D. Konopka, Michael Errico, P. Bahrami
Oct 7, 2014
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Journal
Journal of Physical Chemistry C
Abstract
1,1,3,3-Tetramethylguanidine (TMG) is an organic superbase which has recently found use as a primary functional group in alkaline anion exchange membranes (AAEM). In this study we demonstrate the potential of aqueous TMG alkaline electrolyte as a substitute for NaOH(aq)/KOH(aq) with greater chemical similarity to AAEM functional groups. The water redox activities of Pt and Pd electrodes in 0.1 M TMG and 0.1 M KOH are compared, while hydrogen evolution/oxidation reactions (HER/HOR) and the oxygen reduction reaction (ORR) are studied in depth. Aqueous TMG supports comparable redox activity to KOH of equal concentration, but modifies surface processes through potential-dependent adsorptive behaviors. Rotating electrode, capacitance, and slow polarization measurements suggest that TMG and its decomposition species delay and participate in HER. HOR on Pt resembles that of a perfectly flat (111) surface in KOH, while hydrogen absorption on Pd is significantly hindered. ORR activity is dependent upon overpotenti...