Abstract
High-temperature CO(2) reduction to CO using perovskite-oxide-based solid oxide electrochemical cells holds promise for carbon-neutral chemical production, yet currently faces the challenge of coke formation that leads to device failure. A key reason behind this challenge is the absence of a correlation between the coke formation mechanism and perovskite structures. Here, lanthanum strontium cobalt ferrite perovskites are taken with a classical ABO(3) structure as examples to study coke formation on them and unravel the dependence of coke resistance on the Fe stoichiometry. Lowering the Co versus Fe ratio suppresses B-site metal exsolution, and thus, coke formation is catalyzed by these metals/alloys. Using (La(0.6)Sr(0.4))(0.95)Co(0.2)Fe(0.8)O(3-δ) as an example, this study reports an outlet CO pressure of 0.86 ± 0.02 atm at 800 °C, closely approaching the thermodynamic threshold for coking. The cell offers a stable outlet CO pressure of ≈0.8 atm in 320-h electrolysis at 220 mA cm(-2) and the potential to build a high-performance tandem system for efficient electrosynthesis of multi-carbon products from CO(2).