Differential mass electrochemical spectrometry

In situ analysis of the reaction products can also be carried out by mass spectrometry, using the differential electrochemical mass spectrometry (DBMS) technique.This technique permits the detection of gaseous products since they are produced and captured through a porous electrode. It has been confirmed that carbon dioxide is the main reaction product. With this technique, it is also possible to determine the production of CO2... 

Jusys Z, Behm RJ. 2001. Methanol oxidation on a carbon-supported Pt fuel cell catalyst—A kinetic and mechanistic study by differential electrochemical mass spectrometry. J Phys ChemB 105 10874-10883. 

Heinen M, Jusys Z, Behm RJ. 2009. Reaction pathways analysis and reaction intermediate detection via simultaneous differential electrochemical mass spectrometry (DBMS) and attenuated total reflection Bourier transform infrared spectroscopy (ATR-BTIRS). In Vielstich W, Gasteiger HA, Yokokawa H, eds. Handbook of Buel Cells. Volume 5 Advances in Electrocatalysis. Chichester John Wiley Sons, Ltd., in press. 

Jambunathan K, Jayataman S, HiUier AC. 2004. A multielectrode electrochemical and scanning differential electrochemical mass spectrometry study of methanol oxidation on electrodepos-ited PORUy. Langmuir 20 1856 1863. 

JusysZ. 1994. H/D substitution effect on formaldehyde oxidation rate at a copper anode in alkaline medium studied by differential electrochemical mass spectrometry. J Electroanal Chem 375 257-262. 

Recently the proposed Oz evolution mechanism was supported by the results of a DEMS (Differential Electrochemical Mass Spectrometry) study performed by Wohlfahrt-Mehrens and Heitbaum [71] on Ru electrodes. Using this mass spectroscopic technique and lsO labeling for the determination of reaction products during 02 evolution, it could be verified that the oxygen of the oxide formed on Ru takes part in the 02 evolution process. The same observation was made for Ru02 electrodes when using labeled H2lsO. 

N. Fujiwara, K. A. Friedrich, and U. Stimming, Ethanol oxidation on PtRu electrode studied by differential electrochemical mass spectrometry, J. Electroanal. Chem. 472, 120—125 (1999). 

Oxidation of thiourea adsorbed on Au(lll) and pc-Au electrode in 0.1 M HCIO4 has been investigated using CV, in situ Fourier transform infrared spectroscopy, and differential electrochemical mass spectrometry [165]. Two reaction mechanisms were proposed for the oxidation of the adsorbed and nonadsorbed thiourea. For both types of Au electrodes, similar results were obtained. 

Refs. [i] (1972) Definition, terminology and symbols in colloid and surface chemistry, Part I. Pure Appl Chem 51 77 [ii] Horanyi G (2002) Specific adsorption. State of art Present knowledge and understanding. In Bard AJ, Stratmann M, Gileadi M, Urbakh M (eds) Thermodynamics and electrified interfaces. Encyclopedia of electrochemistry, vol. 1. Wiley-VCH, Weinheim, pp 349-382 [Hi] Calvo EJ (1986) Fundamentals. The basics of electrode reactions. In Bamford CH, Compton RG (eds) Comprehensive chemical kinetics, vol. 26. Elsevier, Amsterdam, pp 1-78 [iv] Baltruschat H (1999) Differential electrochemical mass spectrometry as a tool for interfacial studies. In Wieckowski A (ed) Interfacial electrochemistry, theory, experiment, and applications. Marcel Dekker, New York, pp 577-597... 

Jusys, Z., Kaiser, J., and Behm, R.J., Simulated air bleed oxidation of adsorbed CO on carbon supported Pt. Part I. A differential electrochemical mass spectrometry study, J. Electroanal. Chem., 554/555, 427, 2003. 

We will first describe briefly the main experimental techniques coupled with electrochemical methods Infrared Reflectance Spectroscopy (IRS), Electrochemical Quartz Crystal Microbalance (EQCM), Differential Electrochemical Mass Spectrometry (DEMS), Chemical Radiotracers and High Performance Liquid Chromatography (HPLC). 

Differential Electrochemical Mass Spectrometry (OEMS) was also used for methanol stripping experiments, which can give some information on the electrode coverage by species coming from the adsorption and oxidation of methanol. First, it can be seen from the CVs and the MSCVs recorded on a coreduced PtogRuo2/C catalyst as an example (Fig. 19) that the coverage of the electrode is much lower from methanol adsorption (curves 2) than that from CO adsorption (curves 1). 

A quantitative study of the electro-oxidation of ethanol on carbon-supported Pt, PtRu and PtsSn catalysts was made by Behm and co-woikers " nsing combined voltarmnetric and on-line Differential Electrochemical Mass Spectrometry measnrements (DEMS). 

Finally, the combined voltammetric and on-line differential electrochemical mass spectrometry measnrements allow a quantitative approach of the ethanol oxidation reaction, giving the partial current efficiency for each product, the total number of exchanged electrons and the global product yields of the reaction. But, it is first necessary to elucidate the reaction mechanism in order to propose a coherent analysis of the DBMS results. In the example exposed previously, it is necessary to state on the reaction products in order to evaluate the data relative to acetic acid production which cannot be directly detected by DBMS measurements. However, experiments carried out at high ethanol concentration (0.5 mol L" ) confirmed the presence of the ethyl acetate ester characterized by the presence of fragments at m/z = 61, 73 and 88 at ratios typical of the ethyl acetate mass spectrum. " This ethyl acetate ester is formed by the following chemical reaction between the electrochemically formed acetic acid and ethanol (Bq. 29) and confirms the formation of acetic acid. 

Whether the oxidative or single nonoxidative desorption of the carbon monoxide occurs from the polycrystalline nickel surface was studied by differential electrochemical mass spectrometry (DEMS) [172] ... 

As shown in Fig. 4.3, a broad array of methods is available for this task. Direct identification of volatile molecular species present on or near an electrode is possible with differential electrochemical mass spectrometry (DBMS) [74-81]. For this method the electrode has to be porous and gas permeable. It is mounted on the inlet port of a mass spectrometer. Because of the pressure gradient between the vacuum and the electrochemical cell with the porous electrode operated at ambient pressure, volatile species can be sucked into the mass spectrometer and analysed therein. 

As a result, Wolter and Heitbaum obtained a mass signal proportional to the rate of the electrochemical reaction, i.e. to the current flowing through the porous electrode. Because of the applied pumping technique and because of the proportionality between electrochemical current (i.e. derivative of consumed charge) and mass signal, the method was called differential electrochemical mass spectrometry (DEMS)." ... 

H. Baltruschat, Differential electrochemical mass spectrometry. J. Am. Soe. Mass Spectrom. 15, 1693-1706 (2004)... 

S. Wasmus, S.R. Samms, R.F. Savinell, Multipurpose electrochemical mass spectrometry a new powerful extension of differential electrochemical mass spectrometry. J. Electrochem. Soc. 142, 1183-1189 (1995)... 

In Situ Differential Electrochemical Mass spectrometry (OEMS) [22]... 

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