Preparation And Performance Study Of Nitrogen/oxygen Co-doped Soybean Meal-based Porous Carbon

As we all know,China has enormous area and numerous natural resources,including agricultural,forestry,and animal husbandry wastes,which contribute a considerable quantity of biomass resources.However,the majority of treatment techniques for the aforementioned materials include burning or stockpiling them,which not only burns resources but additionally pollutes the environment.With continuous research,people gradually find that biomass is a promising carbon material with rich resources and sustainable access.If it is modified,it can prepare carbon materials with high added value.It can fulfill both of the recommendations and solutions of green development and the problem of energy scarcity if it is used for the storage of electricity,which is a beneficial measure.An case in point of an electrical and chemical backup system for energy that is eco sustainable,has a substantial amount of power,and is renowned for its extended service life is the supercapacitor.The efficient charge and discharge rate can be achieved by fast adsorption and release of charge on the surface of electrode material.Porous carbon has high porosity,which can strengthen the effectiveness of electricity storage by expanding the interfacial interaction between the electrode and the electrolyte.At the same time,its pore size and porosity can be regulated by different preparation conditions to obtain porous carbon materials with different pore size and porosity to meet different application requirements.In recent years,porous carbon materials have been widely studied as electrode materials with good performance.Therefore,it is very feasible to select suitable biomass materials to prepare new electrochemical energy storage equipment and explore the impact of different conditions on its performance.Biomass is cheap and rich in reserves.Consequently,it will be highly competitive to use for social production.In this study,porous carbon composites made from biomass were co-doped with nitrogen and oxygen prepared from soybean meal,a by-product of soybean oil pressing.Through continuous improvement of experimental conditions and material structure,the electrochemical performance of the porous carbon electrode materials reached a higher level.The following are the primary investigations:1.Using soybean meal as raw material and carbonizing at low temperature,the carbonized soybean meal is first obtained,and then the weakly alkaline K₂CO₃ is used as an activator to raise the temperature to 550℃～750℃to prepare nitrogen/oxygen co-doped porous carbon.A few activation factors were analyzed and examined in the context of their effect on the morphological,specific surface area,distribution of pore sizes and electrochemical performance of nitrogen/oxygen co-doped porous carbon.Finally,the experimental results showed that only when activated temperature gets650°C,then operation time was 2 hours,and the impregnation ratio was 3:1,the reaction conditions were the best.Under the optimum reaction conditions,the contents of nitrogen and oxygen atoms in BPKC-650-3 are 5.24 wt%and 11.56 wt%,respectively,the specific surface area is 1442 m² g^-1,the total pore volume is 0.77 cm³g^-1,and the average pore size is 2.12 nm.In the three-electrode system test,when the current density is 1 A g^-1,the specific capacitance of BPKC-650-3 is 313.30 F g^-1;in the blue-electric test system,when the current density is 2 A g^-1,the specific capacitance of BPKC-650-3 is reduced from 212 F g^-1 to 188 F g^-1.During a test that involved 10000 repeats of prosecute at a duty cycle,the capacitance retained 88.70%of its initial specific capacitance.2.Using soybean meal as raw material,urea as nitrogen source,and weakly alkaline K₂CO₃ as activator,in a single stage of pyrolysis activation,nitrogen/oxygen co-doped porous carbon was created.The shape,particular region of surface,pattern of pore sizes,and electrochemical characteristics of nitrogen/oxygen co-doped porous carbon were examined,and the impacts of various pyrolysis temperatures and impregnation ratios were reviewed.Depending on the empirical observations,the optimized reaction settings are:pyrolysis temperature 700℃,activation time 2 h,impregnation ratio 1:1:1.Under the optimum reaction conditions,the contents of nitrogen and oxygen atoms in BPKN-700-1 are 6.16 wt%and 12.77 wt%,respectively,the specific surface area is 2528.90 m² g^-1,the total pore volume is 1.3310 cm³ g^-1,and the average pore size is 1.95 nm.In the three-electrode system test,when the current density is 1 A g^-1,the specific capacitance of BPKN-700-1 is 351.20 F g^-1;in the blue-electric test system,when the current density is 2 A g^-1,after 10000 cycles of cyclic stability test,the specific capacitance of BPKN-700-1 is reduced from 252 F g^-1to 240 F g^-1,the retention rate of the capacitance compared with the initial specific capacitance is 95.24%,the specific capacitance of Corelli is reduced from 96 F g^-1 to92 F g^-1,and the retention rate of the capacitance compared with the initial specific capacitance is 95.83%.The cycle stability of BPKN-700-1 is slightly lower than that of Corelli,which is basically equivalent,indicating that it has excellent cycle stability.To sum up,in this essay,porous carbon co-doped with nitrogen and oxygen was created by two-step self-doping method and carbonization with one process using urea as the nitrogen source,using soybean meal as raw material and weakly alkaline K₂CO₃ as activator.After that,the related characterization and testing showed that the prepared nitrogen/oxygen co-doped porous carbon has hierarchical porous structure,outstanding conductivity and chemical stability,high specific capacitance and excellent cycle stability,which means it can be adopted as supercapacitor electrode materials.At the same time,it can also be used as a catalyst carrier in other fields such as gas separation and storage in the future,which broadens the use of biomass,and also realizes low cost,high energy efficiency and no pollution,with considerable development prospects.