Pt-Based Mesostructured Nanospheres Containing an Intermetallic Phase as Ultrastable Self-Supported Catalysts for Oxygen Electroreduction

Abstract

Developing highly active and stable cathode catalysts is of pivotal importance for proton exchange membrane fuel cells (PEMFCs). While Pt-based, carbon-supported nanocatalysts showed excellent oxygen reduction reaction (ORR) activities in rotating disk electrode (RDE) measurements, highly active catalysts have been reported sporadically in single-cell configuration, which has more practical relevance. In addition, considering the practical applicability of new ORR catalysts, the development of highly durable ORR catalysts capable of mitigating the dissolution of Pt and/or the corrosion of the carbon support is of critical importance. In this presentation, we report self-supported mesostructured Pt-based bimetallic (Meso-PtM; M = Ni, Fe, Co, Cu) nanospheres containing an intermetallic phase, which can combine the beneficial effects of transition metals, an intermetallic phase, a 3D interconnected framework, and a mesoporous structure. Meso-PtM nanospheres showed enhanced ORR activity, compared to Pt black and Pt/C catalysts. Notably, Meso-PtNi containing an intermetallic phase exhibited ultrahigh stability, showing enhanced ORR activity even after 50,000 potential cycles, whereas Pt black and Pt/C underwent dramatic degradation. Importantly, Meso-PtNi with an intermetallic phase also demonstrated superior activity and durability when used in a PEMFC single-cell, with record-high initial mass and specific activities.