Modification Of Sawdust-based Biomass Activated Carbon Enhances Super Capacitor / Electrocatalytic Performance

Biomass resources are extremely widely distributed in China,but a large amount of biomass resources have not been effectively used,which not only caused a waste of resources,but also brought about environmental pollution problems.In recent years,the conversion of biomass carbonization to activated carbon technology has attracted widespread attention in the society because of its unique advantages such as high energy conversion efficiency,low pollution and convenience and efficiency.Biomass activated carbon has a developed pore structure,extremely high specific surface area,excellent electrical conductivity and stable physical and chemical properties,so it is widely used in many fields,such as super capacitor electrode materials and electrocatalytic materials.In this paper,sycamore wood chips are used as biomass raw materials,and activated carbon samples are prepared by chemical activation method.The optimized samples are obtained by characterizing and screening the activated carbon samples.Applied to materials,the conclusions are as follows:（1）Taking sycamore wood chips as raw materials and potassium hydroxide as an activator,three sets of single-factor experiments were adopted to study the effects of three process parameters,activation temperature,activation time and alkali-material ratio,on the specific surface area and specific capacitance of sycamore wood chips Finally,the optimal preparation conditions are as follows:activation temperature 800℃,activation time120min,alkali-material ratio 1:3.Under this condition,the PC specific surface area of the activated carbon sample reached 2498.1m²/g,the average pore size was 2.23nm,and the total pore volume was 1.34cm³/g.The performance of the supercapacitor was tested in 6M potassium hydroxide solution,and the specific capacitance was 176.8F g^-1at a current density of 1A g^-1,and the rate performance at a current density of 20 A g^-1was75.05%,After 10,000 cycles,the amount of capacitance remains 91.1%.It is concluded that PC has excellent cyclic voltammetry performance and impedance performance.（2）Further doping cobalt and nitrogen elements on PC to improve the performance of the material’s supercapacitor.After successfully introducing cobalt and nitrogen elements,electrode materials with Co-Nx and Co-Cx active sites were obtained.The PC-Co N-2electrode material has a specific capacitance 330.2 F g^-1under the condition of 1 A g^-1,the rate performance at 20 A g^-1 current density is 57.66%,and after 10,000 cycles,the capacitance retention is 90.8%.Finally,it is concluded that the PC-Co N-2 electrode material has extremely excellent impedance performance,cyclic voltammetry performance and specific capacitance,and is far superior to PC.（3）Further doping the iron and nitrogen elements of PC to improve redox activity,the obtained catalyst PC-Co N-2 material has good ORR（oxygen reduction reaction）activity(initial potential-0.03 V,half-wave potential-0.10 V And the limit current 4.2 m A cm^-2),methanol resistance and stability,its electrocatalytic activity even exceeds commercial Pt/C electrode materials.