Subject Area物理化学
Characterization of Novel Alumina-Supported PtFe Alloy Nanoparticles by Mossbauer Spectroscopy
Yin J(尹杰); Wang JH(王军虎); Zhang T(张涛); Tao Zhang; Junhu Wang
Conference NamePre-conference of ICC 14-Nanocatalysis: Fundamentals & Applications
Conference Date2008-7-9
Conference Place中国
Funding Organization中国科学院大连化学物理研究所
AbstractCHARACTERIZATION OF NOVEL ALUMINA-SUPPORTED PtFe ALLOY NANOPARTICLES BY MÖSSBAUER SPECTROSCOPY Jie Yin1,2, Junhu Wang1 and Tao Zhang1 1 State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian, 116023 China (e-mail: taozhang@dicp.ac.cn, wangjh@dicp.ac.cn) 2 Graduate School of Chinese Academy of Sciences, Beijing 100039 China Preferential carbon monoxide oxidation (PROX) is very important to supply hydrogen for fuel cells. Up to now, many kinds of catalyts have been reported to be active to the PROX reaction. Among of them, bimetallic nanoparticles (NPs) are proved to be the most promising candidate. Since the PROX reaction is very complicated, three kinds of architectures (core-shell, alloy and linked monometallic NPs) with different mechanisms have been proposed at least [1]. We are interested in characterizing the Mössbauer (MB) nuclide (Fe, Sn, Au, Ru, etc.)-containing bimetallic catalysts by MB spectroscopy and conversion electron MB spectroscopy under the ambient and working conditions of the catalysts, respectively. The aim is to shed new light on the mechanism investigation of the PROX reaction over the bimetallic NPs [2]. In the present work, three kinds of alumina-supported PtFe, PtFe2 and PtFe3 alloy NPs were prepared from Pt(acac)2, Fe(acac)3 and ethylene glycol in Ar atmosphere at 185oC. Their structural properties were investigated by XRD and 57Fe MB spectroscopy. The investigation of the catalytic activity and the product selectivity showed that the PtFex alloy NPs were more active for the PROX reaction under pretreatment both in H2 and in He at 400oC as compared to that of Pt/Al2O3 prepared by the same chemical route. As shown in Fig. 1, the XRD results indicated that the as-prepared PtFex NPs are chemically disordered face central cubic (fcc) structure and annealing at 600oC under N2 atmosphere induces the Pt and Fe atoms to rearrange into the long-range chemically ordered face central tetragonal (fct) structure. It was consistent with that reported so far and clearly revealed the as-prepared PtFex NPs were alloy. 57Fe MB spectra of the as-prepared PtFex/Al2O3 materials at room temperature are shown in Fig. 2. It revealed that there were several kinds of iron species contained in the materials, which were assigned as one PtFe alloy phase, one Fe3+ and one Fe2+ species. The MB results showed that the alumina-supported PtFe, PtFe2 and PtFe3 NPs were maintained in the alloyed state. Comparing with that of the PtFe alloy NPs, the ferrous component appeared in 57Fe MB spectra of alumina-supported Fe and PtFex alloy NPs. It implies that the strongly chemical interaction exists between NPs and support. In summary, the novel PtFex/Al2O3 nano-catalysts are different in the crystal structure and the oxidation state of iron as compared to the conventionally prepared one. These differences are reasonable to lead their catalytic performance and mechanism changed somewhat. References 1) S. Alayoglu, A. U. Nilekar, M. Mavrikakis and B. Eichhorn, Nature Mater. 7, 333 (2008). 2) J. Yin, J. Wang and T. Zhang, Catal. Lett., in revision.
Document Type会议论文
Corresponding AuthorTao Zhang; Junhu Wang
Recommended Citation
GB/T 7714
Yin J,Wang JH,Zhang T,et al. Characterization of Novel Alumina-Supported PtFe Alloy Nanoparticles by Mossbauer Spectroscopy[C],2008:134/1.
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