Hydrogen oxidation reaction exchange current density

Electrocatalytic Oxidation of Hydrogen The rate constant of the hydrogen oxidation reaction (HOR), as measured by the exchange current density jo (i.e. the current... 

Given that the rates of oxidation and reduction of the half-reactions are controlled by activation polarization only, that = 4-0.07 and = —0.08, and that the exchange current densities for both the oxidation of Fe and reduction of hydrogen in acidic solution are identical, use the data in Tables 3.3 and 3.4 to determine the following quantities. Recall that the potential for each half-cell is the sum of the equilibrium potential and the corresponding overpotential, in this case, r]a-... 

Electrode — Electrocatalytic electrode — Figure. Plots of the exchange current density of the hydrogen electrode reaction (left) as a function of the enthalpy of the metal-hydrogen bond and the current density of the electrochemical oxidation of ethylene as a function of the enthalpy of sublimation of various metals and alloys (right). These displays are also called Volcano plots... 

As discussed above, if the exchange current density of anode hydrogen oxidation is i nMc =0,1 Acni 2 and that of the cathode oxygen reduction reaction (ORR) is... 

The major dehciency of the oxygen electrode reaction is its low exchange current density (about 10 A/cm on a smooth surface) in acid electrolytes on even the best-known electrocatalyst (a platinum-chromium alloy). This value is about six orders of magnitude lower than that for the hydrogen electrode reaction in the same electrolyte. The reaction is about three orders of magnitude faster on smooth platinum or nickel oxide surfaces in an alkaline medium as compared to acid. The... 

This particular volcano plot is indeed nearly symmetric and demonstrates that Pt, Rh, Ir, and Re have the optimal M—H bond strength for maximum activity (exchange current density) for the hydrogen evolution/hydrogen oxidation reaction (HER/HOR). 

M HCIO4 for different disk electrodes as indicated in the labels, (bottom) Exchange-current densities in acid electrolyte (pH = 1) for the hydrogen oxidation reaction as a function of Pd coverage on the Pt( 111) substrate. 293 K. 

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