Development of a novel experimental DEMS set-up for electrocatalyst characterization under working conditions of high temperature polymer electrolyte fuel cells C. Niether a,⇑ , M.S. Rau a , C. Cremers a , D.J. Jones b , K. Pinkwart a , J. Tübke a a Fraunhofer-Institut für Chemische Technologie ICT, Joseph-von-Fraunhofer-Straße 7, 76327 Pfinztal, Germany b ICGM – UMR5253 – Agrégats, Interfaces et Matériaux pour l’Energie, Université Montpellier 2, 2 Place Eugène Bataillon – CC 1502, 34095 Montpellier cedex 5, France article info Article history: Received 20 October 2014 Received in revised form 31 March 2015 Accepted 1 April 2015 Available online 2 April 2015 Keywords: High temperature PEM fuel cell Differential electrochemical mass spectrometry Direct ethanol fuel cell abstract A new set-up for conducting differential electrochemical mass spectroscopy (DEMS) analysis at tempera- tures between 120 and 180 °C is presented. It enables the characterization and testing of model elec- trodes in a three electrode assembly under experimental conditions close to those in a high temperature proton exchange membrane fuel cell (HT-PEMFC). This is of special interest for the study of the degradation of fuel cell materials as well as the electro-oxidation reactions of small organic mole- cules used in direct alcohol fuel cells (DAFCs). While other DEMS set-ups only allow for studying reac- tions occurring in a liquid electrolyte, the HT-DEMS set-up makes it possible to study reactions in the gas phase. The design of the set-up is presented. Cyclic voltammetry (CV) measurements at 150 °C were carried out on Pt/C and Pt black catalysts under nitrogen atmosphere. Oxidation of adsorbed CO and bulk oxidation of ethanol were performed on Pt/C. Ó 2015 Elsevier B.V. All rights reserved. 1. Introduction The evolution of electrochemical power systems depends on the optimization of the electrodes and the electrolyte. Electrochemical devices transforming chemical energy into electric energy, such as fuel cells (FCs), can contribute to solving the present sustainable energy dilemma; because they are an efficient and clean alterna- tive to combustion engines for supplying electrical power for mobile applications [1]. An interesting type of fuel cell is the high-temperature proton exchange membrane fuel cell (HT- PEMFC) running at temperatures in the range of 120–200 °C [2– 6]. In comparison to fuel cells working at lower temperature their CO tolerance is improved dramatically [4] in particular above 160 °C, and the high temperature enhances the activity for the oxi- dation of small organic molecules such as methanol and ethanol [6–11]. Thus, HT-PEMFC technology is well suited for the develop- ment of direct alcohol fuel cells (DAFCs). In order to enable the improvement of the electrode materials, and therefore the performances of HT-PEMFCs, tools are required to allow the characterization and evaluation of the electrocatalytic activity of the electrodes under working conditions. The performance of the electrodes in a fuel cell depends on a combination of factors such as surface reactivity, electronic and ionic conductivity or facile mass transport of molecules [12,13], the latter being based on the architectural design of both elec- trodes in the cell [14]. In the case of DAFCs the selectivity of their anode electrocatalyst regarding different possible oxidation prod- ucts is a relevant factor concerning their performance and effi- ciency [15,16]. The coupling of electrochemical measurements with mass spec- trometry (MS) has been recognized as a powerful tool for the qual- itative and quantitative identification of products and intermediates involved in the mechanisms of diverse electro- chemical reactions. A key challenge is the coupling interface between the electrochemical cell and the mass spectrometer. The concept of the membrane introduction to conduct MS measure- ments (MIMS) was introduced by Hoch and Kok in the early 1960s [17]. Because of their rapid response time and low selectiv- ity [18] porous PTFE membranes are widely used for DEMS appli- cations. Using the flexibility of these membranes, the use of MS was adapted to different electrochemical applications [19–22]. Bruckenstein and Gadde [20], who collected gaseous electro- chemical reaction products in a vacuum system before detecting them by MS, were the first to implement this technique for the evaluation of electrochemical reactions. They placed a Teflon Ò (polytetrafluoroethylene, PTFE) membrane between the porous electrode and the mass spectrometer chamber so that volatile reac- tion products permeating through the membrane and could be ion- ized by electron impact (EI) without the interference of the solvent. http://dx.doi.org/10.1016/j.jelechem.2015.04.002 1572-6657/Ó 2015 Elsevier B.V. All rights reserved. ⇑ Corresponding author. E-mail address: christiane.niether@ict.frauhofer.de (C. Niether). Journal of Electroanalytical Chemistry 747 (2015) 97–103 Contents lists available at ScienceDirect Journal of Electroanalytical Chemistry journal homepage: www.elsevier.com/locate/jelechem