| [Electrochemistry] Exsolution of Transition Metal Nanoparticles for Solid Oxide Co-Electrolysis of CO2-H2O Exsolution of Transition Metal Nanoparticles for Solid Oxide Co-Electrolysis of CO2-H2O Vasileios Kyriakou1; Dragos Neagu2; Michail Tsampas3; 1DUTCH INSTITUTE FOR FUNDAMENTAL ENERGY RESEARCH (DIFFER), Eindhoven, Netherlands; 2NEWCASTLE UNIVERSITY, Newcastle, United Kingdom; 3DIFFER, Eindhoven, Netherlands; PAPER: 112/Physical/Regular (Oral) SCHEDULED: 16:45/Thu. 24 Oct. 2019/Aphrodite B (100/Gr. F) ABSTRACT: The production of synthetic fuels from renewable energy could be a more efficient solution for a sustainable future without the need of huge investments for modifications in the existing infrastructure [1,2]. The raw material of synthetic fuels via the Fischer-Tropsch process is syngas (H<sup>2+</sup>CO) and is primarily generated by fossil fuels. The co-electrolysis of carbon dioxide and steam in a solid oxide electrolysis cells (SOECs) is an emerging route to produce syngas and thus store renewable electricity in the form of chemical bonds [2]. The commonly employed materials for fuel electrodes (cathode) in the process are Ni based cermets that exhibit high ionic-electronic conductivity and electrocatalytic activity. Nevertheless, Ni-YSZ electrodes suffer from coarsening under redox conditions and coking under carbon rich environments [3]. To circumvent coarsening, a reducing agent, such as hydrogen or carbon monoxide, is always co-fed with CO<sub>2</sub>-H<sub>2</sub>O in order to keep Ni in a reducing state [2]. Perovskite oxide ceramics (ABO3) are the most promising alternative fuel electrodes. Perovskites exhibit mixed ionic-electronic conductivity as single phases and can accommodate several kinds of defects under redox conditions, allowing them to adapt to various external conditions and therefore maintain stability and functionality under redox environments [4]. Lanthanum titanates constitute an intriguing class of perovskites, exhibiting chemical, dimensional, thermal and mechanical stability. By controlling deficiency of the A-site, transition metal nanoparticles may be exsolved to the surface from the perovskite oxide backbone under reducing environments. The grown particles are uniformly dispersed as well as anchored to the perovskite scaffold, thus rendering them more catalytically active and chemically stable compared to the oxide supported counterparts prepared by infiltration [5-7]. Along these lines, here we report on the electrochemical performance of (LaCa)(MTi)O<sub>3</sub> (M=transition metal) as fuel electrodes for high temperature CO<sub>2</sub>-H<sub>2</sub>O co-electrolysis. The cells are characterized and tested at 800-850°C under several feed mixtures (CO<sub>2</sub>/H<sub>2</sub>O, H<sub>2</sub>O/H<sub>2</sub>, CO<sub>2</sub>/ H<sub>2</sub>O/H<sub>2</sub>, CH<sub>4</sub>/H<sub>2</sub>O-CO<sub>2</sub>) and applied voltages. References: [1] J.A.Ritter, A.D, Ebner, Separation Science and Technology 2007, 42, 1123-1193. [2] S. D. Ebbesen, R. Knibbe, M. Mogensen, Journal of Electrochemical Society 2012, 159, F482-F489. P. Hjalmarsson, [3] S. D. Ebbesen, C. Graves, A. Hauch, S. H. Jensen, M. Mogensen, Journal of the Electrochemical Society 2010, 157, B1419-B1429. [4] Y. Zheng, J. Wang, B. Yu, W. Zhang, J. Chen, J. Qiao, J. Zhang, Chem. Soc. Rev. 46 (2017) 1427-1463. [5] D. Neagu, G. Tsekouras, D.N, Miller, H,Menard, J.T.S. Irvine, Nature Chemistry 2013, 11, 916-923. [6] J-H. Myung, D. Neagu, D.N, Miller, J.T.S. Irvine, Nature 2016, 537 (7621), 528-531. [7] L. Ye, M. Zhang, P. Huang, G. Guo, M. Hong, C. Li, J.T.S. Irvine, K. Xie, Nature Communications 2017, 8, 14785, doi: 10.1038/ncomms14785. |
