Break | AIChE


The increase in demand for clean energy sources has put renovated interest in fuel cells and metal-air batteries as alternatives to current technologies for electrification of mobile and stationary devices. As a potential solution to this problem, this project aims to use Fe-Kudzu catalysts as the cathode electrode in an aluminum-air battery. The oxygen reduction reaction (ORR) that happens on the cathode electrode of these devices poses one of the major challenges to be overcome before these technologies are commercially viable. The standard catalyst materials used for the ORR are based on Platinum (Pt) supported on carbon. Given its limited abundance and high cost, Pt is not an economically viable option for this purpose. Kudzu is a vine that was introduced in the 50’s and 60’s as erosion control in several southern states, but as an invasive species it does not have a natural predator to contain its accelerated dispersion, posing major problems to the ecosystem and native plant species. We have developed an ORR catalyst based on iron (Fe) that uses biomass from Kudzu leaves as the precursor for the carbon support.

The Fe-Kudzu catalysts are synthesized after a pyrolysis at 900 oC under an inert atmosphere. This relatively low temperature allows the formation of active catalytic centers for the ORR but the current density outputs obtained from this material do not meet the required values key for their use in the fuel cell or metal-air battery. In this work, we explore the addition of KetJen Black, a highly electron conductive carbon species, to the biomass-based catalyst before the pyrolysis step, to evaluate its effect on the diffusion limiting current density values. Catalytic activity is quantified by a Rotating Ring Disk Electrode Experiment (RRDE), carried out in a 3-electrode cell using 0.1M KOH electrolyte.