Electrochemical And Gas Adsorption Properties Of Biomass Porous Carbon Materials

With the rapid development of economic and technology,following with energy shortages and environmental pollution problems.Therefore,it is an urgent task to develop clean and highly efficient renewable alternative energy sources.To solve the problem,it is necessary to develop conversion technologies and energy storage.Compared to traditional batteries,supercapacitors are a new-type potential electrochemical be able to it can charged-discharged in a matter of seconds,high power density,and good cycle stability.The performance of supercapacitors depends on its electrode materials.Carbon materials are the only electrode materials used in commercial,because of their low cost and wide sources.Due to its wide source,distribution,environmental friendliness,and renewable characteristics,biomass has been widely used for preparation of porous carbons.Biomass-derived porous carbon has a high specific surface area,a suitable pore size distribution,and a self-contained atomic doping makes it an option material for supercapacitor.The major works of this article are as follows:(1)We used a facile one-pot synthesis of biomass poplar sawdust derived nitrogen-doped carbons by using KOH as activating agent,and further explore its application in supercapacitor electrode materials.We explore the effects of carbonization temperature on the morphology,graphitization,nitrogen content,and pore size distribution of porous carbon materials(2)We tested the electrochemical properties of nitrogen-doped porous carbon materials in two-electrode and three-electrode setup in different electrolytes(acidic,alkaline,and neutral).The results indicate that NPC-750 obtained at T=750 ℃ exhibits a large specific surface area of 2149 m2·g-1,suitable pore size distribution,high graphitization degree high nitrogen content,especially the graphite nitrogen content,which leading to excellent capacitive performance.The NPC-750 shows a high specific capacitance of 362 F·g-1,capacitance retention of 76%and excellent cycling stability with a retention of 92.2%after 10000 cycles and stable coulombic efficiency of~99%.(3)To further improve the capacitance performance of carbon-based materials,the NPC/PANI composites was synthesized by in situ based on NPC-750.By optimizing the best composite ratio,we find that the capacitance retention was increased from 76%to 89.9%,exhibits a wider voltage range of 0-1.4 V than the one of 0-1 V of NPC,as well as a much higher energy density of 15.45 Wh·kg-1,which is 1.73 times of 5.66 Wh·kg-1 of NPC.The excellent electrochemical performance of the composites is attributed to the synergistic effect of the electric double-layer capacitance and Faradaic capacitance.(4)The CO2 adsorption in the NPCs was tested,the results indicate that NPC-750 exhibits extremely a high CO2 capacity of 4.21 mmol·g-1 at 273 K and 1 bar,which related to its high specific surface area and suitable pore size distribution.