Approaches to remove sufactants on metal nanoparticle surface for catalytic
Noble metal nanoparticles (Pt, Pd, Au, etc.) have attracted a lot of interest. They are promising catalysts for a bunch of chemical reactions due to their large surface-volume ratio. People have developed various approaches to synthesize noble metal nanoparticles, including ion beam sputtering, polyol process, salt reduction in aqueous solution, and so on. However, the quality from these approaches is yet needed to be improved.Organic solution synthesis has been demonstrated to be a powerful technique to synthesize monodisperse various inorganic nanoparticles. For instance, Pd nanoparticles with size control was reported to be synthesized in oleylamine in the presence of TOP. Monodisperse Pd nanoparticles were obtained (see the attached nano lett paper).
However, there is still a big disadvantage for catalysis of nanoparticles obtained by this approach, though nanoparticles of almost perfect quality can be obtained. It's the surface ligands used to stabilize the nanoparticles. For example, the TOP used to synthesize the Pd nanopaticles bond to the Pd surface very tightly, which will occupy almost all the surface sites on the particles. Such nanoparticles become less useful unless further treatment are applied to remove the surfactants.
Unfortunately, so far as we know, the best way to remove the surface surfactants is thermal annealing. The annealing, however, will lead to aggregation of nanoparticles and destroy the nanostructure for catalysis. Efficiently remove the surface ligands while keeping the nanoparticle morphology are still a big challenging today.
If anyone knows good methods to solve this problem, I would appreciate your discussion with me. I am also happy to share my knowledge on nanoparticle synthesis and applications.
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