Defect Modification And Electrochemical Properties Of Porous Betel Nut Based Carbon Materials

Widely biomass resources on the earth are not used effectively,which may lead to waste of resources and environmental pollution.Therefore,the utilization of biomass has attracted great attention due to its advantages of high structure controllability,simple operation and high conversion efficiency.In this paper,betel nut-derived carbon-based porous material was prepared and the effect of preparation technology on capacitance performance was studied.A series of three-dimensional porous activated carbons were prepared by activation pyrolysis at 600-900℃with betel shell as precursor and potassium hydroxide as activator.The effects of activation temperature on the porous structure of the materials,the atomic conditions on the surface and the electrochemical properties of the materials in 6 mol/L KOH electrolyte were investigated.The results showed that a large number of K₂CO₃nanoparticles were produced by activation with potassium hydroxide,and the pores were further formed when the temperature increased.The specific surface area of the prepared activated carbon（BN）gradually increased from 599.9 m²/g at 600℃to2005.9 m²/g at 800℃.However,the specific surface area decreased when the temperature rose to 900℃.Secondly,in the alkaline electrolyte,the specific capacitance is as high as 257F/g at 800℃at the current density of 1 A/g.It was found that the mass specific capacity increased first and then decreased with the increase of temperature.Further nitrogen doping of BN was carried out to improve the performance of the material,and a set of technological processes were successfully prepared to nitrogen doped three-dimensional porous carbon（BN-K-A）material.The material exhibits a specific surface area of 2333 m²/g and a rich three-dimensional tubular porous structure,in which the nitrogen content is 2.76%.The mass specific capacitance of BN-K-A at 1A/g current density is 348 F/g,which is 73.8%higher than that of the contrast sample BN-K（257 F/g）.Even under high current density,the quality of the BN-K-A specific capacitance is 252 F/g@20 A/g,show a good ratio of performance,when using BN-K-A as electrode materials assembly button super capacitor（SC）,SC quality specific capacitance of 77 F/g（1 A/g）and under the current density of 10 A/g after10000 long circulating capacity attenuation was only 3.63%,showed that SC has excellent capacitance properties and cycle stability,and further illustrate the BN-K-A as super capacitor electrode materials with good development potential and prospects.For betel nut shell to N,P doped improve the catalytic activity of material,potassium hydroxide after activation pore-forming,produce the BN-NP2 has multiple active sites,such as C-N,C-P,etc.The BN-NP2 catalyst in 0.1 M KOH half-wave voltage of 0.81 V,limiting current density of 5.38 m A/cm²,activities and commercial Pt/C（1.00 V,0.83 V,5.60 m A/cm²）were similar,and when used as a cathode material assembled into zinc air battery,power density of 108 m W/cm².