Proton exchange membrane fuel cells powered with both CO and H 2

Significance We report a class of IrRu-N-C catalysts, with Ir and Ru single atoms uniformly populated in nitrogen–carbon composites. The catalyst not only represents an example of high-efficiency single-atom catalysis toward H 2 electrooxidation, but also exhibits excellent CO electrooxidation reaction (COOR) behavior. The traditionally invincible CO electrooxidation process occurs easily on this catalyst, with COOR initiates at nearly 0 mV versus reversible hydrogen electrode at ambient temperature. This endows the catalyst with superb CO antipoisoning property in proton exchange membrane fuel cell at ultralow noble metal loading. Combining theoretical calculation and physical probing techniques, we find that the approximated Ir and Ru single atomic sites act in synergy to confer the catalysts with this excellent CO conversion behavior.