Enhanced Activity Promoted by CeOx on a CoOx Electrocatalyst for the Oxygen Evolution Reaction

Included among the many challenges regarding renewable energy technology are improved electrocatalysts for the oxygen evolution reaction (OER). In this study, we report a novel bifunctional electrocatalyst based on a highly dense CoOx catalyst by introducing CeOx. The CoOx catalyst is fabricated by two-step electrodeposition, including Co seed formation, to obtain a very dense, layered structure, and CeOx is also successfully deposited on the CoOx catalyst. CoOx is an active catalyst showing good activity (η = 0.331 V at 10 mA cm–2) and also stability for the OER. Higher activity is observed with the CeOx/CoOx electrocatalyst (η = 0.313 V at 10 mA cm–2). From mechanistic studies conducted with synchrotron-based photoemission electron spectroscopy and DFT calculations, Ce promotes a synergistic effect by perturbing the electronic structure of surface Co species (facile formation to CoOOH) on the CoOx catalyst and optimizes the binding energy of intermediate oxygenated adsorbates.