Preparation And Electrochemical Properties Of Biowaste-based Doped Carbon Materials

The research and development of clean energy have become one of the most attractive topics in contemporary society.Carbon materials derived from biomass waste have been received extensively attention because of the wide applications in fuel cells and supercapacitors.The preparation of carbon materials in this way can reduce the cost of carbon materials and promote the sustainable development.This work has significant economic and environment effects.In this study,the biomass waste Triarrhena sacchariflora panicles were used as the carbon precursor.Firstly,Triarrhena sacchariflora panicles were hydrothermally treated in KOH aqueous solution.After carbonization and nitrogen doping process,the N-doped carbon material was obtained.The material C-A-N presents a 3D interconnected hierarchical porous structure,a high BET surface area(1347 m²g^-1)and effective N doped（3.83%）.C-A-N displays an excellent oxygen reduction reaction catalytic activity(E_1/2=0.83 V),along with a high stability（6%loss of current density after 10000seconds）in alkaline media.Compared to the Pt/C catalyst（20 wt%）,the catalyst exhibits a similar ORR catalytic activity and much higher stability.The C-A-N also exhibits a high specific capacitance(436 F?g^-11 at 1 A?g^-1)and excellent stability（capacitance retention of 4%after 2000 cycles）as supercapacitor electrode materials.In order to improve the oxygen reduction reaction catalytic performance of C-A-N,the biomass waste Triarrhena sacchariflora panicles were hydrothermally treated in different concentrations of cobalt acetate aqueous solution,after a one-step nitrogen doping and carbonization process,shell-core structural CoO@Co nanoparticles immobilized on N-doped porous carbon materials CoO@Co/N-C was obtained.The material C-Co0.2-N-800 exhibits an excellent oxygen reduction reaction catalytic activity in alkaline media.The E_1/2/2 of oxygen reduction reaction is 0.85 V.C-Co0.2-N-800 also displays an excellent oxygen evolution reaction catalytic activity and high stability.The overpotential measured at the current density of 10 mA?cm^-2 is only 340 mV.C-Co0.2-N-800 is an excellent bifunctional catalyst.The potential-difference between the oxygen evolution reaction current density at 10mA?cm^-2 and oxygen reduction reaction current density at-3 mA?cm^-2（ΔE）is 0.82 V.