Synthesis of olive-shaped mesoporous platinum nanoparticles (MPNs) with a hard-templating method using mesoporous silica (SBA-15).

Well-ordered mesoporous Pt nanoparticles (MPNs) with uniform olive shapes are synthesized by using two-dimensional (2D) hexagonal mesoporous silica (SBA-15) as a hard template. The average particle sizes are controllable in the range of 150 to 230 nm by changing the reduction time. Low-angle XRD profiles for the obtained MPNs show three distinct peaks assignable to the (10), (11), and (20) planes of a highly ordered 2D hexagonal symmetry. From high-magnification SEM images, periodically arranged Pt nanowires are observed clearly, which are a negative replica of the 2D hexagonally ordered mesoporous silica (SBA-15). Furthermore, the single crystallinity of the Pt fcc structure coherently extends over the whole particles. As a result of such unique character as well as high surface area, the obtained MPNs show distinctly enhanced electrocatalytic properties for methanol oxidation reaction compared to other Pt samples, such as Pt black.