Well-dispersed Pd 3Pt 1 alloy nanoparticles in large pore sized mesocellular carbon foam for improved methanol-tolerant oxygen reduction reaction

Abstract

Oxygen reduction reaction (ORR) catalysts, Pd 3Pt 1 nanoparticles with methanol tolerance, are supported on various carbon supports: mesocellular carbon foam (MSU-F-C), CMK-3, and Vulcan XC-72. The particle size of Pd 3Pt 1 (∼5 nm) is larger than the pore size of CMK-3 (∼3 nm), resulting in the agglomeration of Pd 3Pt 1 nanoparticles on the external surface of the CMK-3. The large surface area and large pore size of MSU-F-C allows a high degree of dispersion of Pd 3Pt 1 nanoparticles inside the pores. Due to its highly dispersed state, the Pd 3Pt 1/MSU-F-C shows higher ORR activity than Pd 3Pt 1/Vulcan XC-72 and Pd 3Pt 1/CMK-3. The charge transfer resistance ( R ct), as measured by electrochemical impedance spectroscopy, increases in the order of Pd 3Pt 1/CMK-3 > Pd 3Pt 1/Vulcan XC-72 > Pd 3Pt 1/MSU-F-C. Pd 3Pt 1/MSU-F-C is methanol tolerant at 400 rpm in the presence of 0.5 M CH 3OH, while methanol oxidation peaks are observed in the case of Pd 3Pt 1/Vulcan XC-72 and Pd 3Pt 1/CMK-3.