Enhanced Catalytic Activity of Pt Nanomaterials: From Monodisperse Nanoparticles to Self-Organized Nanoparticle-Linked Nanowires

The factors affecting the catalytic activity (CA) of monodisperse nanoparticles (NPs), including size, crystallinity, shape, and high indexed facets, have been well-studied these past years; here, we report that the CA is significantly increased when monodisperse Pt near-spherical NPs are cross-linked into Pt nanowires (NWs) using two model catalytic reactions, reduction of either nitrophenol or potassium ferricyanide. In this work, monodisperse Pt NPs or NWs were prepared by using glucose as a surfactant and sodium borohydride as a reducing agent in aqueous solution at room temperature. Monodisperse Pt NPs or Pt NWs can be obtained by simply controlling the molar ratio, R, of the sodium borohydride to the platinum salt, [NaBH4]/[Pt4+]. Different types of Pt NP or NW colloids were used as catalysts in the catalytic reactions above. The results showed that the normalized rate constants of the catalytic reactions increase mildly with increasing particle size for the monodisperse Pt NPs, but they drastically increase for the Pt NWs with a similar mean size as compared with the monodisperse Pt NP colloids. It is thus expected that the large abundance of grain boundaries, generated when NPs are linearly linked into NWs, may be responsible for this enhanced catalytic activity.