The Preparation Of Graphite Phase Carbon Nitride-based Nanocomposite And Its Electrochemical Performance

As a graphitic material,g-C₃N₄ has good thermal stability and chemical stability.In addition,on the one hand,the existence of N in g-C₃N₄ can increase the wettability of electrode material in electrolyte solution and increase the contact area.On the other hand,it can offer additional pseudocapacitance.All these make g-C₃N₄ be a potential and noticeable supercapacitor electrode material.However,g-C₃N₄ exists some drawbacks,such as small specific surface area,poor conductivity,low specific capacitance and so on.To overcome these drawbacks,the paper chose g-C₃N₄ as the base materials,and composited it with other metal oxides and metal particles with different dimensions.The aim is to improve the electrochemical property of material and promote the application of g-C₃N₄ in energy storage device.The main research contents include:Dicyandiamide was used as the precursor to synthesize g-C₃N₄,and the CuO nanobelts/g-C₃N₄ composite was prepared through a chemical precipitation method.The experimental results show that CuO nanobelts grown on the surface of the layered g-C₃N₄,and the length of the nanobelts is 300-600 nm,and the width is about100 nm.The electrochemical testing results show that the capacitance of composite?39.5 F/g?increased a lot compared with g-C₃N₄?8.5 F/g?,which can be ascribed to the large specific surface area and improved electrical conductivity of composite,the large theory capacity of CuO and the faradaic pseudocapacitance effect.Moreover,the cycle test results show that the capacitance of composite remains 71.0%after cycling1000 times,which shows that the cycle performance of composite should be improved.Ag nanoparticles sol was successfully prepared by reduction method,and then composed it with g-C₃N₄ through ultrasonic assisted self-assembly method to prepare AgNPs@g-C₃N₄ composite.The composite has different pore size distributions,and the pore size is mainly focused on 1.64 nm,3.26 nm and 8.65 nm got from the aperture distribution curve,which will be beneficial to the ion transport with different size.Particularly,the composite?8.953 m²/g?has larger specific surface area than g-C₃N₄?8.605 m²/g?.In the composite,Ag nanoparticles with the size of 5 nm adhere on the surface of g-C₃N₄.The specific capacitance of composite is 28.8 F/g,which improved 4.0 times compared with g-C₃N₄.The internal resistance of the composite and g-C₃N₄ are 0.965?and 1.40?respectively,which indicate the improved conductivity of the composite.It can be ascribed to the introduction of Ag nanoparticles,which can promote the transfer of electrons in electrode materials.The capacitance of composite remains 78.9%after 1000 cycles.Urea was used as the precursor to prepare g-C₃N₄ with large specific surface area,and then the Fe₃O₄ nanorods/g-C₃N₄ composite was synthesized by a hydrothermal method.The specific surface area of obtained g-C₃N₄ and composite is 80.66 m²/g and 69.02 m²/g respectively.The g-C₃N₄ in the composite is a layer structure with curves.The Fe₃O₄ nanorods with diameter of 40-50 nm are uniformly distributed on the surface of g-C₃N₄.After introducing Fe₃O₄ nanorods,the conductivity of g-C₃N₄improved a lot and the internal resistance decreased from 1.37?to 1.02?.The capacitance of material improved evidently after the composite of g-C₃N₄ with Fe₃O₄.The capacitance of the composite is 56.7 F/g,which is 4.3 times higher than that of g-C₃N₄.It can be ascribed to Fe₃O₄ with unique one dimension nanorod structure.Moreover,the composite has excellent cycle stability,whose capacitance retains85.9%after 1000 cycles.