Understanding the Effect of Temperature on the Sulfur Tolerance of a Ca Rich Ferrite SOFC Electrode
Bibliographic record
Abstract
Previously, we have shown that a symmetrical La 0.3 Ca 0.7 Fe 0.7 Cr 0.3 O 3-δ (LCFCr) SOFC full cell (LCFCr used at both electrodes) exhibits very good electrochemical performance in H 2 and CO at the fuel cell and also has good sulfur tolerance in wet H 2 with a low ppm H 2 S content at 800 o C [1]. In fact, a somewhat enhanced performance of the LCFCr anode towards the hydrogen oxidation reaction was observed under these conditions [1]. However, the effect of temperature, which is known to have a significant impact on the sulfur tolerance of conventional Ni-based anodes [2-6], has not yet been studied. Therefore, in this work, both a symmetrical full cell and a three electrode half cell configuration, using LCFCr for all of the electrodes, were constructed and tested to better understand the sulfur tolerance of this Ca rich ferrite based perovskite in humidified H 2 at temperatures ranging from 600-800 o C. Our preliminary potentiostatic data have shown that, in both the full and half-cell mode in low ppm H 2 S, the LCFCr electrode exhibits an enhancement in the hydrogen oxidation reaction (HOR) kinetics at 750-800 o C, while between 600 and 700 o C, the LCFCr electrode shows some form of deactivation. For instance, in the three electrode half-cell study at a constant anodic overpotential of 100 mV, the current density of the LCFCr electrode increased by 7-10% with the addition of 9 ppm H 2 S to 50% humidified H 2 in the higher temperature range, while at 600 o C and 650 o C, the current density decreased by 2% and 15%, respectively. This deactivation was found to be fully reversible when H 2 S was removed from the gas stream, however, indicating that there was no permanent damage to either the electrodes, the interfaces, or the current collectors. Similarly, open circuit impedance data for the symmetrical full cell study showed that the polarization resistance (Rp) decreased from 1.0 to 0.95 Ωcm 2 with the addition of 9 ppm H 2 S to 30% humidified H 2 at 800 o C, while at 650 o C, Rp increased from 15.3 to 17.6 Ωcm 2 . To better understand these results, we are employing various surface characterization techniques, such as X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES), to better understand the interaction between H 2 S and LCFCr, as well as the type of S species formed, over the full temperature range in low ppm H 2 S. References [1] P. K. Addo, B. Molero-Sánchez, A. Buyukaksoy, S. Paulson and V. Birss, ECS Trans., 66 (2) , 219 (2015). [2] L. Debeeleeck et al, Phys.Chem.Chem.Phys., 16 , 9383(2014). [3] J.-H. Wang, M. Liu, Electrochem. Commun., 9 , 2212 (2007). [4] D.G. Ivey et al, J. Power Sources, 195 , 6301 (2010). [5] C. Bartholomew, Appl. Catal. A: Gen., 212 , 17 (2001).
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".