Electrochemical synthesis of nanoporous platinum nanoparticles using laser pulse heating: Application to methanol oxidation

Hussein, Haytham E. M., Amari, Houari and Macpherson, Julie V. (2017) Electrochemical synthesis of nanoporous platinum nanoparticles using laser pulse heating: Application to methanol oxidation. ACS Catalysis, 7 (10), 7388-7398. (doi:10.1021/acscatal.7b02701).

Abstract

Nanoporous platinum nanoparticles (NPs) have been proposed as promising electrocatalytic materials. Routes to produce them typically consist of chemical synthesis or selective dissolution of one component of a two-component mix. Here we show that by employing a pulsed laser heating approach during electrodeposition, whereby the electrode/electrolyte interface is continually heated and cooled, NPs with a nanoporous structure can be grown directly on the electrode (boron-doped diamond) surface. Transmission electron microscopy shows the NPs to be composed of loosely packed aggregates of much smaller crystalline particles of size 2–5 nm, with the porosity increasing with increasing deposition overpotential. In contrast, electrodeposition at room temperature (RT) results in particles which show a considerably more compact morphology and fewer higher index crystal facets, as revealed by electron diffraction techniques. Pulsed heating also offers a route toward controlling the monodispersity of the electrodeposited NPs. When applied to the oxidation of methanol, the laser-heated NPs show considerably higher catalytic current densities in comparison to RT-deposited particles. The highest catalytic activity is observed for the most porous NPs produced at the highest overpotential. Interestingly, the ratio of the forward oxidative current to the backward current is highest for those particles deposited under laser-heated conditions but with the smallest overpotential. This suggests that the most catalytically active NPs may also encourage binding of residual adsorbed carbon monoxide and that a compromise must be reached.

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