Development of an Impinging Jet Microreactor Synthesis Process for Surfactant-Free Pt-Nanoparticles as PEMFC Catalyst Component

Colloidal, surfactant-free platinum nanoparticles were prepared via a self-built continuous impinging jet microreactor synthesis process in alkaline aqueous methanol solution (Co4CatTM process). In these syntheses, methanol functions as a reducing agent as well as an additional solvent. Especially the synthesis of surfactant-free nanoparticles remained challenging, and additionally, the transfer of this synthesis into a continuous process required several optimization steps. In this contribution we present highly controllable final particle sizes by adjusting process temperature, platinum precursor concentration and molar ratio of the hydroxide and platinum precursor used. The size objective of the surfactant-free Pt nanoparticles was a range of 1 - 10 nm, due to the intended application in various catalytic processes, especially as PEMFC electrocatalyst. Dynamic light scattering (DLS), zeta-potential measurements, transmission electron microscopy (TEM) and UV/Vis spectroscopy were used to monitor the particle stability over a certain period of time and study the rate of the reduction reaction in more detail. Small developments! Platinum nanoparticles, with a narrow PSD, are produced using an alkaline aqueous methanol solution (Co4CatTM process). Continuous production of these particles is achieved by utilizing high flow rates within a MicroJet Reactor (MJR). This condition limits where particle nucleation can occur, and a downstream region allows particle growth to the desired particle size. image