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

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