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Microstructure and Electrochemical Properties of La0.8Sr0.2Ga0.8Mg0.

Traditional Ni/YSZ anode SOFCs were modified by Sn, Cu and Ag by an infiltration method to obtain Sn-Ni, Cu-Ni and Ag-Ni alloy anode catalysts on the anode. The obtained maximum power density of Ni/YSZ, Sn-doped Ni/YSZ, Cu-doped Ni/YSZ, and Ag-Ni/YSZ cells fuelled by simulated biogas (14 mL min −1 CH 4 , 7mL min −1 CO 2 and 7mL min −1 N 2 ) at 750°C were 0.101, 0.272, 0.085 and 0.102 W cm −2 respectively. Stability tests of SOFCs in biogas revealed that the stability of Sn-Ni/YSZ and Ag-Ni/YSZ cells in operation was greatly improved compared to the undoped Ni/YSZ cell. Both Sn-Ni/YSZ and Ag-Ni/YSZ cells stably operated for 48 h, but Ni/YSZ cell ceased operation after 19 h due to carbon deposition. The addition of small amount of Cu did not enhance the anti-coking ability. Other than with the severe carbon deposition on the Ni/YSZ anode surface, no observable fibrous carbon could be identified on the Sn-Ni/YSZ and Ag-Ni/YSZ anode surfaces.

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Link to publication on Research at Birmingham portal General rights Unless a licence is specified above, all rights (including copyright and moral rights) in this document are retained by the authors and/or the copyright holders. The express permission of the copyright holder must be obtained for any use of this material other than for purposes permitted by law. • Users may freely distribute the URL that is used to identify this publication. • Users may download and/or print one copy of the publication from the University of Birmingham research portal for the purpose of private study or non-commercial research. • User may use extracts from the document in line with the concept of 'fair dealing' under the Copyright, Designs and Patents Act 1988 (?) • Users may not further distribute the material nor use it for the purposes of commercial gain. Where a licence is displayed above, please note the terms and conditions of the licence govern your use of this document. When citing, please reference the published version. Take down policy While the University of Birmingham exercises care and attention in making items available there are rare occasions when an item has been uploaded in error or has been deemed to be commercially or otherwise sensitive.

This work is aimed at evaluating the influence of carbon deposition on the power density drop of in-house fabricated Ni/YSZ and Ni/ScSZ solid oxide fuel cells (SOFCs) operating in dry internal reforming of simulated biogas (CH 4 / CO 2 = 2). An immediate drop of open-circuit voltage (OCV) and maximum power densities is observed when the fuel changes from hydrogen to biogas, 86.5% and 33.3% for the Ni/YSZ and Ni/ScSZ cells, respectively with mass transfer polarisation dominates Ni/YSZ polarisation. Carbon deposition is investigated as the cause of the reduction in performance by quantification of deposited carbon by temperature programmed oxidation (TPO) and catalytic activity test. Results from TPO analysis show unexpectedly higher amount of carbon on the Ni/ScSZ cells (2.35 × 10 −3 mgC/mg cat) as compared to Ni/YSZ (5.68 × 10 −4 mgC/mg cat) despite higher performance of the former. Catalytic activity tests reveal a low carbon oxidation rate compared to an initially higher methane decomposition reaction, leading to carbon deposition in both cells, in which the methane decomposition reaction of Ni/ScSZ is higher. Different effects are observed on the pellets, where the carbon deposited on Ni/YSZ deactivates the reforming reaction sites as quick as 20 minutes into the operation, whereas carbon deposited on the Ni/ScSZ pellet did not show the same blocking effect on the catalyst due to the different carbon morphology formed. A graphitic whisker-like rod structure is observed on Ni/ScSZ while amorphous non-crystalline carbon covers the Ni/YSZ pellets with 3 hours exposure to high methane content dry biogas (CH 4 /CO 2 = 2). The difference of carbon structure affects the amount of carbon quantified in the TPO analysis where most of the amorphous carbon oxidises while some of the graphitic carbon deposits remain.

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