Hexakis(urea-O)iron Complex Salts as a Versatile Material Family: Overview of Their Properties and Applications

Béres, Kende Attila; Homonnay, Zoltán; Kótai, László

doi:10.1021/acsomega.3c09635

Cited by 4 publications

(1 citation statement)

References 112 publications

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“…Furthermore, the existence of a large number of isomorphic compounds among the possible precursors with other trivalent ions (Me III = Fe, Cr, Al) and MO )) mixed salts (where Y = S, Cr, etc.) [36,38,[75][76][77][78][79][80][81][82][83][84][85][86] gives enormous possibilities for adjusting the compositions and performances of new catalysts. The low cobalt and permanganatecontaining mixed crystals with "inert" cations (e.g., Al) and gas-forming anions (sulfate, perchlorate) ensure the in situ preparation of "supported" (e.g., with the co-formation of Al 2 O 3 support) Co-Mn oxide catalysts.…”

Section: Characterization Of the Solid Decomposition Productsmentioning

confidence: 99%

Insight into the Structure and Redox Chemistry of [Carbonatotetraamminecobalt(III)] Permanganate and Its Monohydrate as Co-Mn-Oxide Catalyst Precursors of the Fischer-Tropsch Synthesis

Béres,

Dürvanger,

Homonnay

et al. 2024

Inorganics

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[Carbonatotetraamminecobalt(III)] permanganate monohydrate was synthesized first in the metathesis reaction of [Co(NH3)4CO3]NO3 and NaMnO4 in aqueous solution. Its thermal dehydration at 100 °C resulted in phase-pure [Co(NH3)4CO3]MnO4 (compound 1). Compounds 1 and 2 (i.e., the hydrated form) were studied with IR, far-IR, and low-temperature Raman spectroscopies, and their vibrational modes were assigned. The lattice parameters were determined by powder X-ray diffraction (PXRD) and single crystal X-ray diffraction (SXRD) methods for the triclinic and orthorhombic compounds 1 and 2, respectively. The detailed structure of compound 2 was determined, and the role of hydrogen bonds in the structural motifs was clarified. UV studies on compounds 1 and 2 showed the distortion of the octahedral geometry of the complex cation during dehydration because of the partial loss of the hydrogen bonds between the crystal water and the ligands of the complex cation. The thermal decomposition consists of a solid phase quasi-intramolecular redox reaction between the ammonia ligands and permanganate anions with the formation of ammonia oxidation products (H2O, NO, N2O, and CO2). The solid phase reaction product is amorphous cobalt manganese oxide containing ammonium, carbonate (and nitrate) anions. The temperature-controlled thermal decomposition of compound 2 in toluene at 110 °C showed that one of the decomposition intermediates is ammonium nitrate. The decomposition intermediates are transformed into Co1.5Mn1.5O4 spinel with MnCo2O4 structure upon further heating. Solid compound 2 gave the spinel at 500 °C both in an inert and air atmosphere, whereas the sample pre-treated in toluene at 110 °C without and with the removal of ammonium nitrate by aqueous washing, gave the spinel already at 300 and 400 °C, respectively. The molten NH4NO3 is a medium to start spinel crystallization, but its decomposition stops further crystal growth of the spinel phase. By this procedure, the particle size of the spinel product as low as ~4.0 nm could be achieved for the treatments at 300 and 400 °C, and it increased only to 5.7 nm at 500 °C. The nano-sized mixed cobalt manganese oxides are potential candidates as Fischer-Tropsch catalysts.

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Section: Characterization Of the Solid Decomposition Productsmentioning

confidence: 99%

Insight into the Structure and Redox Chemistry of [Carbonatotetraamminecobalt(III)] Permanganate and Its Monohydrate as Co-Mn-Oxide Catalyst Precursors of the Fischer-Tropsch Synthesis

Béres,

Dürvanger,

Homonnay

et al. 2024

Inorganics

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CoFe₂O₄@N‐CNH as Bifunctional Hybrid Catalysts for Rechargeable Zinc‐Air Batteries

