Electrochemical hydrogen evolution in hydroxide hydrate down to 110 K

Electrochemical hydrogen evolution was studied at an Au electrode in liquid and solid tetramethylammonium hydroxide hydrate (CH3),NOH . 10H(2)O (m.p. 253 K) down to almost 110 K. The current-potential relationships were obtai ned by slow scan voltammetry. The lowering of temperature causes substantia l decrease of the slope of linear Tafel plots. This was interpreted as a de crease of charge transfer coefficient from 0.37 at room temperature to 0.01 at 113 K. The activation energy of the electrochemical hydrogen evolution at temperatures below 200 K is equal to 0.25 +/- 0.03 eV and is larger than the activation energy of the electrolyte conductivity. (C) 2000 Elsevier S cience S.A. All rights reserved.