Carbon-based Electrocatalysts for Oxygen Reduction Reactions

Department of Energy EngineeringDue to the rapid industrial development and growing human population, along with the increase in energy demand, the global energy consumption has been accelerating at an alarming rate. At current consumption rate, global energy exhaustion will become inevitable. Fuel cell draws tremendous attention as the upcoming alternative energy source. Because fuel cells are eco-friendly process to produce electricity, water and heat only with no pollutant or toxic by-product, many researches are now focusing on cost down and efficiency up fuel cells. The challenging and current bottleneck lies in the sluggish oxygen reduction reaction (ORR) kinetics on the cathode that significantly limits the efficiency and performance of the fuel cell device. Platinum is the most widely studied noble metal as electrocatalyst. However, it is too expensive and limited reserve in earth. Therefore, exploring new electrocatalysts with enhanced ORR activities and stabilities for the replacement of this costly noble metal with non-platinum alternatives is highly warranted and is of paramount importance to commercialize fuel cells as well as for other renewable energy applications. In this thesis, I explained with a brief overview of ORR in fuel cells and then I introduced my research results, including platinum incorporated multi-walled carbon nanotubes, heteroatom doped graphene and iron encapsulated polymers related with oxygen reduction reaction in both acidic and alkaline medium. Furthermore, these catalysts showed excellent electrocatalytic activities toward ORR with a high selectivity, good tolerance to methanol crossover/CN and SCN poisoning effects, and good long-term cycle stability.ope