Synthesis, Mössbauer study and catalytic properties of Cu-Ni-Fe- oxide/nitride mixed-phase materials

• Published in: Hyperfine interactions Vol. 242; no. 1
• Main Authors: Velinov, N., Petrova, T., Ivanova, R., Tsoncheva, T., Kovacheva, D., Eliyas, A., Mitov, I.
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.12.2021; Springer Nature B.V
• Subjects: 5-10 September 2021; Alizarin; Ammonia; Atomic; Brasov; Catalytic activity; Chemical synthesis; Citric acid; Condensed Matter Physics; Contaminants; Copper; Decomposition reactions; Hadrons; Heavy Ions; Iron; Light irradiation; Liquid nitrogen; Metal nitrates; Molecular; Mossbauer spectroscopy; Nickel; Nitrides; Nuclear Physics; Optical and Plasma Physics; Oxidation; Phase transitions; Physics; Physics and Astronomy; Proceedings of the International Conference on the Applications of the Mössbauer Effect (ICAME 2021); Quadrupoles; Romania; Selectivity; Sol-gel processes; Spectrum analysis; Structural analysis; Surfaces and Interfaces; Thin Films; X-ray diffraction; Methanol decomposition; iron-nickel nitrides; Photocatalytic water purification; Catalysis; Copper-nickel ferrites; Mössbauer spectroscopy
• ISSN: 0304-3843; 1572-9540
• DOI: 10.1007/s10751-021-01742-6

Materials with cation ratio Cu:Ni:Fe = 0.5:0.5:2 were prepared by sol-gel auto-combustion technique using corresponding metal nitrates and citric acid as complexating/fuel agent and ammonia for pH adjustment. For comparison, one sample was synthesised by the same method, but without pH adjustment, and one sample with nominal composition Cu 0.5 Ni 0.5 Fe 2 O 4 was synthesised by co-precipitation method. The methods of X-Ray Diffraction, Mössbauer spectroscopy at room (RT) and liquid nitrogen (LNT) temperature, UV-Vis, FTIR, nitrogen physisorption, and H 2 -TPR were applied for structural characterization of the materials. X-Ray Diffraction and Mössbauer spectroscopy proved formation of spinel phase, Fe 4-x Ni x N and minor quantity CuO phase. Presence of doublets with high quadrupole splitting (Δ = 1.02–1.07 mm/s) at RT Mössbauer spectra, which are partly preserved at LNT is evidenced that nitride phase has high nickel content. Specific surface of oxide/nitride samples was determined in the range 19–24 m 2 /g. The catalytic behaviour of the Cu-Ni-Fe- oxide/nitride materials is studied in reaction of methanol decomposition. Mössbauer spectra reveal significant phase transformations of the samples to Hägg carbide (χ-Fe 5 C 2 ) and Fe,Ni-alloy under the reaction medium, which ensures good catalytic activity and selectivity to H 2 and CO. The photocatalytic oxidation activity of samples was tested in degradation of Alizarin model contaminant dissolved in water under visible light and UV-C light irradiation.