Electrochimica Acta 80 (2012) 377–382 Contents lists available at SciVerse ScienceDirect Electrochimica Acta jou rn al hom epa ge: www.elsevier.com/locate/electacta Electrooxidation of ethanol on PtSn nanoparticles in alkaline solution: Correlation between structure and catalytic properties Elena A. Baranova a,∗ , Monica A. Padilla b , Barr Halevi b , Tariq Amir a , Kateryna Artyushkova b , Plamen Atanassov b a Department of Chemical and Biological Engineering, University of Ottawa 161 Louis-Pasteur Ottawa ON K1 N 6N5, Canada b Chemical & Nuclear Engineering Department, University of New Mexico, Albuquerque NM 87131, United States a r t i c l e i n f o Article history: Received 22 June 2012 Received in revised form 11 July 2012 Accepted 11 July 2012 Available online 20 July 2012 Keywords: Ethanol electrooxidation Alkaline medium PtSn nanoparticles Catalyst structure a b s t r a c t Ethanol and carbon monoxide oxidation in alkaline media is investigated on a series of carbon-supported PtSn nanoparticles synthesized using a polyol reduction method. The PtSn electrocatalysts include two groups where one group is composed of disordered PtSn alloys and the other group composed of PtSn alloys intimately mixed with a SnO x phase. All catalysts were active during cyclic voltammetry exper- iments but the bi-phase PtSn + SnO x nanoparticles have significantly higher current densities at lower overpotentials compared to the pure alloy PtSn catalysts. During chronoamperommetry measurements all catalysts deactivated with time and only the bi-phase PtSnO x catalysts reached steady-state current densities after 3000 s with all others deactivating continuously. Catalyst bulk and surface structure were correlated with the observed electrochemical performance in alkaline media demonstrating that ethanol electrooxidation in 1 M KOH is more facile when electrocatalysst contain higher total amounts of both Pt and oxides. Alloying of Pt with Sn improves intrinsic, per Pt, catalytic activity and plausibly prevents Pt oxidation. Moreover, oxides decrease deactivation, possibly through improved CO or other intermediate adsorbate oxidation due to enhanced OH surface coverage. © 2012 Elsevier Ltd. All rights reserved. 1. Introduction An efficient ethanol electro-oxidation catalyst must support several distinct reaction processes: dehydrogenation, C C bond splitting, C oxidation, and CO oxidation. It has been shown that binary and ternary catalyst systems are needed to efficiently oxi- dize molecules such as methanol and ethanol [1–5] and that addition/alloying with Ru and Sn greatly enhance the per-Pt per- formance of catalysts. Pt-Sn catalysts are especially interesting since Sn is inexpensive and widely available. Pt–Sn alloys have therefore been previously studied and reported with many alcohol oxidation studies ascribing the observed performance of catalysts to idealized specific phases of PtSn. Thus PtSn alloys are clearly active for ethanol electro-oxidation, but phase-specific activity and structure-activity are not known because of generally limited cat- alyst characterization and the complex phase behavior of PtSn that includes several stoichiometric line compounds including Pt 3 Sn, Pt 7 Sn 3 , PtSn, Pt 2 Sn 3 , PtSn 2 , and PtSn 4 . [6] In this study we report ∗ Corresponding author. Tel.: +1 6135625800x6302; fax: +1 6135625172. E-mail addresses: elena.baranova@uottawa.ca, obaranov@uottawa.ca (E.A. Baranova). on PtSn nano-particles made by the polyol method [7] that are thoroughly characterized using XRD refinement, TEM, HRTEM, and XPS in an attempt to link the size and phase contribution of PtSn catalysts to ethanol electro-oxidation in alkaline media. 1.1. Acidic media A brief literature review of Pt with added Sn or Ru used for ethanol oxidation in acidic media finds that addition of Sn and Ru to Pt has been shown to enhance electrooxidation in general and of ethanol in particular. Several groups have confirmed the syn- ergistic effects of Sn and Ru addition to Pt, where both the metal ratio [8,9] and method of synthesis [1,10] have been found to influ- ence the observed catalyst performance in terms of both current and stability. In acid, PtSn oxidizes ethanol better than Pt and leads to complete oxidation to CO 2 [11–17]. The superior performance is attributed to a bi-functional mechanism where Pt decomposes the fuel, the addition of Sn reduces the adsorption strength of strongly adsorbed CO, and Sn or Sn-oxides provide surface oxygen or hydroxyls for enhanced oxidation [18]. While the method used to make the PtSn catalyst influences the optimal composition, in general 10–20 at.% Sn is reported to be optimal for co-impregnated catalysts [16]. 0013-4686/$ – see front matter © 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.electacta.2012.07.030