Model evaluation of proton exchange membrance fuel cell performance utilizing platinum catalyst

Abstract

Designing a more efficient and cost effective proton exchange membrane fuel cell (PEMFC) is highly required. This is due to its enormous potentials in portable and transportation applications. The main component that needs to be optimally design to achieve this purpose is the catalyst layer (CL) of the fuel cell. Recent studies have focused in effective utilization of the precious metal, usually platinum (Pt) which is used as the most effective catalyst so far. Two ways are employed to achieve this. Firstly, is by reducing the Pt mass loading and secondly is reducing the Pt to smaller nanoparticles to get more access surface area for the reacting fuel while at the same time reducing the overall cost of the system. Despite several experimental, complex model and simulation studies, simple ways of studying more effective utilization of the Pt catalyst are still inadquate. As a result, a simple model is developed by combining the effects of Pt catalyst particle size, Pt mass loading and Pt/C ratio in order to determine their influence on PEMFC performance. This was done by modeling the CL in the low current density of the fuel cell polarization curve only using the well known Butler-Volmer kinetics. The influence of nanoparticles of diameters between 1.5 nm to 6.5 nm, Pt mass loadings (0.4 mgPt/cm2, 0.35 mgPt/cm2, 0.05 mgPt/cm2 and 0.03 mgPt/cm2) and Pt/C ratio are examined. It is observed that the reduction in particle size increased the PEMFC performance. Furthermore, reduction of Pt mass loading increased the performance to certain limit of around 0.03 mgPt/cm2 loading. Supporting the Pt on carbon helped to reduce the amount of Pt used while improving fuel cell performance. The results are compared with other experiment and model findings. An important feature of this simple model suggests that it can be used to evaluate PEMFC performance without performing highly complex model calculations.