Preparation,Doping And Electrocatalytic Properties Of Biomass Carbon Materials Derived From Fructus Azedarach

The industrial application of new energy conversion devices,such as metal-air batteries and fuel cells can solve the problems of uneven energy distribution,unstable power output and poor continuity output of solar and wind energy.Ensure the uniformity and stability of energy transmission.It will greatly change the current situation of excessive dependence on fossil energy consumption.Now,the key factor that restricts the development of these devices is the low efficiency of oxygen reduction reaction?ORR?and oxygen evolution reaction?OER?on their electrodes.Design and preparation of highly efficient catalysts for ORR and OER is of great significance to accelerate the use of renewable energy.Some stuides show that dopped biomass-derived carbon materials can reduce the reaction energy barriers in the catalytic processes and improve the conversion efficiency of new energy conversion equipment.It is worthy of further study.In this thesis,a series of dopped carbon materials derived from Fructus azedarach were prepared to meet the need of renewable,low-cost and highly active catalysts for ORR and OER to develop the material application value of Fructus azedarach.The specific work is as follows:?1?Based on the regulation of nitrogen atom on the electronic properties of carbon materials,the ORR catalytic active sites were constructed in biomass-derived carbon structure by nitrogen doping.With Fructus azedarach as the carbon source,Fructus azedarach-derived nitrogen-doped carbon materials?FNDC?were obtained by carbonization,KOH activation,hydrothermal doping and high temperature calcination.FNDC have sheet stuctures.The activity evaluation results show that the carbon material doped with ammonium chloride as the nitrogen source?FNDC-M?has the best catalytic performance.The FNDC-M has a large specific surface area of 878 m²·g^–2,an ORR half-wave potential of 0.79 V under alkaline conditions and a limiting current density of 5.5 m A·cm^–2.The active site of FNDC-M has strong chemical structural stability and high methanol tolerance.?2?Nitrogen atom and phosphorus atoms were introduced into the structure of biomass-derived carbon materials at the same time.As a result,the elctronic peoperties in carbon stucture was precisely controlled by the auxiliary effect of phosphorus on nitrogen to achieve high-efficiency electrocatalyic materials for ORR and OER.Nitrogen and phosphorus were dopped in Fructus azedarach-derived cabon materials with different reagents as nitrogen and phosphorus sources by microwave-assisted hydrothermal method to get NPDC.When the number ratio of N to P in the structure is1.09,the material NPDC-1.09 shows the best electrocatalytic performance.Amorphous NPDC-1.09 has multi-stage pore structure and abundant edge defects.In alkaline condition,the ORR half-wave potential is 0.84 V,the catalytic stability and methanol tolerance of the NPDC-1.09 are better than 20%Pt/C.At the same time,NPDC-1.09has good catalytic performance for OER with over potential of 430 m V.The zinc-air battery assembled with NPDC-1.09 as the catalyst can charge and discharge stably for84 h at a current density of 10 m A·cm^–2.In summary,this article provides a feasible idea for the preparation of biomass-derived carbon materials,and has a certain role in promoting the development of energy conversion technology and new energy storage equipment.