Supplementary Information

Nanotructured ceramic fuel electrode for efficient CO2/H2O 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,

230026, P. R. China.

b Department of Chemistry, University of Science and Technology of China, No.

96 Jinzhai Road, Hefei, Anhui Province, 230026, P. R. China.

*Tel: +86-551-63607475; Fax: +86-551-63601696; E-mail: xiacr@ustc.edu.cn

Electronic Supplementary Material (ESI) for Journal of Materials Chemistry A.This journal is © The Royal Society of Chemistry 2016

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

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

substrate

Fig.S2 Schematic illustration of the apparatus for the testing of the single cells which are operated

in both fuel cell and electrolysis modes

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

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

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

Fig.S6 Electrochemical impedance spectra measured under open circuit conditions at 700-800 oC

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

Fig.S8 Raman spectra for the SFM-YSZ electrode (a) before and (b) after 25 h co-electrolysis

testing

Under high CO2 and steam concentration conditions, the boudouard reaction (Eq. (1)) has an

(1)22CO CO C

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 (100-2000 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 1350-1400 cm-1 and 1550-1600

cm-1, respectively.2 Nevertheless, both the peaks are not distinctly detected after CO2-H2O co-

electrolysis 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 CO2-H2O to syngas.

References for supplementary information:1 C. Gaudillere, L. Navarrete and J. M. Serra, Int J Hydrogen Energ, 2014, 39, 3047.2 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.