Rapid degradation of perfluorooctane sulfonic acid (PFOS) and perfluorononanoic acid (PFNA) through bimetallic catalyst of Fe2O3/Mn2O3 and unravelling the effect of support SiO2

Perfluoroalkyl substances (PFAS) are emerging contaminants present in various water sources. Their bioaccumulation and potential toxicity necessitate proper treatment to ensure safe water quality. Although iron-based monometallic photocatalysts have been reported to exhibit rapid and efficient PFAS degradation, the impact of bimetallic photocatalysts is unknown. In addition, the mechanistic effects of utilizing a support are poorly understood and solely based on physicochemical properties. This study investigates the efficacy of bimetallic photocatalysts (Fe2O3/Mn2O3) in inducing the photo-Fenton reaction for the degradation of perfluorooctane sulfonate (PFOS) and perfluorononanoic acid (PFNA) under various conditions. The rapid removal of both PFAS was observed within 10 min, with a maximum efficiency exceeding 97 % for PFOS under UV exposure, aided by the photocatalytic activation (photo-Fenton) of the oxidant (H2O2). Contrary to expectations, the use of the SiO2 support material did not significantly improve the removal efficiency. The efficacy of PFNA decreased despite SiO2 providing larger surface areas for Fe2O3/Mn2O3 loading. Further analysis revealed that the adsorption of PFAS onto the catalyst surfaces owing to electrostatic interactions contributed to the removal efficiency, where the degradation efficacy was worse than that of the catalyst with SiO2. This is because adsorption hindered the effective contact of H2O2 with catalytic reaction sites, thereby impeding the generation of hydroxyl (·OH) radicals. This study indicates the importance of considering chemical properties, including surface charge, in catalyst design to ensure effective degradation, focusing on physicochemical properties, such as surface area might overlook crucial factors.

Hierarchical engineering of Mn2O3/carbon nanostructured electrodes for sensitive screening of acetylcholine in biological samples

Enzymeless electrochemical sensors have received considerable interest for the direct, sensitive, and selective monitoring of biomolecules in a complex biological environment.

A novel one-step synthesis of Ce/Mn/Fe mixed metal oxide nanocomposites for oxidative removal of hydrogen sulfide at room temperature

In this study, CeO₂/Fe₂O₃, CeO₂/Mn₂O₃, and CeO₂/Mn₂O₃/Fe₂O₃ nanocomposites were synthesized by the calcination of molten salt solutions. The microscopic images confirmed polyhedral nanocrystals of 10–20 nm size, clustered to form nanospheres. The elemental mapping confirmed the uniform distribution of transition metal oxides in the CeO₂ matrix. The X-ray diffraction analysis confirmed the phase purity of metal oxides in nanocomposites. The surface area of nanocomposites was in the range of 16–21 m² g⁻¹. X-ray photoelectron spectroscopy confirmed 25–28% of Ce³⁺ ions in the CeO₂ of nanocomposites. These nanocomposites were tested for the removal of hydrogen sulfide gas at room temperature. The maximum adsorption capacity of 28.3 mg g⁻¹ was recorded for CeO₂/Mn₂O₃/Fe₂O₃ with 500 ppm of H₂S gas and 0.2 L min⁻¹ of flow rate. The adsorption mechanism probed by X-ray photoelectron spectroscopy showed the presence of sulfate as the only species formed from the oxidation of H₂S, which was further confirmed by ion chromatography. Thus, the study reports room-temperature oxidation of H₂S over mixed metal composites, which were synthesized by a novel one-step approach.

In this study, CeO₂/Fe₂O₃, CeO₂/Mn₂O₃, and CeO₂/Mn₂O₃/Fe₂O₃ nanocomposites were synthesized by the calcination of molten salt solutions.

Porous hollow manganites with robust composite shells for oxidation of CO at low temperature

Hollow-type manganite-coated silica microspheres were synthesized via the thermal hydrolysis of urea. The Mn₂O₃/SiO₂_3T microspheres with robust shells exhibit best catalytic performance for CO oxidation even at temperatures below 200 °C.

Electrochemical energy storage in Mn2O3 porous nanobars derived from morphology-conserved transformation of benzenetricarboxylate-bridged metal–organic framework

MOF-derived Mn₂O₃ shows a high capacity of ∼410 mA h g⁻¹ as a 2 V anode and an ultrahigh energy density of 147.4 W h kg⁻¹ as a supercapacitor.