PtNi alloy nanoparticles prepared by nanocapsule method for ORR catalysts in alkaline media

Nanocapsule methods could effectively provide metal and alloy nanoparticles with well-controlled particle size and size distribution by reducing metal complexes in reverse-micelles. Specifically, PtCo alloy nanoparticles deposited on carbon prepared by nanocapsule method exhibited high oxygen reduction reaction (ORR) activity in alkaline solution. A series of PtNi alloy nanoparticles deposited on acetylene black carbon support were synthesized via original nanocapsule method so that the alloy compositions, particles sizes and their distribution were well-controlled. PtNi/C exhibited high ORR activity with volcano-type dependence on the composition, where the optimum content of Ni was ca. 50 atom%. The enhancement of the catalytic activity in alkaline solution revealed a very narrow range of Ni content, similar to that of PtCo/C. Since the nanocapsule method is applicable to many other binary and even ternary alloy nanoparticles, more active alloy or non-precious metal catalysts may be found in the future.