Studies of Alcohol Oxidation on Pd-Electrodes in Alkaline Media

MECHANISTIC STUDIES OF ALCOHOL OXIDATION ON Pd-ELECTRODES IN ALKALINE MEDIA 

Itmumerable mechanistic studies of alcohol oxidation on Pt-based electrocatalysts in acidic media have been published over the last few years. Methanol, ethanol ° and ethylene glycol have been the most studied substrates and their oxidation paths on Pt or Pt alloys have been substantiated using a variety of in situ, extra situ and operando techniques as well as quantum mechanical calculations. The experimental techniques include reflection IR spectroscopy (IR), surface enhanced IR asbsorption spectroscopy (SEIRAS), attemrated total reflection-IR absorption spectroscopy (ATR-IRAS), differential electrochemical mass spectroscopy (DEMS), single potential alteration IR spectroscopy 

To the best of our knowledge, no Pt-based catalyst is able to promote the selective oxidation of ethanol to either CO2, acetic acid or acetaldehyde. However, the product composition can be modified by alloying Pt with other metals. For example, the addition of Sn to Pt increases the catalytic activity and also the production of acetic acid, while the addition of Ru improves the electrical performance without changing the product selectivity. Several authors have demonstrated that Ru and Sn are able to activate water al lower potential than pnre Pt, thus boosting the formation of CO2 and acetic acid, while Sn is particularly suited to reduce C-C bond breaking through a sort of dilution of adjacent Pt atoms.  

Unlike the relative abrmdance of mechanistic studies in acidic media, very few works dealing with alcohol electrooxidation on Pt-based systems in alkaline media have been published in the relevant literatirre, while studies involving Pd-based catalysts are virtrrally absent rmless one cortsiders some papers 

If DAFCs fuelled with ethanol and higher alcohols have a commercial future, this seems to be indissolubly linked to Pd-based electrocatalysts and anion-exchange membranes. As shown in this Chapter, the known catalytic architectures for alcohol oxidation are extremely valid, yet they suffer the scarce ability to cleave C-C bond in a selective way as well as poisoning by COads. Therefore increasing research efforts are required to design new catalysts with better performance and higher electrochemical stability. 

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