Vapor infiltration of a reducing agent for facile synthesis of mesoporous Pt and Pt-based alloys and its application for the preparation of mesoporous Pt microrods in anodic porous membranes

Highly ordered mesoporous Pt and Pt-based alloy (Pt-Ru and Pt-Ni) microparticles were deposited from lyotropic liquid crystal (LLC) films containing corresponding metal species via vapor infiltration of a reducing agent of dimethylaminoborane (DMAB). The LLC films with 2D hexagonal symmetry were prepared on flat substrates from diluted surfactant solutions including water, nonionic surfactant, ethanol, and metal species by drop-coating. Low-angle XRD measurements and TEM observations proved that the deposited Pt and Pt-based alloy microparticles have 2D hexagonally ordered mesoporous structures. Moreover, EDS mapping of mesoporous Pt-Ru microparticles indicated that the constituent metals are well-distributed within the mesopore walls. Moreover, we effectively utilized the method to fabricate mesoporous Pt microrods with 100 nm in diameter by using a porous anodic alumina membrane (PAAM) as a hard template. The Pt microrods possess a highly porous nanostructure. Our method utilizing vapor infiltration of a reducing agent, unlike conventional electrochemical and chemical deposition methods, allows the facile preparation of mesoporous metal microparticles and microrods and should be widely applicable to the deposition of various metals and multicomponent alloys.