New Synthesis of MCM-48 Nanospheres and Facile Replication to Mesoporous Platinum Nanospheres as Highly Active Electrocatalysts for the Oxygen Reduction Reaction

Self-supported mesoporous Pt nanospheres are prepared by the templated method for the electrocatalytic oxygen reduction reaction (ORR). Single-crystal-like MCM-48 nanospheres, synthesized via a new and simple route in a dilute and alkaline solution of benzylcetyldimethylammonium chloride, are applied as the hard template. A facile process of molten salt impregnation followed by hydrogen reduction is developed to replicate both the mesostructure and morphology of the hard template and to form mesoporous Pt nanospheres. The high-surface-area mesoporous Pt nanospheres are thermally stable in air up to 300 °C without showing significant metal sintering. Electrocatalytic studies reveal that mesoporous Pt nanospheres have a large fraction of {110} facets and exhibit high activity for the ORR. The excellent electrocatalytic performance may be mainly attributed to the facet-dependent ORR activities as well as the presence of 3D interconnected mesopores to facilitate mass transport.