The Electrocatalysis of Oxygen Evolution on Perovskites

TLDR

Models indicate that the perovskite pores are active throughout and that rate‑determining steps involve OH radical desorption, consistent with electronic property correlations. Eighteen substituted perovskite oxides were tested for OER; rates at equilibrium and 0.3 V overpotential were reported, with kinetic parameters and roughness factors measured, showing that the rate is independent of semiconductor type but increases with alkaline pH, decreasing magnetic moment, lattice instability, lower enthalpy of formation of transition‑metal hydroxides, and higher d‑electron count, though roughness factor accuracy is limited by uncertain double‑layer capacitance.

Abstract

Measurements of the oxygen evolution reaction have been made on eighteen substituted perovskites containing first‐row transition metal ions. Rates are reported at equilibrium and at an overpotential of 0.3V. Electrode kinetic parameters are given, including roughness factors. The rate does not depend on semiconductor‐type properties. It increases as the pH of zero charge, at which the occupancy of OH− and H+ at the interface becomes equal, moves in an alkaline direction, with decrease of magnetic moment, with decrease of stability of the perovskite lattice, with decrease of the enthalpy of formation of the transition metal hydroxides, and with increase in the number of d‐electrons in the transition metal ion. The accuracy of the roughness factor measurements are affected by weakness in knowledge of true double layer capacities. The value assumed here, 60 μF cm−2, may be accurate to only ± 100%. Models are given which suggest that the pores are active throughout. The correlations between the rate and electronic properties are consistent with rate‐determining steps which involve desorption of OH radicals, e.g.,