Platinum is an effective catalyst for many reactions, but has the problems of low abundance and high cost.  We report on two wet chemical approaches for preparing shape controlled nanoparticles with the goal of minimizing the platinum required for these applications.  Shape control of the nanoparticles results in different surface atomic arrangements which have a significant effect on catalytic activity.  Therefore, the objective of this research is to produce nanoparticles with a variety of shapes in order to provide appropriate surface structures for promoting reactions with a minimum amount of Pt.  The first approach is to synthesize Au nanoparticles following a reported seed-mediated growth method for producing Au nanoparticles in rhombic dodecahedral, octahedral, and cubic shapes (Niu et. al., JACS, 131 (2009) 697-703). Monolayers of Pt will be deposited on the surfaces of these particles to study the effects of Au particle shape on the catalytic activity of the Pt thin films.  The second approach is to reproduce the preparation of Pt3Ni octahedral particles by replacing pure oleic acid, which is commonly used in shape control particle synthesis (see for example Zhang, J., Fang, J., JACS 131 ( 2009) 18543-18547 & Zhang, J. et al., Nano Letts. 10(2010) 638-644), with olive oil to exam the effect of other chemicals in olive oil on the particle shape formation.  In this presentation, we will show that Au nanoparticles of each shape were successfully produced after modifications were made to the originally published procedure.  First, the surfactant concentration was increased for the growth of the seeds, and second, the growth of cubic crystals exhibited far more effective shape control upon increasing the reducing agent concentration.  We also successfully produced the Pt-Ni alloy octahedral particles to some degree. This preparation may be investigated further to improve the shape control. Applications of these particles as catalysts for fuel cell reactions will be explored in the future.

Synthesizing shape-controlled nanoparticles for catalytic use

247th National Meeting (2014)

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