Lattice Oxygen Redox Mechanisms in the Alkaline Oxygen Evolution Reaction

Abstract

Understanding of fundamental mechanism and kinetics of the oxygen evolution reaction (OER) is pivotal for designing efficient OER electrocatalysts owing to its key role in electrochemical energy conversion devices. In the past few years, the lattice oxygen oxidation mechanism (LOM) arising from the anodic redox chemistry has attracted significant attention as it involves a direct O─O coupling and thus bypasses thermodynamic limitations in the traditional adsorbate evolution mechanism (AEM). Transition metal‐based oxyhydroxides are generally acknowledged as the real catalytic phase in alkaline media. In particular, their low‐dimensional layered structures offer sufficient structural flexibility to trigger the LOM. Herein, a comprehensive overview is provided for recent advances in anion redox from LOM‐based electrocatalysts. Based on analyses of electronic structure of electrocatalysts and LOM, a strategy is proposed to activate LOM. Possible identification techniques for corroboration of the oxygen redox are also reviewed. In addition, the structural reconstruction process induced by the LOM is focused and the importance of multiple in situ/operando characterizations is highlighted to unveil the structural and chemical origins of the LOM. To conclude, a prospect on the remaining challenges and future opportunities for LOM electrocatalysts is presented.

Ultra-High Performance of In Situ Constructed Trimetallic (Pd, Fe, Co) Nanoparticles on Carbon Paper as an Electrocatalyst for Large Current Density Oxygen Evolution Reaction in Alkaline Seawater

“…The resulting oxygen vacancy sites are refilled by OH− and the surface is recovered (step 5). [37][38][39] The synthesized PdFeCo 1−x ONPs@CP catalyst exhibited Tafel slopes in the range of 20-120 mV dec −1 , suggesting that the ratecontrolling steps may be jointly determined by the first adsorption of OH − and O-H bond breakage (steps (I) and (II)). 20,[40][41][42][43][44] In addition, the smaller Tafel slope of the PdFeCo 1−x ONPs@CP catalyst suggests the promotion of the first adsorption of the OHand O-H bond breakage process due to the Pd and Fe dopants that modulate the electronic structure of the active sites, thus effectively ameliorating the OER catalytic kinetics and resulting in the best OER performance.…”