Activation Energy Assessing Potential-Dependent Activities and Site Reconstruction for Oxygen Evolution

We demonstrated the activation energy approach to evaluate oxygen evolution performance and to probe active site reconstruction at different potentials. Activation energies are acquired following the Arrhenius equation by monitoring the current densities under varied hydroxide concentrations and temperatures. Our complex oxide electrocatalysts (Ag- and Ce-bidoped iron manganese oxyhydroxide) exhibit a much smaller activation energy of 19.12 kJ mol–1 in comparison to FeMnOH (60.01 kJ mol–1) at 1.7 V. The higher numbers of doped metal cations show smaller activation energy values corresponding to the higher activities, yet site reconstruction is less likely to occur. Through operando Raman studies, site reconstruction may not be absolutely required to reach a high-performance OER, in contrast to the general recognition. By knowing the potential-dependent activation energy, a quantitative OER activity comparison among reconstructed sites is possible. A substrate with a low background current is useful to experimentally acquire iR-corrected activation energies over a wide potential window.

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