Monodisperse Pt-Cu Nanocubes: Synthesis, Characterization, and Electrochemical Properties
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1217-Y01-04
Monodisperse Pt-Cu Nanocubes： Synthesis, Characterization, and Electrochemical Properties Dan Xu1, Hongzhou Yang2, Shouzhong Zou2 and Jiye Fang1,* 1 Department of Chemistry, State University of New York at Binghamton, Binghamton, New York 13902 2 Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056 ABSTRACT High-quality Pt-Cu nanocubes were prepared through simultaneous reduction of platinum (II) acetylacetonate and copper (П) acetylacetonate in 1-octadecene by 1,2–tetradecanediol in the presence of tetraoctylammonium bromide, oleylamine, and 1-dodecanethiol. The growth process of Pt-Cu nanocubes was explored based on the observation of intermediates. The electrocatalytic behavior indicates that cubic Pt-Cu nanocrystals are more active than spherical Pt-Cu nanocrystals and Pt nanocrystals towards methanol oxidation reaction. INTRODUCTION Platinum (Pt) nanoparticles (NPs) have been the subject of extensive studies because of their unique catalytic properties in various significant applications[1-5]. It has been realized that the catalytic activity of Pt NPs highly depends on the surface atomic arrangements on a particle.[6-8] For example, electrochemical evaluation on oxygen reduction reaction (ORR) in adsorbing acidic solutions indicates that Pt {100} are more active than Pt {111} planes [9, 10]. As electrocatalysts, nanocubes (NCbs) of Pt [11-13] therefore receive more interest than other morphologies such as multipod[14, 15] and one-dimensional nanostructure[16, 17]. In order to reduce the overall use of expensive Pt, Pt-based bimetallic nanocrystals (NCs) such as Pt-Ni[18, 19], Pt-Co[20-22], and Pt-Cu[23-25] have attracted an increasing interest as well. Moreover, recent reports indicate that electrocatalytic activities of some Pt-bimetallic NCs are superior to those of pure Pt metal[26, 27]. Therefore, it is highly worthwhile and significant to synthesize the Pt-bimetallic NCbs and to examine their electrocatalytic performance. To the best of our knowledge, however, there have been very few reports on preparation of Pt-bimetallic NCbs and examination of their electrocatalytic performances to date. In this paper, we report the studies on growth mechanism of Pt-Cu NCbs and comparison of the electrocatalytic activities towards methanol oxidation reaction among spherical Pt, Pt-Cu NPs and Pt-Cu NCbs. EXPERIMENT Synthesis of Pt-Cu nanocubes. The synthesis was carried out using a standard airless procedure. For a typical synthesis, 0.05 mmol of platinum (II) acetylacetonate [Pt(acac)2], 0.05 mmol of copper (II) acetylacetonate [Cu(acac)2], 0.5 mmol of 1,2–tetradecanediol (TDD) and 0.6 mmol of tetraoctylammonium bromide (TOAB) were mixed in 7.0 ml 1-octadecene (ODE). The mixture was then heated to 110 ºC with vigorous stirring followed by a subsequent injection of 1.6 ml of pre-prepared
oleylamine (OLA) in ODE (0.94 mmol for OLA) and 0.25 ml of pre-prepared 1-dodecanethiol (C12SH, DDT) in ODE (0.05 mmol for C12SH). The clear yellowish mixture was continually heated to 230 ºC and
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