Pt-Ag nanostructured 3D architectures: A tunable catalyst for methanol oxidation reaction

Abstract

Platinum-noble metal binary nanoparticles with high surface energy and controlled size exposing high index planes represent an emerging class of nanomaterials for electro-catalytic applications. However, difficulty in the synthesis of a stable high index plane exposed nanoparticles pose a hurdle to their practical applications. Herein, we report a two-step method for the synthesis of large platinum-silver nanostructures with exposed high index facets formed by the self-assembly of small nanoparticles. In the first step, size and shape controlled platinum-silver nanoparticles are synthesized using formic acid as the reducing agent and polyvinylpyrrolidone as the surfactant. In the second step, square wave potential was applied which leads to preferential exposure of high index facets on these individual platinum-silver nanoparticles. The catalyst exhibits high electro-catalytic activity towards methanol oxidation reaction with a specific activity ∼18 times higher than that of commercial platinum/carbon and 9 times higher than commercial platinum-ruthenium/carbon catalysts. This catalyst also proves to be efficient for ethanol and formic acid electro-oxidation, which shows the potential of this catalyst in practical fuel cell applications.