Mesostructured Pt-Based Bimetallic Nanospheres as Ultrastable Self-Supported Oxygen Reduction Electrocatalysts

Abstract

Enhancing the activity and stability of cathode catalysts in proton exchange membrane fuel cells (PEMFCs) is of great importance for their widespread commercialization. While nanostructured Pt-based nanoparticles supported on carbon have been the most active cathode catalysts, their long-term durability and their implementation n single cells represent challenges. In this work, we report the self-supported, mesostructured Pt-based bimetallic (Meso-PtM; M=Ni, Fe, Co, Cu) nanospheres containing intermetallic phase, which can combine the beneficial effects from transition metal (M), intermetallic phase, interconnected framework, and porous structure. All Meso-PtM nanospheres showed enhanced ORR activity, compared to Pt black and Pt/C catalysts. Particularly, Meso-PtNi with intermetallic phase exhibited ultrahigh stability, showing enhanced ORR activity even after 50,000 potential cycling, whereas Pt/C underwent a dramatic degradation. Importantly, the superior performance of Meso-PtNi with intermetallic phase was also demonstrated in a PEMFC single cell. The initial mass activity of Meso-PtNi far exceeded that of Pt/C and the US DOE target value, and represents one of the best activities among Pt nanocatalyst-based PEMFCs.