Mesoporous microcapsules with noble metal or noble metal oxide shells and their application in electrocatalysis

Abstract

A versatile peripheral-pore-nanocasting method is employed to fabricate a series of novel microcapsules with mesoporous shell of noble metal or noble metal oxides, including Pt, PdO, RuO2 and IrO2. The shell thickness of these hollow microcapsules can be adjusted by controlling the depth of 3-amino-propyltriethoxysilane (APS) modification. By pre-filling the guest species or their precursors into the 3-D pores of HMS (hexagonal mesoporous molecular sieves) spheres, an interesting material with a “sphere in shell” structure could be fabricated via the same method. Both the mesoporous platinum hollow microcapsules and carbon spheres encapsulated in platinum microcapsules have shown high mass-normalized activities as a catalyst in the oxidation of methanol, a fundemantal reaction in direct methanol fuel cells (DMFC).