Nafion®-stabilised Pt/C electrocatalysts with efficient catalyst layer ionomer distribution for proton exchange membrane fuel cells

Abstract

We report a facile method for the preparation of proton exchange membrane fuel cell (PEMFC) electrocatalysts from Nafion®-stabilised colloidal Pt nanoparticles (Nafion®-Pt/C), offering synthetically-directed formation of the Pt-ionomer interface and providing unprecedented control over the morphology of Pt particles on the carbon support. Electrochemical characterisation of the catalysts in aqueous acidic electrolytes using Rotating Disc Electrode (RDE) techniques revealed that Nafion®-Pt/C catalysts possessed similar specific activity and mass activity towards the oxygen reduction reaction (ORR) as commercial Pt/C catalysts, whilst requiring lower overall ionomer loadings. Combined with the near-100% utilisation measured for the Nafion®-Pt/C catalysts, this implies that Pt nanoparticles synthesised with Nafion® as a stabiliser can be ‘tuned’ to have simultaneous access to the reactant gas, the electron conducting carbon support and the proton conducting polymer electrolyte in the catalyst layer, thereby optimising the triple-phase reaction zone. By taking advantage of this bottom-up approach, which allows nanoscale control of the Nafion®–Pt–carbon interface, new opportunities exist to lower the Pt loading and the cost of the fuel cell.