| At present,human society faces serious fossil energy crisis and environmental pollution,which have greatly threatened the sustainable development of human society.The reduction in fossil fuel relies on the large-scale application of electrocatalytic energy conversion and electrochemical storage equipment.At present,one of the important reactions to limit the performance of these devices-the kinetics of oxygen reduction reaction is very slow,in order to accelerate the chemical reaction kinetics of oxygen reduction reaction,some precious metal catalysts such as Pt,Pd,etc.have been developed to achieve high efficiency electrochemical reactions.But their scarcity and high prices still hinder their large-scale application.Therefore,the design and synthesis of highly efficient non-precious metal or non-metal electrocatalysts has received great attention.In this report,a series of inexpensive metal-based electrocatalysts were designed and optimized,and the activity of the materials in the conversion reaction in electrocatalytic oxygen reduction reaction was improved by structural design optimization.The main contents are as follows:（1）MOF-based catalysts:Due to the structure-activity relationship,the morphology of the material often determines the properties of the material,and the ligand of MOF also determines the morphology of the material,so we control the morphology of MOF by using different ligands.We compared 4,5-dicyanoimidazole（DCI）,terephthalic acid（H2BDC）and copper nitrate to monoligand MOF-DCI-Cu,H2BDC-Cu and dual ligand MOF-Cu,N-HCNF.Firstly,the monolithic MOF is a microcube and nanosheet structure,and due to the interaction of the two ligands,the dual ligand MOF is the morphology of the inner cubic hollow microflowers.The size is as small as one tenth of the single ligand MOF.The performance of the further carbonization of MOF proves that the catalytic performance of the dual ligand catalyst is significantly better than that of the single ligand catalyst,and the stability and methanol resistance of the dual ligand catalyst are better than Pt/C.（2）Bimetallic catalyst:We can use metal cobalt to catalyze the carbon precursor into hollow nanotubes at high temperature.We prepare the MOF precursor by hydrothermal treatment of cobalt nitrate and 4,5-dicyanoimidazole,and further carbonize to prepare the cobalt at the end.The carbon nanotubes of the particles,optimized carbonization temperature,it proves the best performance at 700oC.In order to further improve the performance of the material,we have greatly improved the performance by doping the second metal Cu,even exceeding Pt/C.Experimental and theoretical results show that there is a synergistic effect between Cu-N and Co-N.It is the main reason for the optimization of catalyst performance,because the stability and methanol resistance of this synergistic material far exceed Pt/C.The practicality of the catalyst was tested and the performance of the material of the zinc-air battery was found to be satisfactory,which proves that the material has broad application prospects.（3）Preparation of hydrogen peroxide by oxygen reduction of titanium dioxide and boron-doped carbon materials:the mechanism of oxygen reduction process is divided into two reaction paths,one is the reduction of oxygen into water,which is a four-electron process;the second is the reduction of oxygen into hydrogen peroxide,a two-electron process.Hydrogen peroxide is used in bleaching,anti-corrosion and even rocket propellants.In previous studies,it was found that titanium dioxide promotes the two-electron process of oxygen reduction.We prepared a TiO2 nanotube by hydrothermal method and then compounded with amorphous carbon to obtain TiO2@C which has excellent activity and selectivity,in order to further improve the catalytic activity and selectivity of the material,we doped boron into the material,and the selectivity and catalytic activity TiO2@BC（91%） far exceed the carbon black （CB（59%））. |
