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

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 Pr_0.4Sr_0.6Fe_0.9Mo_0.1O_3-δ with a general formula of Pr_0.4Sr_0.6Fe_0.8Ru_0.1Mo_0.1O_3-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. © 2022 Elsevier B.V.