Thanks to the substantial efforts devoted by scientists like Radoslav Adzic in the past few decades, significant progress has been made in improving the activity and durability of platinum toward the oxygen reduction reaction (ORR), making it now practical catalysts for proton exchange membrane fuel cells (PEMFCs) in automotive fuel cells and many other applications.¹ Several pathways have been developed to improve the inherent ORR performance of Pt and its utilization, which guides and is guided by the fundamental understandings of the ORR catalysis gained by combined experimental and computational efforts. The most popular strategy is to alloy Pt with a wide range of transition metals (denoted as M) including but not limited to Cr, Ni, Y, Pd, and Au.^2-6 The strain and/or ligand effects induced by M improve the ORR kinetics via optimizing the Pt-O binding energy and surface coordinate configuration. In particular, a new electrocatalyst that uses a single layer of platinum on the core of M initiated by Adzic’s group not only greatly enhances the Pt utilization, but provides a well-defined nanoscale system for fundamental studies.⁵ The second method involves supporting Pt nanoclusters on various metal oxides such as NbO_x,⁷ and the strong metal and support interactions are believed to account for the improved durability and/or activity towards the ORR. The third pathway is to directly decorate the Pt surface with metal oxides that stabilize the favorable Pt₃M(111) surface morphology via stabilization of shaped Pt nanoclusters enriched with low-coordinate Pt sites and subsurface M against acidic dissolution.^8,9 In this talk, recent achievements in the three pathways and the associated fundamental understandings will be presented.

Acknowledgement:

The authors deeply appreciate financial assistance from the U.S. Department of Energy, EERE (DE-EE-0000459). Use of the National Synchrotron Light Source (beamline X3B), Brookhaven National Laboratory (BNL), was supported by the U.S. Department of Energy, Office of Basic Energy Sciences. This publication was made possible by the Center for Synchrotron Biosciences grant, P30-EB-009998, from the National Institute of Biomedical Imaging and Bioengineering (NBIB). Support from beamline personnel Dr. Erik Farquhar and Mark Chance (X3B) are gratefully acknowledged. MRCAT operations are supported by the Department of Energy and the MRCAT member institutions. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.

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