The Application Of Heteroatom-doped Graphene In Electrochemistry

Graphene is considered as an ideal electrode material for fuel cell and supercapacitor owing to the high specific surface area and excellent electrochemical properties. However, it is prone to restack for graprhene in the process of preparation and use, and thus resulting in the decrease of the surface area as well as affecting the electrochemical properties of graphene. The incorporation of heteroatoms in the perfect hexagonal carbon can prevent the restack? create defects on the plane and energy band gap as well as speed up the charge transfer rate, and then improve the electrochemical performance. Up to now, doped with single and dual heteroatom in graphene for fuel cell and supercapacitor has been most widely studied. However, ternary-doped graphene is still rarely reported so far.In this paper, a simple two steps synthesis method was used to prepare doped boron? nitrogen and phosphorus graphene. A series of characterization tests were carried out to test the electrochemical performance. The detailed research contents are as follows:(1)The boron/phosphorus co-doped graphene aerogel was synthesized via hydrothermal and freeze-drying method using graphene oxide and boron phosphate as raw materials. The obtained boron/phosphorus co-doped graphene aerogel subsequently was pyrolysis in the atmosphere of nitrogen and ammonia. By changing the pyrolysis temperature and time, the material under different conditions was obtained.(2)The obtained boron/nitrogen/phosphorus ternary-doped graphene materials (BNPGA-1000-15) was assembled into a fuel cell oxygen reduction reaction and supercapacitor test electrode. The oxygen reduction performance of the material and the performance of the capacitor were succedent tested. The values of onset potential for BNPGA-1000-15 is only lower than commercial Pt/C 0.01 V and higher than the other materials in the 0.1 mol L-1KOH solution saturated with oxygen. In addition, the limit current density of BNPGA-1000-15 is -4.6 mAcm-2, the electron transfer number is 3.8 and the relative current retention value is 88.3% after 20000s continuous test in the 0.1 molL-1KOH solution saturated with oxygen. When the BNPGA-1000-15 material is used in the supercapacitor, the specific capacitance value is 140 Fg-1 in 6 molL-1KOH solution and 1 Ag-1 current density. The specific capacity is 133.2 Fg-1 after 2000 cycles continuous test, the retention rate of specific capacity was 95.1.