Hierachically structured mesoporous carbons as fuel cell electrode materials

Abstract

With a hollow core mesoporous shell geometry, porous carbon can be structured to tune surface area for reaction, nanopore diameter and length for transport, and protection of metal nanoparticles. Studies are reported for methanol oxidation and oxygen reduction using Pt and PtRu nanoparticles supported in a carbon structure composed of hollow core coated with a mesoporous shell (HCMS). The structural parameters can be tuned to study the combined effects of surface area, mesopore size, macropore size, and hierarchy of porosity. The distribution of Pt and PtRu nanoparticles in a mesoporous carbon can vary by tuning synthetic parameters and compared for activity and utilization. For methanol oxidation, the particles dispersed into a thicker shell are more stable and give better performance over time, as shown in voltage cycling and extended methanol oxidation. Preliminary results on oxygen reduction reaction show that the HCMS structure can offer superior mass transport and a high diffusion limiting current, in addition to durability over cycles of accelerated degradation tests.