Yadav,

Deckenbach,

Yadav

et al. 2024

Adv Materials Inter

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Improving the efficiency of bifunctional electrocatalysts is a decisive challenge in the area of long‐lasting rechargeable zinc‐air batteries. Enhancing the catalysts' performance is crucial for advancing zinc‐air batteries. Transition‐metal oxides have emerged as promising non‐precious, noble‐metal‐free catalysts. Herein, a unique precursor directed approach is introduced for preparing a cobalt ferrite@nitrogen doped carbon nanohorns (CoFe2O4@N‐CNHs) nanohybrid catalyst in a single step annealing process involving stoichiometric amounts of single‐source cobalt and iron molecular precursors and carbon nanohorns (CNHs) under an argon/ammonia (Ar/NH3) atmosphere. This procedure enables a simultaneous CoFe2O4 ferrite synthesis and nitrogen functionalization of CNHs. The precious metal free nanohybrid CoFe2O4@N‐CNHs‐30% containing 30% of carbon presents an oxygen reduction reaction (ORR) half wave potential and onset potential comparable to the standard ORR catalyst 20% Pt/C. CoFe2O4@N‐CNHs‐30% also establishes superior oxygen evolution reaction (OER) performance with a low overpotential and a small Tafel slope than benchmark OER catalyst RuO2. Furthermore, the rechargeable zinc‐air battery with the CoFe2O4@N‐CNHs‐30% nanohybrid as air electrode demonstrates steadier and more durable charge–discharge cycles, and outstanding energy density relative to the state‐of‐the‐art 20% Pt/C‐RuO2 catalyst.

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Unusual relaxation phenomena in the 57Fe Mössbauer spectra of FeX3 (X = Cl, NO3, ClO4, MnO4, 1/2(S2O8)) complex salts containing urea, methylated urea, chlorido or aquo ligands: studies on the influence of the ligand sphere and deuteration

Béres,

Kótai,

Kuzmann

et al. 2024

J Radioanal Nucl Chem

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Mössbauer spectra of FeIII complex salts with urea-related ligands show a broadened line due to magnetic relaxation. The origin of the relaxation is not known, mostly spin–spin type is considered. A study of a large number of compounds can be helpful to show differences in the Mössbauer parameters and to see the infuence of the chemical environment on the relaxation. We have evaluated the Mössbauer spectra of 13 compounds recorded at various temperatures with the Blume–Tjon two-state relaxation model and with the (unrestricted) Afanasev–Gorobchenko model. The latter showed significant differences between some salts, and proved the presence of spin–lattice relaxation. Graphical abstract

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Hexakis(urea-O)iron Complex Salts as a Versatile Material Family: Overview of Their Properties and Applications

Cited by 4 publications

References 112 publications

Insight into the Structure and Redox Chemistry of [Carbonatotetraamminecobalt(III)] Permanganate and Its Monohydrate as Co-Mn-Oxide Catalyst Precursors of the Fischer-Tropsch Synthesis

Insight into the Structure and Redox Chemistry of [Carbonatotetraamminecobalt(III)] Permanganate and Its Monohydrate as Co-Mn-Oxide Catalyst Precursors of the Fischer-Tropsch Synthesis

CoFe₂O₄@N‐CNH as Bifunctional Hybrid Catalysts for Rechargeable Zinc‐Air Batteries

Unusual relaxation phenomena in the 57Fe Mössbauer spectra of FeX3 (X = Cl, NO3, ClO4, MnO4, 1/2(S2O8)) complex salts containing urea, methylated urea, chlorido or aquo ligands: studies on the influence of the ligand sphere and deuteration

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Hexakis(urea-O)iron Complex Salts as a Versatile Material Family: Overview of Their Properties and Applications

Cited by 4 publications

References 112 publications

Insight into the Structure and Redox Chemistry of [Carbonatotetraamminecobalt(III)] Permanganate and Its Monohydrate as Co-Mn-Oxide Catalyst Precursors of the Fischer-Tropsch Synthesis

Insight into the Structure and Redox Chemistry of [Carbonatotetraamminecobalt(III)] Permanganate and Its Monohydrate as Co-Mn-Oxide Catalyst Precursors of the Fischer-Tropsch Synthesis

CoFe2O4@N‐CNH as Bifunctional Hybrid Catalysts for Rechargeable Zinc‐Air Batteries

Unusual relaxation phenomena in the 57Fe Mössbauer spectra of FeX3 (X = Cl, NO3, ClO4, MnO4, 1/2(S2O8)) complex salts containing urea, methylated urea, chlorido or aquo ligands: studies on the influence of the ligand sphere and deuteration

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CoFe₂O₄@N‐CNH as Bifunctional Hybrid Catalysts for Rechargeable Zinc‐Air Batteries