โ Scribed by D.B. Sepa; M.V. Vojnovic; Lj.M. Vracar; A. Damjanovic
No coin nor oath required. For personal study only.
Two diametrically different pH dependences have been reported for oxygen reduction at prereduced Pt electrodes. In the current density (cd) region with the Tafel slope of -2.3RT/F, the pH dependence expressed as dE/dpH is, according to one group of workers, -90 mV, ie -3 x 2.3 RT/(2F) and -30 mV, ie -2.3 RT/(ZF) in acid and alkaline solutions, respectively. The same dependences, according to another group of workers are -60 mV, ie -2.3 RT/F in both acid and alkaline solutions. In the cd region with the Tafel slope of -2 x 2.3RT/F, dE/dpH according to the first group of workers is -120 mV and 0 mV in acid and alkaline solutions, respectively. However, according to the second group, this dependence is -60 mV in both acid and alkaline solutions. The reasons for the variation in pH dependences is discussed. A previous analysis for the pH dependence of -2.3 RT/F at all pHs in both cd regions is in error. An account of the pH dependenees of -3 x 2.3 RT/(ZF) and -2.3 R T/(ZF) in terms of Temkin conditions of adsorption is satisfactory and allows for the change of Tafel slopes and pH dependences with increasing cd.
๐ SIMILAR VOLUMES