Ultrafine jagged platinum nanowires enable high platinum mass activity for the oxygen reduction reaction

Improving the platinum (Pt) mass activity for the oxygen reduction reaction (ORR) should optimize both the specific activity and the electrochemical active surface area (ECSA). We show that solution-synthesized Pt/NiO core/shell nanowires can be readily converted into PtNi alloy nanowires through a post-synthesis thermal annealing process, and then transformed into jagged Pt nanowires via an electrochemical dealloying process. The jagged nanowires exhibit an ECSA of 118 square meters per gram Pt and a specific activity of 11.5 milliamperes per square centimeter for ORR (at 0.9 volt versus the reversible hydrogen electrode) for a mass activity of 13.6 ampere per milligram Pt, or nearly doubles previously reported best values. Reactive molecular dynamics simulations suggest that highly stressed, undercoordinated rhombohedral-rich surface configurations of the jagged nanowires enhanced ORR activity versus more relaxed surfaces. One Sentence Summary: We report the preparation of ultra-fine jagged Pt nanowires with highly stressed, under-coordinated rhombi-rich surface configurations that deliver a record high