Mesoporous\nRE_0.5Ce_0.5O_2–<i>x</i> Fluorite\nElectrocatalysts for the Oxygen Evolution\nReaction

Abstract

Developing highly active and stable\nelectrocatalysts\nfor the oxygen\nevolution reaction (OER) is key to improving the efficiency and practical\napplication of various sustainable energy technologies including water\nelectrolysis, CO₂ reduction, and metal air batteries. Here,\nwe use evaporation-induced self-assembly (EISA) to synthesize highly\nporous fluorite nanocatalysts with a high surface area. In this study,\nwe demonstrate that a 50% rare-earth cation substitution for Ce in\nthe CeO₂ fluorite lattice improves the OER activity and\nstability by introducing oxygen vacancies into the host lattice, which\nresults in a decrease in the adsorption energy of the OH* intermediate\nin the OER. Among the binary fluorite compositions investigated, Nd₂Ce₂O₇ is shown to display the lowest\nOER overpotential of 243 mV, achieved at a current density of 10 mA\ncm^–2, and excellent cycling stability in an alkaline\nmedium. Importantly, we demonstrate that rare-earth oxide OER electrocatalysts\nwith high activity and stability can be achieved using the EISA synthesis\nroute without the incorporation of transition and noble metals.