Cyclic voltammetry as a tool for characterization of supported VIII group metal catalysts Anton V. Tokarev a,b , Leonid M. Kustov b , Ari Ivaska a , Dmitry Yu. Murzin a, * a Process Chemistry Centre, A ˚ bo Akademi University, FIN-20500 Turku/A ˚ bo, Finland b Department of Chemistry, Moscow State University, 119992 Moscow, Russia Received 23 February 2006; received in revised form 21 April 2006; accepted 21 April 2006 Available online 12 June 2006 Abstract Possibility of the cyclic voltammetry (CV) in characterization of supported VIII group metal catalysts was studied. The emphasis was laid on Pd catalysts. A standard procedure for CV measurements was proposed and validated. Reasons causing cumbersome behavior of copper under- potential deposition (UPD) were revealed. The relative surface areas of metal catalysts on conductive and non-conductive supports were measured. # 2006 Elsevier B.V. All rights reserved. Keywords: Cyclic voltammetry; Supported catalysts; Characterization; Surface area determination; Conductive and non-conductive supports 1. Introduction Rapid advances in the field of catalysis with more demanding requirements for catalyst performance in terms of activity and selectivity, call for versatile characterization of catalytic materials. Time and costs of analysis can be a bottleneck, hindering successful development of heterogeneous supported metal catalysts, which in particular requires accurate measurements of the crystallite size (and consequently their exposed surface areas and dispersion) of these nanomaterials. High resolution TEM recently emerged as a valuable tool to the already existing arsenal of more traditional techniques, e.g. hydrogen or CO chemisorption and XRD to name a few. Some of these methods are not readily available and tedious and they are relatively expensive thus restricted to a small number of samples. The work reported in this paper is a step to develop a reliable method for fast and inexpensive routine analysis needed for every day catalytic research. The method can also be used as a complimentary to other methods. To this end the possibility to use cyclic voltammetry (CV) to characterize supported (also on non-conductive supports) metal catalysts will be verified. Cyclic voltammetry is a reversal technique and is the potential-scan equivalent of double potential step chronoamperometry. The symmetrical triangular wave scan is used to sweep the potential with time. The applied signal is a voltage ramp with sweep rates ranging from ca. 1 mV/s to about 1000 V/s. In such measurements, it is customary to record the current as a function of potential, which is equivalent to record the current as a function of time. Cyclic voltammetry is a popular technique in electrochemical studies in general and especially to obtain information about the kinetics and mechanism of electrode reactions [1]. Cyclic voltammetry is also used in analysis of metal electrodes, electrodes for fuel cells [2] and characterization of electroconductive polymers [3] to name a few. However, this technique is rarely used in catalyst characterization, with the exception of fuel cells, where the catalyst itself is the electrode. The majority of heterogeneous catalysts applied in everyday research and applications are powdered materials that cannot directly be used in electro- chemical measurements. By using composite electrodes where the catalyst is mixed with a binder and graphite it is possible to make electrochemical characterization for a wide range of materials like carbons [4], minerals [5] and metals placed on conductive and non-conductive supports [6–8]. All the mentioned papers show that it in principle is possible by electrochemical methods to characterize multiple combinations of platinum metals and supporting materials. The purpose of the present study is thus to develop a common electrochemical method to characterize all VIII group www.elsevier.com/locate/apcata Applied Catalysis A: General 309 (2006) 52–61 * Corresponding author. Tel.: +358 2 215 4985; fax: +358 2 215 4479. E-mail address: dmurzin@abo.fi (D.Yu. Murzin). 0926-860X/$ – see front matter # 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.apcata.2006.04.038