Modelling boron nitride nano-structures as catalysts in fuel cells

Abstract

The dissociation of O2 and HO2 are important reactions that occur at the cathode of fuel cells and require catalysts to proceed. There is a need to replace the presently used platinum catalyst with less expensive materials. Modelling has been used to identify potential two-dimensional catalysts such as boron- and nitrogen-doped graphene. Here, the possibility of boron nitride nano-ribbons and nano-tubes which do not require doping are considered. Density functional calculations are used to show that O2 and HO2 can bond to zig–zag and armchair boron nitride nano-ribbons and nano-tubes. The bond dissociation energies (BDEs) to remove an O and an OH from O2 and HO2 bonded to the boron nitride ribbons and tubes are calculated and are a measure of the catalytic effectiveness of the boron nitride structures. The results show that both the zig–zag and armchair boron nitride ribbons could be a catalyst for HO2 dissociation but not O2 dissociation. However, zig–zag boron nitride nano-tubes are shown not to be effective catalysts for the dissociation of O2 or HO2. An armchair boron nitride nano-tube is shown to have a very low BDEs to remove OH from HO2 bonded to it and could be an affective catalyst.