Ni–Fe–La(Sr)Fe(Mn)O₃ as a New Active Cermet Cathode for Intermediate‐Temperature CO₂ Electrolysis Using a LaGaO₃‐Based Electrolyte

Abstract

Various additives to Ni–Fe systems are studied as cermet cathodes for CO2 electrolysis (973–1173 K) using a La0.9Sr0.1Ga0.8Mg0.2O3 (LSGM) electrolyte, which is one of the most promising oxide‐ion conductors for intermediate‐temperature solid‐oxide electrolysis cells in terms of ionic‐transport number and conductivity. It is found that Ni–Fe–La0.6Sr0.4Fe0.8Mn0.2O3 (Ni–Fe–LSFM) exhibits a remarkable performance with a current density of 2.32 A cm−2 at 1.6 V and 1073 K. The cathodic overpotential is significantly decreased by mixing the LSFM powder with Ni–Fe, which is related to the increase in the number of reaction sites for CO2 reduction. For Ni–Fe–LSFM, much smaller particles (<200 nm) are sustained under CO2 electrolysis conditions at high temperatures than for Ni–Fe. X‐ray diffraction analysis suggests that the main phases of Ni–Fe–LSFM are Ni and LaFeO3; thus, the oxide phase of LaFeO3 is also maintained during CO2 electrolysis. Analysis of the gaseous products indicates that only CO is formed, and the rate of CO formation agrees well with that of a four‐electron reduction process, suggesting that the reduction of CO2 to CO proceeds selectively. It is also confirmed that almost no coke is deposited on the Ni–Fe–LSFM cathode after CO2 electrolysis.

Achieving High Efficiency and Eliminating Degradation in Solid Oxide Electrochemical Cells Using High Oxygen‐Capacity Perovskite

“…[8] However,t hese electrodes suffer from several important limitations,s uch as the redoxinstability and coarsening of Ni and the delamination and insufficient electrolytic performance of LSM during steam electrolysis. [9][10][11] LSM exhibits apparent oxygen excess non- stoichiometry in an oxidation environment. This excess oxygen in LSM gives rise to the formation of cation vacancies, which is thermodynamically unfavorable in the LaMnO 3 perovskite structure.…”

Preparation of La_0.9Sr_0.1Ga_0.8Mg_0.2O₃ Film by Pulse Laser Deposition (PLD) Method on Porous Ni–Fe Metal Substrate for CO₂ Electrolysis

“…A cermet cathode (Ni-Fe-(La,Sr)(Fe,Mn)O 3 ) was found the high activity to CO 2 electrolysis at elevated temperatures (973-1 173 K) on the cell using La 0.9 Sr 0.1 Ga 0.8 Mg 0.2 O 3 (LSGM) electrolyte. 11,12) Compared with Ni-Fe cathode in our previous work, 11,12) mixing (La,Sr)(Fe,Mn)O 3 with Ni-Fe improves the activity for CO 2 electro-conversion with much smaller overpotential loss. A current density of 2.32 A/cm − 2 at 1.6 V and 1 073 K was achieved for CO 2 electrolysis on the cell using the Ni-Fe-(La,Sr)(Fe,Mn)O 3 cermet cathode.…”

Achieving High Efficiency and Eliminating Degradation in Solid Oxide Electrochemical Cells Using High Oxygen‐Capacity Perovskite

“…Generally, state‐of‐the‐art SOECs use Ni‐YSZ (yttria‐stabilized zirconia) and LSM (strontium‐doped lanthanum manganites)‐YSZ as electrodes . However, these electrodes suffer from several important limitations, such as the redox‐instability and coarsening of Ni and the delamination and insufficient electrolytic performance of LSM during steam electrolysis . LSM exhibits apparent oxygen excess nonstoichiometry in an oxidation environment.…”