Experimental and theoretical study on the reactivity of maghemite doped with Cu2+ in oxidation reactions: structural and thermodynamic properties towards a Fenton catalyst. Issue 84 (26th August 2016)

• Record Type: Journal Article
• Authors: Pires, Maíra dos Santos; Nogueira, Francisco G. E.; Torres, Juliana A.; Lacerda, Lívia C. T.; Corrêa, Silviana; Pereira, Márcio C.; Ramalho, Teodorico C.
• Is Part Of: RSC advances. Volume 6:Issue 84(2016)
• Page Start: 80830
• Page End: 80839
• Publication Date: 2016-08-26
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c6ra11032k
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : In this paper a new Fenton catalyst composed of iron oxide doped with a small amount of Cu was developed. Abstract : In this work, a polymeric method was used to prepare undoped and Cu-doped iron oxide catalysts for the H2 O2 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 Cu 2+ 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 Fe 3+ ions isomorphically replaced by 2 wt% Cu 2+ . Cu-doping produces an active catalyst for H2 O2 decomposition. Tests using phenol show the strong inhibition of H2 O2 decomposition by the Cu-doped catalysts, suggesting that H2 O2 may be decomposed via a radical mechanism. Furthermore, phenol degradation kinetics confirm that the doping of maghemite with Cu 2+ 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 H2 O2 and Cu 2+, thus improving the catalytic activity. This strategy can be extended to other materials to design active heterogeneous catalysts for environmental purposes.