Dependence of Syngas Composition on Microstructure of La0.8Sr0.2Cr0.5Mn0.5O3–δ Based Cathode for CO2 and H2O Co-Electrolysis

Thursday, 27 July 2017
Grand Ballroom East (The Diplomat Beach Resort)
M. Maide, K. Lillmaa, G. Nurk, and E. Lust (Institute of Chemistry, University of Tartu)
Ceramic materials with perovskite structure have attracted attention as possible redox stable, sulfur- and carbon tolerant cathode materials for solid oxide electrolysis cells 1,2. For example, composite cathode based on La0.8Sr0.2Cr0.5Mn0.5O3-δ (LSCM) are used for high temperature electrolysis of steam and co-electrolysis of steam and carbon dioxide 3,4. However, the limitation of electrochemical performance of electrolysis cell due to insufficient electrocatalytic activity can be a serious challenge 5.

In this study, catalytically active nickel and copper nanoparticles were grown on the surface of A-site deficient LSCM via redox exsolution. Influence of water-gas shift reaction activity conditions of electrolysis and nanocatalyst properties on the outlet gas composition were evaluated.

Electrolysis cells were prepared by sandwiching dense Zr0.89Sc0.10Ce0.01O2-δ (ScCeSZ) electrolyte layer between porous ScCeSZ layers and followed by wet impregnating of electrocatalytically active electrodes into the porous matrix. Impregnated salt mixture is decomposed at 400 °C, calcined and then sintered at 1400°C for 5 h. The thicknesses of the dense electrolyte and the porous scaffold were approximately 100 μm and 40 μm, respectively. Scanning electron microscopy, X-ray diffraction, FIB-TOF-SIMS and ICP-MS methods were used to characterize materials. Electrochemical characterization and analysis of outlet gas composition using gas chromatography was carried out at temperature range from 650 to 850 °C in various H2O, CO2, Hand Ar inlet concentrations.

As expected, the activity of composite cathode was greatly enhanced by the exsolved nickel and copper nanoparticles. For gas compositions the influence of water-gas shift (WGS) for nickel was greater than for copper.

Thus, it has been demonstrated that both nickel and copper nanoparticles can enhance the electrolytic activity of the cathode for steam electrolysis and co-electrolysis of steam and carbon dioxide. Influence of water-gas shift reaction at co-electrolysis conditions and properties of nanocatalysts on the outlet gas composition were evaluated.


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