Nanoscale Structure Design for High-Performance Pt-Based ORR Catalysts.

Proton-exchange-membrane fuel cells (PEMFCs) are of considerable interest for direct chemical-to-electrical energy conversion and may represent an ultimate solution for mobile power supply. However, PEMFCs today are primarily limited by the sluggish kinetics of the cathodic oxygen reduction reaction (ORR), which requires a significant amount of Pt-based catalyst with a substantial contribution to the overall cost. Hence, promoting the activity and stability of the needed catalyst and minimizing the amount of Pt loaded are central to reducing the cost of PEMFCs for commercial deployment. Considerable efforts have been devoted to improving the catalytic performance of Pt-based ORR catalysts, including the development of various Pt nanostructures with tunable sizes and chemical compositions, controlled shapes with selectively displayed crystallographic surfaces, tailored surface strains, surface doping, geometry engineering, and interface engineering. Herein, a brief introduction of some fundamentals of fuel cells and ORR catalysts with performance metrics is provided, followed by a detailed description of a series of strategies for pushing the limit of high-performance Pt-based catalysts. A brief perspective and new insights on the remaining challenges and future directions of Pt-based ORR catalysts for fuel cells are also presented.