Use este identificador para citar ou linkar para este item: http://repositorio.ufla.br/jspui/handle/1/36948
Título: Experimental and theoretical study on the reactivity of maghemite doped with Cu2+ in oxidation reactions: structural and thermodynamic properties towards a Fenton catalyst
Palavras-chave: Cu-doped iron oxide catalysts
Maghemite doped
Catalisadores de óxido de ferro dopados com cobre
Magemita dopada
Editor: The Royal Society of Chemistry
Citação: PIRES, M. dos S. et al. Experimental and theoretical study on the reactivity of maghemite doped with Cu2+ in oxidation reactions: structural and thermodynamic properties towards a Fenton catalyst. RSC Advances, [S. l.], v. 6, n. 84, p. 80830-80839, 2016. DOI: 10.1039/C6RA11032K.
Resumo: In this work, a polymeric method was used to prepare undoped and Cu-doped iron oxide catalysts for the H2O2 decomposition reaction. These catalysts were characterized by powder X-ray diffractometry (XRD), scanning electronic microscopy (SEM) coupled to an energy dispersive X-ray spectrometer (EDX), and H2-Temperature Programmed Reduction (H2-TPR). The SEM images show an inhomogeneous particle cluster in both samples, tending to decrease in size with Cu-doping. EDX mapping reveals a good dispersion of Cu2+ in the iron oxide. In addition, Rietveld refinement of the XRD patterns reveals that the samples are constituted of hematite and maghemite, but only maghemite has octahedral Fe3+ ions isomorphically replaced by 2 wt% Cu2+. Cu-doping produces an active catalyst for H2O2 decomposition. Tests using phenol show the strong inhibition of H2O2 decomposition by the Cu-doped catalysts, suggesting that H2O2 may be decomposed via a radical mechanism. Furthermore, phenol degradation kinetics confirm that the doping of maghemite with Cu2+ brings about a significant improvement in catalytic activity. Theoretical calculations reveal that Cu-doping in maghemite produces low electronic density sites, favoring the interactions between the surface oxygens of H2O2 and Cu2+, thus improving the catalytic activity. This strategy can be extended to other materials to design active heterogeneous catalysts for environmental purposes.
URI: https://pubs.rsc.org/en/content/articlelanding/2016/ra/c6ra11032k#!divAbstract
http://repositorio.ufla.br/jspui/handle/1/36948
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