Nano Research

Article Title

Bromide ion mediated modification to digestive ripening process: Preparation of ultra-small Pd, Pt, Rh and Ru nanoparticles


digestive ripening, ultra-small nanoparticles, halide ions, catalysis


Nanoparticles of catalytically important transition metals, such as Pd, Pt, Rh,and Ru have been prepared by the well-known “digestive ripening” (DR) and“modified digestive ripening” (mDR) methods. In the traditional DR process, apolydisperse colloidal dispersion is refluxed in the presence of a surface-activemolecule, such as alkanethiol. The mDR method involved a small modificationin the procedure, wherein refluxing was performed with an alkanethiol anda tetra-alkylammonium bromide surfactant. This minor modification led to adramatic change in the final particle size distributions, giving access to nanoparticlesin the <3 nm size regime; this was not possible with the traditional DRprocess. Bromide ions, which are present during refluxing, proved to be animportant ingredient in the modification process. These bromide ions are revealedto act as etchants, resulting in ultra-small nanoparticles. All transition metalnanoparticles investigated displayed catalytic activity in the reduction reactionof p-nitro phenol. Pd nanoparticles, synthesized by a modified digestive ripeningmethod, exhibited the best catalytic activity among the systems investigated.

Graphical Abstract


Tsinghua University Press