Preparation And Performance Research Of Non-precious Metal Doped Carbon Based Oxygen Electrodes

In recent years,the development of clean and efficient alternative energy sources to solve the increasingly severe energy crisis and environmental pollution has become an irresistible trend.Fuel cells,water splittings and metal-air batteries are now considered to be very promising approaches to energy conversion and storage.One of the most common problems facing these devices is the sluggish oxygen reduction reaction(ORR)kinetics and oxygen evolution reaction(OER)kinetics at the cathode.Precious metal catalysts(such as Pt,Ir)have seriously hindered the commercialization of these high-energy devices due to scarcity and poor stability.Therefore,it is highly desirable but still challenging to create highly active,stable and low-cost catalysts with superior activity even over precious-metal catalysts.In this paper,the high-efficiency oxygen electrode catalysts were prepared by high-temperature carbonization using novel precursors such as the new covalent organic polymers(COPs)and zeolite imidazole frameworks(ZIFs).Then its electrocatalytic performance was studied.The main research contents are as follows:1.COPs as a new exciting type of porous material with the high specific surface area,high porosity,excellent chemical stability and adjustable architectures have aroused great interest in the electrochemical field.Briefly,COPs was synthesized with meso-tetra(p-bromophenyl)porphine and 3,8-dibromophenanthroline as monomers by the Yamamoto reaction,followed by bimetallic Fe/Ni doping.Then,Fe/Ni co-doped COPs composites were carbonized under the assistance of SiO2,converting into CCOPTDP-FeNi-SiO2 catalyst with excellent ORR/OER activity.In alkaline media,CCOPTDP-FeNi-SiO2 catalyst exhibits the best ORR activity with an onset potential of 0.990 V and a half-wave potential of 0.890 V.The CCOPTDP-FeNi-SiO2 catalyst reaches a current density of 10 mA cm-2 at an overpotential of 0.310 V.Furthermore,the CCOPTDP-FeNi-SiO2 catalyst shows excellent stability,high electrochemical surface area and the oxygen electrode activity parameter ?E value is as low as 0.650 V.2.ZIF-8,which is constructed by bridging metal atoms and ligands into 3D ordered crystal frameworks with rich micropores,high surface areas and excellent chemical stability,provide a good platform to design ORR catalyst.The ZIF-8@ZIF-8-Fe precursor was prepared by the water-methanol two-solvent method,then the CZIF-8@ZIF-8-Fe catalyst with porous structure was obtained by high temperature carbonization.In alkaline media,CZIF-8@ZIF-8-Fe catalyst exhibits the best ORR activity with an onset potential of 1.000 V and a half-wave potential of 0.880 V.Furthermore,the CZIF-8@ZIF-8-Fe catalyst shows low H2O2 yield,high electrochemical surface area,excellent stability and strong methanol tolerance.