The Oxygen Reduction Reaction on Nitrogen-Doped Graphene: A Density Functional Theory Study

Increased global awareness of negative implications associated with climate change fuels the search for more sustainable forms of energy generation. Fuel cells have received considerable attention due to their efficiency, reliability, and lack of emissions. However, the sluggish kinetics of the oxygen reduction reaction (ORR) remains one of the main limitations. Furthermore, current ORR catalysts use platinum, which requires a sizeable economic investment due to the high cost. Experimental work shows nitrogen-doped graphene (CN_x) catalysts operate at an overpotential similar to that of commercial platinum catalysts, but an atomic level understanding of the source of activity in these materials is still lacking. This first principles study utilizes density functional theory to model the elementary steps of the ORR on CN_x materials to understand the structure-activity relationship of these materials. This study explicitly includes the role of water through inclusion of an ice-like water layer. We will discuss the impact of water on the derived overpotential of the ORR on CN_x for comparison to previous work on the Pt(111). A first principles understanding of nitrogen-doped graphene activity in appropriately modeled environments will be important in efforts to improve the performance of CN_x materials.