Electrocatalysis on gold nanostructures: Is the {1 1 0} facet more active than the {1 1 1} facet? Ying Chen a , Wolfgang Schuhmann b , Achim Walter Hassel a,c, * a Max-Planck-Institut für Eisenforschung GmbH, Max-Planck Str. 1, D-40237 Düsseldorf, Germany b Analytische Chemie – Elektroanalytik & Sensorik, Ruhr-Universität Bochum, Universitätsstr. 150, D-44780 Bochum, Germany c Institute for Chemical Technology of Inorganic Materials, Johannes Kepler University, Altenbergerstr. 69, A-4040 Linz, Austria article info Article history: Received 22 July 2009 Received in revised form 25 August 2009 Accepted 25 August 2009 Available online 29 August 2009 Keywords: Anisotropic Nanobelts Nanoplates Glucose Methanol abstract The anisotropic electrocatalytic properties of gold nanobelts and nanoplates enclosed by either {1 1 0} or {1 1 1} facets were studied. Different strategies were used to synthesize these materials. It was found that the {1 1 0} surface of gold does not necessarily show a higher electrocatalytic activity than the {1 1 1} sur- face. The {1 1 0} surface of gold is more active than the {1 1 1} surface for glucose oxidation in both, neu- tral and alkaline media. However, for methanol oxidation in alkaline solution, the {1 1 0} surface shows a lower activity than the {1 1 1} surface, which is contrary to the general belief that {1 1 0} facet is the most active surface among the three basal planes. The possible mechanisms are discussed. Ó 2009 Elsevier B.V. All rights reserved. 1. Introduction The electrocatalytic properties of metal nanocrystals highly de- pend on the exposed surfaces. Experimental results as well as the- oretical considerations have emphasized the importance of the anisotropic properties of crystallographic planes [1,2]. Fundamen- tal studies of single crystal planes of noble metals, such as Au, Pd and Pt, demonstrated that the high-index planes possess a higher density of low coordination number step atoms in comparison with low-index planes such as {1 1 1}, {1 0 0}, and even {1 1 0} fac- ets, and exhibit high activity for breaking chemical bonds [2–6]. Thus, shape-controlled synthesis of metal nanocrystals bounded by high-index facets is deemed as a potential route for enhancing their catalytic properties [1,2,5–12]. Recently, Tian et al. reported that tetrahexahedral Pt nanoparticles bounded by {7 3 0}, {2 1 0} and/or {5 2 0} surfaces display an extraordinarily high catalytic activity [1]. Moreover, Liao et al. showed that Au star- and thorn- shaped nanoparticles enclosed by {3 3 1} and vicinal high-index facets show a higher electrocatalytic activity for H 2 O 2 reduction [5]. According to the fact that surface energies of different basal planes of fcc metals are in the order of c {1 1 1} < c {1 0 0} < c {1 1 0} [13], it is reasonable to assume that {1 1 0} surface should show the highest electrocatalytic abilities among the three low-index planes. The reports of the structurally and morphologically depen- dent electrocatalytic properties of nanocrystals are vast [1,2,5–14]. However, in most cases, nanocrystals with different exposed sur- faces have different shapes. This is because, generally, the final shape of nanocrystals is determined by exposed surfaces consider- ing the nature of the synthesis method [1,2,5–14]. Gold is known to form preferentially {1 1 1} surface with its low surface energy when being evaporated or sputtered onto a surface or when a bulk material is annealed [15]. Recently, a novel approach was estab- lished to prepare Au nanobelts and nanoplates enclosed by {1 1 0} surface, which is less common for gold [16–19]. These un- ique Au nanostructures, complemented with the traditional wet chemical method, enable to study the differences in properties of nanocrystals with similar shape but different crystallographic ter- mination. In this communication, gold nanobelts with {1 1 0} sur- face ({1 1 0} nanobelts) and nanoplates with either {1 1 0} or {1 1 1} surface ({1 1 0} nanoplates, {1 1 1} nanoplates) were used to study the anisotropic electrocatalytic properties by employing the electrooxidation of methanol and glucose as probe reactions. 2. Experimental Gold nanobelts and square-shaped nanoplates with {1 1 0} fac- ets were prepared through the combination of directional decom- position of the Fe–Au eutectoid alloy followed by a phase selective 1388-2481/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.elecom.2009.08.046 * Corresponding author. Address: Institute for Chemical Technology of Inorganic Materials, Johannes Kepler University, Altenbergerstr. 69, A-4040 Linz, Austria. Tel.: +49 211 6792; fax: +43 732 2468 8905. E-mail address: hassel@elchem.de (A.W. Hassel). Electrochemistry Communications 11 (2009) 2036–2039 Contents lists available at ScienceDirect Electrochemistry Communications journal homepage: www.elsevier.com/locate/elecom