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42446-G10
Pt-Fe Nanoparticle-Based Electrocatalytic Membranes
This program aims at understanding the structure-catalytic property relationship using PtFe nanoporous membranes as the model systems. Our data from last year indicated that although the synthesis of PtFe alloy particles are feasible using Pt-Fe2O3 core-shell nanoparticles, the final products of the ensembles of core-shell nanoparticles formed bulk solid with granular features. Such solid structures are not optimized for examining the catalytic property because of their relative low activity. During the past funding year, our group has focused on the development other platinum alloy and bimetallic nanoparticles, those alloys that are expected to show high performance in oxygen reduction reactions in particular. We have succeeded in making several PtNi alloy nanoparticles and platinum on gold nanostructures.
Nanoparticles of platinum-nickel alloys have been made in non-hydrolytic solutions of octylether using a colloidal synthetic approach. We have observed an interesting crystal phase behavior in these Pt-Ni alloy or bimetallic nanoparticles. To be specific, while the bulk alloys between platinum and nickel can exist in solid solution in almost all Pt/Ni ratios, the platinum nickel nanostructures are only stable as alloy forms in limited compositions within the low temperature range (< 300 °C). Among these compositions, Pt3Ni has shown the highest electrocatalytic activities in direct methanol oxidation.
We have explored the formation of platinum on gold nanoparticles as an alternative way to control the composition and structure of the catalysts. In this work, we used a sequential approach similar to those developed for making Pt-Fe2O3 core-shell nanoparticles. The synthesis has been quite successful and we can obtain several bimetallic Pt-Au nanostructured catalysts. Platinum on gold nanoparticles have recently been shown to be effective in hydrogenation reaction and proposed to be active towards oxygen reduction in hydrogen fuel cells. We have tested the performance of such catalysts and, unfortunately did not observe improved performance in oxygen reduction reactions. Nevertheless, this proof-of-the-concept synthesis suggests that the heterogeneous structures should be quite feasible for Pt-based bimetallic structures and the approach can be a generic method.
This grant partially supported a second-year Ph. D. graduate student working on the above topics during the past year. It has also served as a vehicle for me to work with local high schools and through American Chemical Society Project SEED program. This ACS-PRF grant has played a very important role in getting me started in this reviving area of electrocatalysts. The grant, though small in size, legitimizes my efforts in creating a new research direction on electrocatalysts based on several types of nanoparticles previously developed for magnetic applications. I believe that receiving this ACS-PRF grant may have made it easier for me to compete for other grants, as it not only gives my group the flexible support for generating essential preliminary data but also the kind of critical recognition in a new field. It is worthwhile to mention that this grant has partially contributed to a large effort of our department in setting alternative energy as a strategic research direction and gaining support from the University of Rochester. Since last year, the University of Rochester has invested about a quarter million dollars to renovate new research space and to set a fuel cell testing laboratory hosted in our department. Such facility has no doubt will help my group in developing new classes of electrocatalysts in the future.
