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 solution-synthesized Pt/NiO core/shell nanowires can be converted into PtNi alloy nanowires through a thermal annealing process, and then transformed into jagged Pt nanowires via an electrochemical dealloying. The jagged nanowires exhibit an ECSA of 118 m2 per gram Pt and a specific activity of 11.5 mA per square centimeter for ORR (at 0.9 V versus reversible hydrogen electrode) for a mass activity of 13.6 ampere per milligram Pt, nearly doubling previously reported best values. Reactive molecular dynamics simulations suggest that highly stressed, under-coordinated rhombohedral-rich surface configurations of the jagged nanowires enhanced ORR activity versus more relaxed surfaces.

Science 17 Nov 2016:
DOI: 10.1126/science.aaf9050

http://science.sciencemag.org/content/early/2016/11/16/science.aaf9050