photocatalytic activity coupled with PMS activation for other pollutants including bisphenol A, tetracycline, rhodamine B, and 2,4-dichlorophenol. Additionally, due to their strong ferromagnetism and stability, the ferrites can be readily isolated magnetically from treated waste water, indicating their potential application in large-scale wastewater treatment for various contaminants. [ABSTRACT FROM AUTHOR]

In the present work, a series of Ni-doped La0.7Sr0.3FeO3 perovskite nanostructures with chemical composition La0.7Sr0.3Fe1−xNixO3 (x = 0.0, 0.01 and 0.04) were synthesized by the reverse micelle (RM) technique. The X-ray diffraction (XRD) analysis verifies good crystallinity and an orthorhombic crystal structure of the samples. The remarkable growth of the crystallites was observed in increasing the amount of Ni doping. The morphology, topography, and chemical composition were investigated through field emission scanning electron microscope (FESEM) equipped with an energy dispersive X-ray spectrometer (EDS). The FESEM/EDS measurements confirm uniform morphology and interconnected nature of the particles with relevant elements. The Fourier transform infrared (FTIR) spectra further demonstrate the perovskite structure through Fe/Ni–O asymmetric stretching and deformation of Fe/Ni–O–Fe/Ni bending vibrations in the lattice. A systematic reduction in the bandgap (Eg) is noticed upon the Ni doping in La0.7Sr0.3FeO3, as estimated from the UV/visible spectra by employing the Tauc's relation. A distinct behaviour of dielectric properties was revealed as a function of frequency and temperature for all the samples. The dielectric constant (ε′), dielectric loss (tanδ), and ac conductivity (σac) were measured at selected frequencies and temperatures. The results signify that the dielectric nature was frequency-dependent and thermally stimulated. The magnetic properties at room temperature indicate weak ferromagnetism with gradual increase in the maximum magnetization and coercivity with the increase in Ni concentration. [ABSTRACT FROM AUTHOR]