T. Honda et al., PH MEASUREMENT IN THE VICINITY OF A CATHODE EVOLVING HYDROGEN GAS-USING AN ANTIMONY MICROELECTRODE, Journal of Applied Electrochemistry, 28(6), 1998, pp. 617-622
An antimony microelectrode was prepared by quenching a molten Sb-Sb2O3
mixture (2% Sb2O3). The local pH in the vicinity of a cathode evolvin
g hydrogen gas was directly measured using the microelectrode. The loc
al pH during electrolysis of KCl-glycine aqueous solutions was increas
ed by proton consumption; however, the increment decreased with increa
sing concentrations of glycine, a buffering agent. The diffusion-limit
ing current density of hydrogen evolution involving proton reduction w
as controlled by the concentrations of the proton-donating species: pr
otonated-glycine (+HNCH2COOH)-N-3 and H3O+ ions. A plot of the current
density against the sum of the concentrations gives a single straight
line passing through the origin. The phenomena are discussed in terms
of electrodeposition processes of base metals.