Catalytic activity and stability of Pt/TiO2, Pt/TiN, and Pt/TiC catalysts for oxygen reduction reaction in PEM fuel cells
Proton exchange membrane fuel cells (PEMFCs) are electrochemical energy devices which have become a major source of clean energy for automotive applications. Despite significant recent advances, the instability of carbon supported Pt nanoparticle cathode catalyst due to carbon support corrosion and weak metal-support interaction is still a critical problem. In order to address this issue, TiO2, TiN, and TiC supported Pt nanoparticles catalysts were synthesized using a simple polyol process. The oxygen reduction reaction (ORR) activity and durability of the synthesized catalysts have been investigated in acidic media of PEMFCs using rotating disk electrode (RDE) technique and compared with the commercial carbon supported Pt catalyst. The average Pt nanoparticles sizes are 1.95, 2.30, and 2.63 nm for the Pt/TiO2, Pt/TiN, and Pt/TiC catalysts, respectively. Among these three synthesized catalysts, the Pt/TiC catalyst has the highest stability and best catalytic performance with higher ORR current, electrochemical surface area (ECSA) and mass specific activity. The ORR performance of the synthesized Pt/TiC catalyst is found to be promising with higher area specific activity (Is) of 252 µA cm-2Pt and slightly lower mass specific activity (Im) of 0.16 A mg-1Pt than that of the Pt/C with Is of 235.5 µA cm-2Pt and Im of 0.17 A mg-1Pt. Additionally, the Pt/TiC shows the outstanding stability with no reduction in ORR performance and 10.1% increase in ECSA after accelerated stress test (AST).