Abstract
In low temperature fuel cells, the cathodic reaction, oxygen reduction reaction (ORR), is the main rate-limited step. Normally, the kinetics of oxygen reduction reaction is very slow. For the purpose of speeding up the reaction to reach a practical usable level in a low temperature fuel cell, cathode catalysts are needed to be further investigated. Pt-based materials are the most practical catalysts currently. Because these Pt-based catalysts are too expensive for making commercially viable low temperature fuel cells, extensive research over the past several decades has focused on developing alternative catalysts. This thesis focuses on the reaction processes, and points out the key of improving efficiency. Some steps which influence the efficiency of low temperature fuel cells includes; oxygen adsorption, oxygen dissociation, protonation, charge transfer, and water desorption among others. we use the method of density functional theory (DFT) to build the nano structures including graphene, single walled and multi-walled carbon nanotube. In addition, We apply adsorption and doping methods to add the cathodic catalysts, Platinum and Nitrogen atoms into the nano structures. Then, we try to use the CASTEP platform to optimize the molecular structures during the oxygen reduction reaction process and analyze about the catalytic properties such as adsorption energy, work function, reorganization energy and rate of electron transfer. In conclusion, we obtain the improvement of catalyst in most of the selected nano structures and cathodic catalysts .