Synthesis and properties of nanostructured Cr-doped hematite fibres
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ORIGINAL PAPER
Synthesis and properties of nanostructured Cr‑doped hematite fibres Marko Robić1 · Mira Ristić1 · Marijan Marciuš1 · Stjepko Krehula1 · Svetozar Musić1,2 Received: 26 February 2020 / Accepted: 7 June 2020 © Institute of Chemistry, Slovak Academy of Sciences 2020
Abstract Cr-doped α-Fe2O3 fibres were synthesized by combining electrospinning and the thermal treatment of electrospun composite fibres at 500 °C. XRD analysis showed the formation of solid solutions with a corresponding small decrease in the unit-cell volume due to a difference between the ionic radii of F e3+ and C r3+ cations. Mössbauer spectroscopy showed that the incor3+ poration of C r into the α-Fe2O3 crystal structure induced a decrease in the hyperfine magnetic field. Doping of α-Fe2O3 with Cr3+ also influenced the shape and position of IR bands in relation to reference α-Fe2O3 fibres in the corresponding FT-IR spectra. The FE-SEM images of Cr-doped α-Fe2O3 fibres showed that they consisted of interconnected nanoparticles and possessed a hollow substructure. The photocatalytic degradation of rhodamine B using electrospun fibres was also investigated. Keywords α-Fe2O3 · Cr-doping · Electrospinning · XRD · FE-SEM · Spectroscopy · Photocatalysis
Introduction Over the last decade, investigations related to hematite (α-Fe2O3) doping with different metal cations have been intensified. These investigations were mainly motivated by their potential for various applications. Generally, it is known that doping with metal cations may enhance a specific property of hematite, thus enabling a corresponding application of that material. Among many metal cations, chromium cation (Cr3+) is a convenient dopant owing to very similar ionic radii of Fe3+ (64.5 pm) and Cr3+ (61.5 pm) and because hematite and eskolaite (Cr2O3) are isostructural with corundum (α-Al2O3). Cr-doped hematites with an enhanced photoelectrochemical (PEC) activity were investigated (Kleiman-Schwarsctein et al. 2008; Shen et al. 2012; Bouhjar et al. 2018) for a possible use as photoanode in water splitting. Liu et al. (2019) prepared Cr-doped hematite using ball milling combined with the heat treatment of the resulting mixture. The authors
Mira Ristić: Deceased.
showed that 4 at.% Cr-doped hematite as electrode material significantly enhanced the reversibility capacity relative to undoped hematite in Li-ion batteries. It was also shown that Cr-doped hematite nanoparticles can be utilized as a highly selective and sensitive H 2S sensor at low temperatures (Xue et al. 2019). Ocwieja et al. (2017) tested Cr-doped hematite nanoparticles as a catalyst in the high-temperature water gas shift (HT-WGS) reaction. The properties of hematite doped with various metal cations depend both on the nature of the metal dopant and the synthesis method. Also, the morphology and size of doped hematite in the form of particles, fibres or films influence the material properties. In the present work, we report new results about doping of α-Fe2O3 with Cr3+ cations. The conditions for th
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