(544he) High Temperature Co-Electrolysis of CO2 and H2o on La0.9-XSrxNiyCozFe1-y-ZO3-? Type Cathode Catalysts

Due to the detrimental effect of CO₂ as a greenhouse gas, its capture and storage have become an active area of research. Instead of storing in wells, if the captured CO₂ is converted into value added products, a closed carbon cycle can be achieved [1]. In this study, a high temperature (800°C) solid oxide electrolysis cell (SOEC) is employed to co-electrolyze H₂O and CO₂ into synthesis gas, which can be turned into valuable chemicals by Fischer-Tropsch synthesis.

The SOEC used for this purpose consists of an yttria-stabilized zirconia (YSZ) solid oxide oxygen ion conductive electrolyte, sandwiched between two electrode layers. The anode consists of a commercially available mixture of lanthanum strontium manganite (La_0.8Sr_0.2MnO₃) and YSZ, whereas the cathode consists of an inhouse developed perovskite oxide. H₂O and CO₂ get electrolyzed at the cathode to produce H₂ and CO along with O^2- ions; these oxide ions then travel through the YSZ electrolyte to the anode where they combine to form molecular oxygen.

In this study, La_0.7Sr_0.2FeO₃ type perovskite materials were synthesized via EDTA-citric acid complexation method [2] and doped at the B-site with Ni and Co and then tested as cathode catalysts. The synthesized materials were characterized using XRD, XANES, LRS, XPS, DRIFTS and four probe DC van der Paw techniques to investigate their morphology, bulk and surface structure and electrical conductivity. The electrocatalytic activity tests performed at 800 °C showed that the synthesized perovskites are highly active in co-electrolysis of CO₂ and H₂O showing a Faradaic efficiency as high as 100% and the produced syngas composition can be altered by changing the B-site doping ratios.

[1] Van Nhu Nguyen, Ludger Blum, Syngas and Synfuels from H₂O and CO₂: Current Status, Chemie Ingenieur Technik (2015), 87(4), 354-375.

[2] N.A. Abdullah, S. Hasan, N. Osman, Role of CA-EDTA on the Synthesizing Process of Cerate-Zirconate Ceramics Electrolyte, Journal of Chemistry, 2013 (2013), 1-7.