The Application Of Graphyne-based Carbon Materials In Oxygen Reduction

Oxygen reduction reaction?ORR?is an important process for both fuel cells and metal-air batteries.Traditionally,platinum?Pt?-based materials are used as electrocatalysts for ORR.However,as Pt is a kind of noble metal with high price and limited reserves,the use of Pt as catalysts will restrict the commercialization of fuel cells and metal-air batteries.Metal-free catalysts for ORR are the desired materials for low-cost proton exchange membrane fuel cells.Graphdiyne?GDY?,a novel type of two-dimensional carbon allotrope,is featured by its sp-and sp²-hybridized carbon atoms,different from the other existing carbon materials.In this paper,in order to synthesize high active GDY-based metal-free catalysts,nitrogen?N?was doped into GDY to adjust the electron structure of GDY.First,a N-doped GDY catalyst was synthesized with pyridine and NH₃ as N sources successively,expressing an electrocatalytic activity at a potential above 0.8 V similar to that of commercial Pt/C for ORR in alkaline solution and higher stability and better methanol tolerance than those of Pt/C.The high activity of PNCC should derive from the pyridinic N unit which has been demonstrated as the most efficient N doping style in carbon materials for ORR.Second,Nitrogen?N?doped carbon materials are a kind of important catalysts for many applications.Doping the non-precious metal elements into carbon-based,such as iron,cobalt,nickel,can also improve its catalytic performance.The Fe,N and GDY express powerful synergistic effect,which are all essential to improve the catalytic activity of the Fe-N-GDY catalysts.XPS characterization proved the only adding into very small amounts of iron precursor that got the enough iron doping among of Fe-N-C catalyst.The catalytic shows excellent performance both in acidic and alkaline conditions.These Fe and N co-doped GDY catalysts will have potential applications in fuel cells and other energy storage devices.