Buckypaper-based catalytic electrode containing graphene nanoplates and ZrO2 nanorod composite to improve PEMFC performance

Abstract

Many researchers proposed the use of graphene nanoplates (GNPs), carbon nanofibers(CNFs) and metal oxide nanorods as an advanced metal catalyst support for electrocatalysis applications. In this research, Platinum (Pt) catalytic electrode was developed by using GNPs and CNFs containing ZrO₂ nanorods (buckypaper) as supporting medium and electrodeposition method to deposit Pt catalyst. Special mixed buckypapers (BPs) was developed by layered microstructures with a large porous structures of CNFs networks at the surface, as well as dense and high-conducting GNP networks as back supports. This unique microstructure led to improve Pt catalyst accessibility and mass exchange properties. The topographical features, structure, morphology and composition of the prepared film samples are characterized by AFM, XRD, FESEM and EDX. The thickness of approximately 39micrometer and a porosity of 81%, were obtained by porometer using mercury prosimetry test. Catalytic properties of Pt/BPs electrodes and MEA performance evaluations were measured using potensiostat/galvanostat and fuel cell test station based on cyclic voltammetry and single cell polarization measurements. Pt particles of about 6.66nm were uniformly deposited in porous BPs. A promising electrochemical surface area of 31.66m²g^-1 was obtained from these electrodes. The peak power density of the cell worked by BPs with ZrO₂ nanorods was 0.288 kWcm^-2, higher than 0.23kWcm^-2 measured on the cell worked by the BPs without ZrO₂ nanorods. A Pt utilization as high as 0.675gPtkW^-1 was achieved for the cathode electrode at 80◦C. Pt utilization efficiency can be further improved by optimization of the electrodeposition condition in order to reduce the Pt particle size.