CO2 and H2O Electrolysis Using Solid Oxide Electrolyzer Cell (SOEC) with La and Cl- doped Strontium Titanate Cathode

• Published in: Catalysis letters Vol. 149; no. 7; pp. 1743 - 1752
• Main Authors: Dogu, Doruk, Gunduz, Seval, Meyer, Katja E., Deka, Dhruba J., Co, Anne C., Ozkan, Umit S.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.07.2019; Springer Nature B.V; Springer
• Subjects: Air pollution; Carbon dioxide; Catalysis; Cathodes; Chemistry; Chemistry and Materials Science; Coking; Earth surface; Electrical resistivity; Electrode materials; Electrolysis; Electrolytic cells; Emissions control; Fischer-Tropsch process; Fourier transforms; Greenhouse effect; Greenhouse gases; High temperature; Industrial Chemistry/Chemical Engineering; Nickel oxides; Organometallic Chemistry; Oxidation; Physical Chemistry; Raman spectroscopy; Spectrum analysis; Strontium titanates; Synthesis gas; Yttria-stabilized zirconia; Strontium titanate; Electrocatalysis; Perovskite; Electrolysis; Solid oxide electrolyzer cell (SOEC)
• ISSN: 1011-372X; 1572-879X
• DOI: 10.1007/s10562-019-02786-8

The average CO 2 concentration in atmosphere increased by 25 ppm in the last decade, and during the same period, the average global surface level temperature rose by 0.3 °C. CO 2 , one of the biggest contributors to climate change, is a greenhouse gas that traps the energy emitted by the earth’s surface, causing an increase in the temperature. Because of the greenhouse effect of CO 2 , a growing area of research is trying to find ways to minimize CO 2 emission and decrease the CO 2 concentration in the atmosphere. Besides reducing the CO 2 emission, it is also important to develop technologies to convert CO 2 into valuable products. One such product is syngas, a mixture of carbon monoxide and hydrogen that can be used as fuel, as well as for synthesis of hydrocarbons through Fischer–Tropsch synthesis. Intermediate and high temperature co-electrolysis of CO 2 and water using Solid Oxide Electrolyzer Cell (SOEC) is a promising method to produce syngas from CO 2 . This work focuses on the use of La 0.2 Sr 0.8 TiO 3±δ Cl σ as an SOEC cathode for CO 2 and H 2 O co-electrolysis, and its activity compared with conventional SOFC electrode material, Ni/NiO-YSZ. Electrocatalytically, it was found that Ni/NiO-YSZ outperforms La 0.2 Sr 0.8 TiO 3±δ Cl σ when only CO 2 is reduced, however, La 0.2 Sr 0.8 TiO 3±δ Cl σ shows higher activity for co-electrolysis of CO 2 and H 2 O. Post-reaction temperature-programmed oxidation testing performed on the co-electroylsis cells demonstrated less coking associated with La 0.2 Sr 0.8 TiO 3±δ Cl σ than Ni/NiO-YSZ, although both materials showed relatively lower levels of coking when H 2 O was not present. Interactions between the surfaces of these materials and CO 2 were characterized using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and Raman spectroscopy. These showed that CO 2 interacts more strongly with La 0.2 Sr 0.8 TiO 3±δ Cl σ than Ni/NiO-YSZ, forming carbonate species on the surface. The electrical conductivity of the materials was also compared, and while Ni/NiO-YSZ showed slightly higher values, the electrical conductivity of La 0.2 Sr 0.8 TiO 3±δ Cl σ increased more rapidly with temperature and was in the same order of magnitude as that of Ni/NiO-YSZ. Graphical abstract