Mixed-Conductor Sr₂Fe_1.5Mo_0.5O_6−δ as Robust Fuel Electrode for Pure CO₂ Reduction in Solid Oxide Electrolysis Cell

Abstract

Electrolysis of carbon dioxide to carbon monoxide, through which the greenhouse gas could be effectively utilized, using solid oxide electrolysis cells is now attracting much interest. Here, we show for the first time that the redox-stable Sr 2 Fe 1.5 Mo 0.5 O 6−δ (SFM) ceramic electronic-ionic conductor can be used as the electrocatalyst to electrolyze and convert 100% CO 2 to CO without using any safe gases like H 2 and CO. SFM maintained its cubic structure and had an electrical conductivity of 21.39 S cm −1 at 800 °C in 1:1 CO−CO 2 atmosphere. Its surface reaction coefficient for CO 2 reduction is 7.15 × 10 −5 cm s −1 at 800 °C. Compared with those reported for the typical oxide ceramic electrodes, high electrochemical performance has been demonstrated for single phase SFM cathode using 100% CO 2 as the feeding gas. For example, a current density of 0.71 A•cm −2 was obtained using a fuel cell supported on LSGM (La 0.9 Sr 0.1 Ga 0.8 Mg 0.2 O 3−δ ) electrolyte operated at 800 °C and an applied voltage of 1.5 V. The electrolysis performance was further improved by using SFM−Sm 0.2 Ce 0.8 O 2−δ composite cathode, and the current density increased to 1.09 A•cm −2 under the same operation conditions. Durability test at 800 °C for 100 h demonstrated a relatively stable performance for CO 2 electrolysis under harsh conditions of 100% CO 2 without safe gas and above 1 A cm −2 current density, which is seldom achieved in the literature but highly desirable for the commercial application, indicating that SFM is a highly promising ceramic fuel electrode for CO 2 electrolysis.

Sr2Fe1.4Mn0.1Mo0.5O6−δ perovskite cathode for highly efficient CO2 electrolysis

“…Many mixed-conducting perovskite-type oxides have been tested for use as cathode for CO 2 electrolysis such as La 0.75 Sr 0.25 Cr 0.5 Mn 0.5 O 3 (LSCM), [6][7][8] La x Sr 1Àx TiO 3Àd (LST), [9][10][11] La 0.8 Sr 0.2 FeO 3Àd (LSF), 12 and Sr 2 Fe 1.5 Mo 0.5 O 6Àd (SFM). [13][14][15] Amongst these, the iron-based materials LSF and SFM are reported to exhibit the highest electrocatalytic activity for CO 2 reduction in the intermediate to high temperature range (600-850 C).…”

“…Isomorphic substitution of A-or B-sites by other types of cations is a known strategy to optimize the performance of perovskite oxide electrodes. [16][17][18][19][20][21][22][23][24][25] In previous research, [13][14][15] we showed that the double perovskite SFM is a promising electrode material for pure CO 2 electrolysis. Aiming at further promoting the rate of CO 2 reduction at the SFM surface, we have investigated in this work the inuence of partial substitution of Fe in SFM by Mn (to produce Sr 2 Fe 1.4 Mn 0.1 Mo 0.5 O 6Àd (SFMM0.1)) on its effectiveness as a cathode material for CO 2 electrolysis.…”

Direct Electrolysis of CO2 in a Symmetrical Solid Oxide Electrolysis Cell with Spinel MnCo2O4 as Electrode

“…[12][13][14] Even though, carbon deposition is still unavoidable in Ni-YSZ cathode. [17][18][19] Compared to the traditional SOEC, symmetrical cell configuration that consists of the same material composition for both anode and cathode is of great interest with advantages of better compatibility and low cost. [16] To avoid these issues, cathode without Nibased cermet electrode has been tried.…”

“…At present, the major symmetrical electrodes of S-SOEC are from SOFC, such as Sr 2 Fe 1.5 Mo 0.5 O 6-δ , [18,23] La x Sr 1-x Co y Fe 1-y O 3-δ , [21,24] and La x Sr 1-x Fe y Ni 1-y O 3-δ. [25,26] Spinel oxides with considerable conductivity, suitable structural stability and high reaction activity, have been widely investigated as electrodes for many energy storage devices.…”

“…It is found that some perovskites have been confirmed to be promising cathodes for SOEC. [17][18][19] Compared to the traditional SOEC, symmetrical cell configuration that consists of the same material composition for both anode and cathode is of great interest with advantages of better compatibility and low cost. Replacing Ni-YSZ cathode with the symmetrical ones also makes it possible to electrolyze cheap pure CO 2 and avoid carbon deposition and electrode delamination.…”