The Study On Preparation And Performance Of Molasse-based Nitrogen-doped Porous Carbons

Porous carbon is a porous material.Because of its high specific surface area and developed pore structure,it can be widely used as electrode materials in supercapacitors.Cane molasses is a waste containing high carbon during the production of sugar products.The study shows that it can be used to prepare porous carbon.However,several critical factors limited its application,such as the poor hydrophilicity,large internal resistance,low electrical conductivity and low capacitance.In recent years,heteroatom-doped porous carbon,especially nitrogen-doped porous carbon,can be used as electrode materials for supercapacitors due to its good surface activity,high chemical stability,adjustable pore size structure,large total specific surface area and high conductivity.In this paper,nitrogen-doped porous carbon was prepared by KOH activation method using cane molasses as raw material and different nitrogen-containing substances as nitrogen dopants.The characterization and electrochemical properties of nitrogen-doped porous carbon prepared under different conditions were studied.1.Nitrogen-doped porous carbon was prepared by high temperature activation using cane molasses as carbon source,C3H6N6 as nitrogen source and KOH as activator.The effects of reaction time,reaction temperature and nitrogen doping impregnation ratio on the morphology,pore size and electrochemical properties of nitrogen-doped porous carbon were studied.The optimum reaction conditions were as follows:reaction temperature was 700°C,reaction time was1.5 h,and doping impregnation ratio was 1:2:4.The nitrogen content was 7.74%,the total specific surface area was 2495.8 m² g^-1,the total pore volume was 1.3 cm³g^-1,the average pore size was 2.1 nm,and the specific capacitance was 285.40 F g^-1.At a current density of 5 A g^-1,the capacitance remains about 90.4%after 500 cycles.2.With cane molasses as carbon source,CO（NH2）2 as nitrogen source and KOH as activator,nitrogen-doped porous carbon with different reaction time,reaction temperature and nitrogen doping impregnation ratio was prepared by high temperature activation pore-forming method.When the reaction temperature was 700°C,the reaction time was 1.5 h and the nitrogen doping impregnation ratio was 1:3:3,the nitrogen-doped porous carbon had the best performance.The nitrogen content is about 5.09%,the total specific surface area is 2703.62 m² g^-1,the total pore volume is 1.5 cm³ g^-1,the average pore size is 2.3 nm,and the specific capacitance is 326.90 F g^-1.At the current density of 5 A g^-1,the capacitance rate remains at 92.3%after 500 cycles.This study shows that cane molasses-based nitrogen-doped porous carbon has high specific surface area and good wettability,and it can also be used as electrode materials for supercapacitors in the field of energy storage.The research results on the preparation of cane molasses-based nitrogen-doped porous carbon materials proposed a new method to prepare heteroatom-doped porous carbon materials from sugarcane molasses by using different nitrogen-containing substances as nitrogen sources and KOH as activator,which provided a new route for the application of porous carbon materials in electrode materials and adsorbents.In addition,the conversion of cane molasses,the by-product of sugar enterprises,into nitrogen-doped porous carbon materials can not only solve the problem of the disposal of by-products in the production of sugar products,but also directly apply the by-products generated in the production process to the next process to produce nitrogen-doped porous carbon materials,and then sell them to the market to achieve turning waste into treasure,which is also in line with the concept of sustainable development of green economy.