Z. Liu, H. Yang, M. Resch, C. David, C. Hahn
Dioxide materials,
United States
Keywords: carbon dioxide conversion, impurity effects, electrolyzer
Summary:
There is considerable interest in using waste CO 2 as a feedstock for e-fuels. Generally, one uses an electrolyzer to convert CO 2 into C1 or C2 intermediates. These intermediates are then converted to e- fuels. To date, literature reports have been concentrated on converting pure CO 2 into e-fuels. However, most industrial sources of waste CO 2 contain impurities, and the effects of those impurities have not been extensively explored. Here, we explore the effect of a common impurity, H 2 S, on the performance of a CO 2 electrolyzer. We found that H 2 S did not behave as expected. Normally, when one feeds an impurity into the cathode of an electrochemical device, the cathode is poisoned. Here, we found the opposite: the cathode was unaffected, but the anode was poisoned. We also observed slow sulfur-stimulated silver electromigration from the cathode to the anode. To our knowledge, this is the first time that an impurity in the feed has been shown to increase the rate of metal migration through an electrochemical device. Other unexpected findings included a degradation rate largely independent of the H 2 S concentration over the range of 3 ppm to 25 ppm, and the rate strongly depended on the electrolyzer current.