Comparison of two different catalyst preparation methods for graphene nanoplatelets supported platinum catalysts

•Graphene nanoplatelet supported Pt nanoparticles synthesized via two methods.•Microwave irradiation method is used.•Supercritical carbon dioxide deposition (scCO2) method is used.•ScCO2 method gave better structured catalysts with high PEMFC performance.

In this study, we compared two facile and effective approaches which are supercritical carbon dioxide (scCO2) deposition and microwave irradiation methods to synthesize Pt nanoparticles uniformly dispersed on graphene nanoplatelets (G) having 750 m2/g surface area as the support material. The prepared catalysts were characterized by using XRD, TGA, TEM, CV and PEM fuel cell performance tests. Microwave irradiation (Pt/G1) and scCO2 deposition (Pt/G2) methods resulted in the particle sizes of 3.1–3.4 nm and 1.5–1.6 nm, respectively. Higher electrochemically active surface area and PEM fuel cell performance were obtained for the Pt/G2 catalyst. An accelerated aging test, carbon corrosion, is also applied to the catalysts and Tafel slope losses were determined. Pt/G1 catalyst resulted in 50 mV Tafel slope loss whereas no significant loss was observed for Pt/G2 catalyst after carbon corrosion test.