Efficient electrochemical CO2 reduction reaction on a robust perovskite type cathode with in-situ exsolved Fe-Ru alloy nanocatalysts

Abstract

Electrochemical carbon dioxide reduction reaction (CO2RR) via a solid oxide CO2 electrolyzer has been attracting increasing attention because it can effectively convert CO2 into high value-added chemical products and efficiently store the excessive electricity. However, the lack of efficient electrodes to catalyze this reaction process severely limits their practical applications. Herein, we report Ru promoted perovskite type Pr0.4Sr0.6Fe0.9Mo0.1O3-δ with a general formula of Pr0.4Sr0.6Fe0.8Ru0.1Mo0.1O3-δ (Ru-PSFM) cathode to overcome the constraints of low current density, low Faradaic efficiency, and high overpotential of CO2RR. The cathode electrolysis current density of CO2RR at 800 °C and 2.0 V is considerably improved from 0.707 to 1.480 A cm−2 with an enhancement rate of 109%, while its corresponding electrode polarization resistance at 1.4 V is significantly lowered from 2.228 to 0.319 Ω cm−2. Furthermore, the solid oxide CO2 electrolyzer exhibits superior stability during the operation. Distribution of relaxation times analysis results reveal that the rate-determining process, involving CO2 adsorption, dissociation, and activation on the cathode surface, is significantly activated and dramatically accelerated after Ru doping. Density function theory calculations demonstrate that the in-situ exsolved Fe-Ru alloy nanocatalyst is a more favorable site for the activation of CO2 dissociation. This work provides valuable insights into the rational design of efficient cathodes for CO2RR.