Research On New Catalysts For Dehydrogenation From Formic Acid And Electrode Materials For Supercapacitor

The excessive consumption of non-renewable energy such as fossil fuels has prompted people to constantly seek and develop new renewable energy and sustainable green energy storage devices.Hydrogen,as a clean renewable energy,has attracted extensive attention.On the other hand,in order to make use of unstable sustainable energy such as solar and wind energy,we need to develop sustainable green energy storage devices to store and convert them.Therefore,it is of great significance to seek and develop new hydrogen storage materials and energy storage devices to solve the current environmental crisis and energy crisis.The main purpose of this paper is to prepare efficient and stable heterogeneous catalysts for dehydrogenation from formic acid and high performance electrode materials for supercapacitor.The main research contents include the following aspects:1 Carbon nanospheres prepared by biomass were used as support to prepare heterogeneous catalysts,which was used to catalyze the decomposition of formic acid-potassium formate system to produce hydrogen.In this catalytic system,MnO_x nanoparticles play the role of adsorption of CO and can effectively prevent catalyst CO poisoning.Thus,it can improve the catalytic activity of AgPd nanoparticles.The results show that the prepared catalyst has 100%H₂ selectivity and good catalytic activity(the TOF value is 3558 h^-1).In addition,the catalytic system still maintains high activity after five runs test.2 Nitrogen-doped porous carbon?NPC?material was prepared by self-sacrificing template method.Highly dispersed AgPd nanoparticles were successfully loaded on NPC by a simple liquid phase impregnation method to prepare heterogeneous catalysts for the decomposition of formic acid-sodium formate system to produce hydrogen.The optimized catalyst Ag₁Pd₉@NPC has high catalytic activity(total TOF can reach 3000 h^-1)and 100%hydrogen selectivity for formic acid dehydrogenation.The results show that the synergistic effect between nitrogen-doped carbon nanoparticles and AgPd nanoparticles plays the key role in the effective catalytic dehydrogenation of formic acid.3 A new type of nitrogen-phosphorus double doped porous carbon?NP-HPC?was prepared by pyrolysis activation method and used as electrode material to test its capacitance properties.NP-HPC,prepared by chitosan and polyphosphoric acid,has many advantages,such as layered porous structure,high specific surface area(2933 m²·g^-1)and double heteroatom doping.The optimum NP-HPC-800 has higher specific capacitance(0.5A·g^-1 289 F·g-1),excellent magnification(10 A·g^-1 238 F·g^-1)and good cyclic stability?96%stability after 5000 cycles?in 6 mol·L^-1 KOH solution.When the power density is 183.3 W kg^-1,the energy density of NP-HPC-800 is 22.5 Wh kg^-1.The low cost and simple preparation method provides a feasible way for the preparation of heteroatom doped carbon materials by biomass precursor system.4 A new type of electrode material,cobalt nickel phosphate,was prepared by surfactant assisted self-assembly at room temperature.The prepared transition metal phosphate?SDBS-Ni₂Co₁PO₄?has amorphous and mesoporous structure and shows good electrochemical properties.The specific capacitance is 191.6 mAh·g^-1 at 0.5 A·g^-1 and142.5 mAh·g^-1 at 10 A·g^-1.More importantly,the electrode material has good cycle stability(the retention rate is 77%after 2000 charges and discharges at 10 A·g^-1).The asymmetric supercapacitor assembled by SDBS-Ni₂Co₁PO₄ and graphene has a high energy density(36.5 Wh kg^-1)in 2 mol·L^-1 KOH electrolyte.This work provides a simple and green method for the preparation of cheap transition metal phosphate as high efficiency electrode material.