Redox-manipulated RhOx nanoclusters uniformly anchored on Sr2Fe1.45Rh0.05Mo0.5O6–δ perovskite for CO2 electrolysis

Abstract

The sluggish reaction kinetics of CO2 electroreduction in perovskite-based cathodes severely limits the efficiency of solid oxide electrolysis cells (SOECs). The construction of the high-density active sites on the perovskite surface is crucial for promoting CO2 electrolysis in SOEC. In this study, we explore a redox-induced redispersion strategy to produce RhOx nanoclusters uniformly anchored on a Sr2Fe1.45Rh0.05Mo0.5O6–δ (SFRhM) perovskite surface with a high density of 36,000 µm−2. Compared with non-uniformly distributed RhOx nanoparticles on Sr2Fe1.5Mo0.5O6–δ (RhOx/SFM) prepared by a conventional impregnation process, the successive reduction and oxidation treatment first exsolves the highly dispersed RhFe alloy nanoparticles on SFRhM and then selectively dissolves the iron species in the RhFe alloy nanoparticles into the bulk of SFRhM, resulting in fully exposed RhOx nanoclusters uniformly anchored on the SFRhM surface (RhOx@SFRhM). Electrochemical measurements and density functional theory calculations indicate that the high-density RhOx@SFRhM interfaces promote CO2 adsorption and activation during CO2 electrolysis, thus leading to improved electrocatalytic activity and stability compared to that of its SFRhM and RhOx/SFM counterparts.

Keywords

• Solid oxide electrolysis cell
• CO2 electrolysis
• Perovskite cathode
• In situ reductive exsolution
• Oxidative redispersion