Can anybody please help me with the oxidation potentials (vs SHE) for CH3OH, CH2O and HCOOH? Thanking in advance and looking forward to the kind help!
Regards,
Fahad
The previous answers give values where oxidation may be observed; these are not thermodynamic quantities. We collected/calculated the electrode potentials ( = minus oxidation potential, be careful) and plotted them in a Frost diagram. See W. H. Koppenol and J. D. Rush, The reduction potential of the couple CO2/CO2.-. A comparison with other C1 radicals. J.Phys.Chem. 91:4429-4430, 1987. The pH is 7, but you can easily derive the standard electrode potentials.
The following information may be useful for your research
Free energy for closed intermediates are : CH3OH = 0.11 eV; CH2O = 0.71 eV; HCOOH = 0.20 eV at standard hydrogen electrode.
Ref: Reactivity descriptors for direct methanol fuel cell anode catalysts
Peter Ferrin ; Anand Udaykumar Nilekar; Jeff Greeley; Manos Mavrikakis;
,Jan Rossmeisl a,c; Surface Science 602 (2008) 3424–3431
dcwww.camd.dtu.dk/~jross/Welcome_files/Ferrin_SS_2008.pdf
The oxidation potential depents on the conditions of your system, f.e. the pH-value. Do you mean standart conditions?
usually, the oxidation potential of any molecule is based on the type of modification and the electrode materials. The methanol oxidation will come around +0.45-0.70 V vs SHE. Formic acid will oxidize about +0.5 V vs SHE. Formaldehyde oxidation will come around 0.3 to 0.7 V vs SHE.
The previous answers give values where oxidation may be observed; these are not thermodynamic quantities. We collected/calculated the electrode potentials ( = minus oxidation potential, be careful) and plotted them in a Frost diagram. See W. H. Koppenol and J. D. Rush, The reduction potential of the couple CO2/CO2.-. A comparison with other C1 radicals. J.Phys.Chem. 91:4429-4430, 1987. The pH is 7, but you can easily derive the standard electrode potentials.
Hi, Willem
Excellent answer! I'll keep in mind your ref. I would like to add that oxidation of alcohols, aldehydes commonly proceeds via a homolytic C-H bond cleavage. Therefore, the C-H bond dissociation energy (pH independent) is often more important than oxidation potential. In your work C-H bond cleavage is considered as PCET process.
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