Preparation And Electrocatalytic Performance Of Heteroatom-doped Porous Carbon Nanobowls

Oxygen reduction(ORR)is an important electrode reaction in fuel cells and Zinc-air batteries.Due to its slow dynamic process,a catalyst is needed to accelerate the reaction.Although the noble metal ORR catalyst has high catalytic activity,it is expensive,low in storage,poor in stability and low in alcohol resistance,which greatly limits its industrial application.Carbon-based catalysts in non-precious metal catalysts are the most promised substitution of noble metal catalysts.Among them,heteroatom-doped carbon materials and transition metal-nitrogen co-doped carbon materials have attracted extensive attention due to their excellent electrocatalytic performance.This thesis has carried out research on the preparation,structure control and performance test of transition metal-nitrogen co-doped carbon materials.Heteroatom doped Carbon Nano Bowls for oxygen reduction reaction.By interface self-assembly method,nitrogen,sulfur containing carbon dots and FeCl3 on the surface of a porous carbon are clinched on the surface of porous Carbon nano bowls(CB)driven by electrostatic attraction and coordination bonding.After carbonization,a nitrogen,sulfur,oxygen,ferric multiple doping porous Carbon nano bowls were successfully prepared.The material exhibits excellent ORR electrocatalytic activity?high alcohol resistance and long-term stability due to abundant active species,multi-level pore structure and high surface area.Fe,N co-doped Carbon nano bowls(Fe-N-CB-850)for oxygen reduction reaction and Zinc-air batteries.With nitrogen-rich microporous polymerization obtained by polymerization of phenyltetramine and hexa-ketone cyclohexane and the coordination reaction of iron ions with the framework nitrogen,the nitrogen-rich microporous polymerization containing iron ions was grown in situ on the surface of CB by a one-pot method.After carbonization,we successfully obtained Fe,N?doped carbon nano bowls with high specific surface area and multi-level pore structure.The ORR activity of this material is comparable to Pt/C,and the half-wave potential is as high as(0.82 V),which is consistent with the four-electron transfer process of ORR.It was verified by acid etching that Fe2O3 embedded in CB is the main ORR catalytic active species,and the lower content of Fe-Nx species also has certain catalytic activity.As a Zinc-air battery air cathode catalyst,the Zinc-air battery assembled by this material has a discharge time of 65 h and a peak power density of 68.5 mA cm-2 at 5 mA cm-2,which is equivalent to the commercial Pt/C performance.It has certain advantages in practical applications.Bifunctional catalyst for oxygen reduction and oxygen evolution reaction(OER)-Co,N-doped carbon nano bowls for electrocatalysis.Based on the above research,Co,N-doped carbon nano bowls were successfully prepared.The ORR activity of this material is comparable to Pt/C,and OER activity is much better than Pt/C.It is found that CoO embedded in CB is both an ORR active species and an OER active species.As a Zinc-air battery air cathode catalyst,the Zinc-air battery assembled by this material has a discharge time of 75 h and a peak power density of 66.5 mA cm-2 at 5 mA cm-2,which is slightly better than commercial Pt/C.The high catalytic activity and low cost of the material lay the foundation for its application in Zinc-air batteries.