Electrochemical reduction of Carbon Dioxide on Ceria Based Cathode for Solid Oxide Electrolyser

Neetu Kumari, M. Ali Haider and S. Basu^*

Department of Chemical Engineering, Indian Institute of Technology Delhi, New Delhi 110016

*corresponding author and presenter Tel 91 11 26591035 Fax 91 11 26581120

E-mail: sbasu@iitd.ac.in

Generation of electrochemical fuels like hydrogen by water splitting ^[1] and carbon monoxide ^[2-3] or hydrocarbons^[4] by electrochemical reduction of carbon dioxide (CO₂) in solid oxide electrolysis cell (SOEC) has been tried by many investigators. Apart from generating fuels, electrochemical reduction of CO₂ is an attracting approach to clean our environment or reduced the global warming effect. In this study, ceria based materials have been tested for electrochemical reduction of CO₂ by fabricating a solid oxide electrolysis cell (SOEC). The configuration of SOEC used is: cathode 20 % gadolinium doped ceria (GDC), electrolyte 8% yatria stabilized strontium (YSZ) and anode lanthanum strontium manganite (LSM). The electrochemical performance of the cell is measured by impedance spectroscopy and current-voltage measurements. To design the catalyst for electrochemical reduction of CO₂ we have also performed Density Functional Theory (DFT) calculation. First, we have studied the adsorption and activation of CO₂ on stoichiometric (CeO₂) as well as reduced (CeO_2-x) ceria surface and second, we have dissociated it through a sequence elementary reaction steps to study the reaction mechanism and rate determining step of the reaction. All the calculations have been performed in Material Studio (version-7.0) using DMol3 module. The configuration of adsorbed CO₂ on stoichiometric surface as well as on reduced surface is carried out. The reduced form of surface is more effective for CO₂ adsorption and activation, as it is giving higher adsorption energy (in –ve) and bent structure of adsorbed CO₂. Energy required to create one O-vacancy is shown in figure 3b, these results are comparable with the earlier work by Z. Cheng et al. ^[5] This entire study will help us to understand the functioning of ceria material for CO₂ reduction process.

References

[1]   A. Brisse, J. Schefold, M. Zahid, Int. J. Hydrogen energy, 2008, 33, 5375–5382.

[2]   R.D. Green, C.-C. Liu, S.B. Adler, Solid State Ionics. 2008, 179, 647–660.

[3]   C-Y. Cheng, G. H. Kelsall, L. Kleiminger, J. Appl. Electrochem, 2013, 43,1131–1144

[4]   W. Li, H. Wang, Y. Shi, N. Cai, Int. J. Hydrogen energy, 2013, 38, 11104–11109.