Recently, an exciting research progress in designing advanced anode for methane reforming in solid oxide electrolysis cells (SOECs) by constructing stable metal-oxide interface via in situ exsolution was made by Prof. Xinhe Bao, Prof. Guoxiong Wang and their team. Various in situ physicochemical characterizations were applied to elucidate the mechanism of methane reforming at the SOEC anode.
SOEC stands out as one of the most commercially viable carbon-negative technologies due to its superior electrical efficiency, stability and modularity. Replacing sluggish oxygen evolution reaction with favorable CH4 reforming reaction (POM) at the anode of SOEC can greatly reduce the electrical demand for CO2 electroreduction at the cathode. However, the perovskite anode always displays limited activity and stability for CH4 reforming. Therefore, the development of POM anodes with high activity and stability is of great significance.
The team has made significant advances in high-temperature electrocatalysis based on SOECs in recent years. Previously, they developed a series of electrochemically active interfaces for high-temperature electrode reactions by in-situ exsolution and high-temperature self-dispersion strategies. In this work, they optimized the exsolution energy of B-site transition metal to promote the exsolution of Co and Fe in the La0.6Sr0.4Ti0.3Fe0.7-xCoxO3-δ, leading to in situ formation of CoFe alloy nanoparticles with an average size of 7nm and particle population of 1087 μm-2 on the surface of the La0.6Sr0.4Ti0.3Fe0.5Co0.2O3-δ (LSTFC2) perovskite, providing sufficient active center for anodic CH4 reforming reaction.
Moreover, in situ spectroscopy revealed that the electrochemical spillover oxygen could promote the adsorption and activation of CH4 and inhibit carbon deposition with improved stability of CH4 reforming. Finally, The La0.6Sr0.4Ti0.3Fe0.5Co0.2O3-δ anode shows superior anodic CH4 reforming performance with CH4 conversion of 86.9% and CO selectivity of 90.1% at 800 °C. Moreover, stable operation over 1250h with a CO selectivity above 95% is achieved. The electrical energy consumption for CO decreases from 3.46 kWh m-3 for conventional SOEC to 0.31 kWh m-3 for CH4-assisted SOEC. This work provides an efficient strategy to thermodynamically boost the cathodic CO2 electroreduction performance and simultaneously convert CH4 to syngas at the anode, paving a new path for efficient conversion of C1 molecules. This work was published as a research article in Joule. (Yige Guo and Yuefeng Song)
Link: https://doi.org/10.1016/j.joule.2024.04.009