Tailoring of Pt Island RuO₂/C Catalysts by Galvanic Replacement to Achieve Superior Hydrogen Oxidation Reaction and CO Poisoning Resistance

For the commercialization of fuel cells, it is necessary to use pure hydrogen. This is because carbon monoxide (CO) present in hydrogen generated by the reformation of hydrocarbon-based fuels directly affects the fuel cell performance when Pt is used. To improve CO oxidation reactions on the Pt surface, various methods have been reported such as tuning the electronic structure of Pt to weaken the Pt-CO bond (electronic effect) and increasing the amount of the supplied oxygen species (bifunctional effect). Herein, we synthesized a Pt island RuO2/C (PiR/C) catalyst, in which Pt nanoparticles were placed like islands on RuO2 using the galvanic replacement method. PiR/C showed excellent hydrogen oxidation reaction activity despite its low Pt content. The analysis of the electronic structure of Pt confirmed that PiR/C prevents CO poisoning. Additionally, electrochemical analyses including CO stripping and CO bulk oxidation were performed. By these analyses, it is confirmed that CO was first removed at the high CO coverage on the PiR/C surface by the Eley-Rideal mechanism and further CO oxidation reactions were promoted by the Langmuir-Hinshelwood mechanism. Finally, superior CO management under the actual operating conditions of PiR/C was verified by single-cell analysis.