Chronopotentiometric Study of the Electrooxidation of Borohydride Anion in Alkaline Medium
Borohydrides present interesting options for electrochemical power generation acting either as hydrogen sources or anodic fuels for direct borohydride fuel cells and batteries. Though there have been several papers concerning electrochemical determination of relevant thermodynamic and kinetic parameters to the borohydride system, a number of its basic aspects have not been yet systematically studied. In this paper we report chronopotentiometric studies of the electrooxidation of sodium borohydride at a gold sphere electrode in 2M NaOH solutions, at temperatures ranging from 25 to 55 °C. Gold displayed a rather good BH4 - oxidation activity, and the overall oxidation process was shown to be irreversible involving a number of electrons very close to the theoretically expected value of 8. The results suggested that the rate-determining step is an irreversible, diffusion controlled, one-electron oxidation step, for which the transfer coefficients were calculated.
Prof. Andreas Öchsner and José Grácio
D. M.F. Santos and C. A.C. Sequeira, "Chronopotentiometric Study of the Electrooxidation of Borohydride Anion in Alkaline Medium", Defect and Diffusion Forum, Vols. 258-260, pp. 333-339, 2006