Supplementary Information. without safe gas

Transcription

1 Electronic Supplementary Material (ESI) for Journal of Materials Chemistry A. This journal is The Royal Society of Chemistry 2016 Supplementary Information Nanotructured ceramic fuel electrode for efficient CO 2 /H 2 O electrolysis without safe gas Yihang Li a, Pan Li b, Bobing Hu a, Changrong Xia* a a Key Laboratory of Materials for Energy Conversion, Chinese Academy of Sciences, Department of Materials Science and Engineering & Collaborative Innovation Center of Suzhou Nano Science and Technology, University of Science and Technology of China, No. 96 Jinzhai Road, Hefei, Anhui Province, , P. R. China. b Department of Chemistry, University of Science and Technology of China, No. 96 Jinzhai Road, Hefei, Anhui Province, , P. R. China. *Tel: ; Fax: ; xiacr@ustc.edu.cn

2 The fabrication of YSZ substrate The modified phase-inversion tape-casting method is described as follows. Polyethersulfone polymer (PESF, Veradel, Solvay Specialty Polymers, USA) and polyvinyl pyrrolidone (PVP, SINOPHARM Co., Ltd, China) were add into N-Methyl pyrrolidone (NMP, SINOPHARM Co., Ltd, China) in a weight ratio of NMP:PESF:PVP=20:4:1, followed by magnetic stirring for 12 h to obtain a light yellow colour, transparent solution. Then YSZ powder was mixed with polymer solution in a weight ratio of 4:6, ball-milling for 12 h to obtain a uniformly dispersed slurry. A graphite slurry containing 30wt.% graphite powders (Furunda Co., Ltd) was prepared by the same method. Table 1 shows the components of YSZ and graphite slurries. As shown in Fig. S1, the two slurries were co-tape cast on a carrier film with the blade height of 0.3 mm and 1 mm, and subsequently immersed into tap water bath for solidification via phase inversion process. Table S1 The components of YSZ and graphite slurries to fabricate YSZ substrate Components Weight ratio (%) Function YSZ 60 ingredient YSZ NMP 32 solvent slurry PESF 6.4 binder PVP 1.6 surfactant Graphite 30 ingredient Graphite NMP 56 solvent slurry PESF 11.2 binder PVP 2.8 surfactant

3 Fig.S1 Diagram for the modified phase-inversion tape-casting process for the preparation of YSZ substrate

4 Fig.S2 Schematic illustration of the apparatus for the testing of the single cells which are operated in both fuel cell and electrolysis modes

5 Fig.S3 The cross-sectional SEM image of a porous YSZ substrate

6 Fig.S4 EDX images of Zr, Y, Sr, Fe and Mo elements in a SFM-YSZ electrode.

7 Fig.S5 XRD pattern of the infiltrated SFM-YSZ electrode after heated at 850 o C for 5 hours.

8 Fig.S6 Electrochemical impedance spectra measured under open circuit conditions at o C

9 Fig.S7 Impedance spectra measured in air at 800 C for a symmetrical cell with LSM-YSZ as the electrodes and YSZ as the electrolyte. The electrolyte resistance has been subtracted from the impedance to clearly show the interfacial polarization resistance

10 Fig.S8 Raman spectra for the SFM-YSZ electrode (a) before and (b) after 25 h co-electrolysis testing Under high CO 2 and steam concentration conditions, the boudouard reaction (Eq. (1)) has an 2CO CO C 2 (1) unfavorable thermodynamics for carbon generation. However, CO can be further electrolyzed to produce element carbon under high potential, which could be deposited on the fuel electrode, resulting in degradation of the cell performance. 1 Fig.S8 shows the Raman spectra ( cm -1 ) of SFM-YSZ fuel electrode before and after 25 h co-electrolysis. In general, the peaks of amorphous carbon and carbon nanotube are located in the region of cm -1 and cm -1, respectively. 2 Nevertheless, both the peaks are not distinctly detected after CO 2 -H 2 O coelectrolysis testing in this study, indicating no carbon deposition occurred during the co-electrolysis process. Therefore, SFM-YSZ has a high selectivity for co-electrolysis of CO 2 -H 2 O to syngas.

11 References for supplementary information: 1 C. Gaudillere, L. Navarrete and J. M. Serra, Int J Hydrogen Energ, 2014, 39, X. X. Li, J. P. Lee, K. S. Blinn, D. C. Chen, S. Yoo, B. Kang, L. A. Bottomley, M. A. El-Sayed, S. Park and M. L. Liu, Energ Environ Sci, 2014, 7, 306.