Preparation And Electrochemical Performance Of Derivatives From Carbon Nano-Onions

Carbon nano-onions(CNOs)is prepared from nano-diamond by calcination at high temperature,which has the advantages of uniform size and high purity.Carbon atoms on the surface of nano-diamond are reconstructed after high temperature annealing.By controlling the calcination temperature,highly ordered carbon nano-onions materials with completely curved,graphene-like shells can be formed.As a new carbon nanomaterial,CNOs have been widely used in electronic devices,composites,energy storage media and biomaterials due to their natural abundance,large specific surface area,good electrical conductivity and chemical stability,and high curvature structure.In this paper,the preparation method,surface structure and electrochemical application properties of CNOs and their derivatives were studied.The main research contents of this paper include the following two aspects:(1)Carbon nano-onions with different graphitization degrees were prepared by annealing nano-diamonds at different temperatures(1100?,1300?,1500?).Pt/CNOs was obtained by loading 0.5 wt%Pt on CNOs by deposition and precipitation method.The reconstruction of carbon atoms and the dispersion of metal particles on the surface of nano-diamonds annealed at different temperatures were compared,the study found that the curvature structure of the prepared carbon nano-onions and small particle size is beneficial to the stability of the metal particles on the surface of the supports,Pt/CNOs modified electrode showed superior catalytic properties.The electrochemical behavior of Pt/CNOs modified electrode was investigated by cyclic voltammetry(CV).The sensing performance of Pt/CNOs/GCE electrochemical sensor for the detection of nitrite was studied by i-t method.Compared with bare GCE electrode and Pt/graphene modified electrode,the constructed NO₂^-sensor exhibits excellent electrocatalytic detection performance with a wide linear range.The sensitivity is 241.5?A m M^-1cm^-2and the limit of detection is 0.05?M.And it has good selectivity,reproducibility and long-term stability.The electrochemical sensor based on Pt/CNOs/GCE can achieve rapid,sensitive and stable analysis and detection of NO₂^-.(2)CNOs not only has good electrical conductivity and large specific surface area,but also has high mesoporous property,which is suitable for being a high-performance electrode material for supercapacitors.Nitrogen doping of CNOs can increase its wettability,and pyridine and pyrrole nitrogen can easily improve its application performance in supercapacitors.The nano-diamond was annealed at1500?to obtain CNOs.Urea was used as the nitrogen source to obtain N-CNOs.The N-CNOs/Nickel foam electrode was prepared with N-CNOs as the active material and a series of electrochemical tests were carried out on the energy storage performance of the supercapacitor constructed by N-CNOs/Ni foam electrode.The specific capacitance,operating voltage,cycle stability and rate performance of N-CNOs/Ni foam electrode were investigated.The specific capacitance of the prepared N-CNOs/Ni foam electrode reaches 137.98 F g^-1at the current density of0.01A g^-1.It shows good stability of electrochemical cycle in 10,000 constant current charge and discharge cycle test.