Controllable Structure Of Cobalt Based Nanocomposites And Their Electrocatalytic Performance In Alkaline Medium

With the increasingly serious environmental problems and global energy demand is increasing,petroleum gas,coal and other non-renewable energy and unable to meet the needs of human beings,therefore,development of clean and sustainable energy become a top priority.In recent years,new clean energy technology in metal-air battery has attracted the attention of the researchers.However,due to the slow kinetics and high reaction energy barrier of oxygen reduction reaction and oxygen evolution reaction,these energy devices are hindered in practical application.To accelerate the kinetics of reaction and lower ORR and OER barriers,now is an urgent need to solve the problem.At present,some precious metals such as Pt base show excellent electrocatalytic performance of ORR and OER.However,high cost,shortage of resources and poor stability make it unable to be applied in large-scale practice.In recent years,cobalt based nanocomposites in transition metals have been widely studied because of their low cost,high catalytic activity and easy to obtain.However,cobalt-based nanomaterials still have disadvantages such as poor electrical conductivity,small specific surface area and unclear role of active sites,which limit their development.By forming nano-composite materials with two-dimensional materials such as graphene and black phosphorus,part of the shortcomings can be overcome and its electrocatalytic performance can be improved.However,the current preparation methods of cobalt-based nanocomposite materials are usually cumbersome and time-consuming,which results in its limited application in the field of catalysis.Therefore,it is of great research value to strip bulk phase materials into thin layers and load transition metal nanoparticles on them at the same time to increase the conductivity of materials and improve the catalytic performance.In this paper,a series of cobalt-based/2D materials were prepared by adjusting the electrolysis time using simple two-electrode electrochemical cathode stripping and three-electrode electrochemical cathode stripping methods respectively,and their electrochemical properties were studied.On the one hand,a lot of research work has been done on the preparation of graphene and black phosphorus composite materials,and the preparation conditions have been optimized by using simple and novel methods.On the other hand,the electrochemical oxygen reduction and oxygen evolution properties of the prepared materials were investigated and the catalytic principle was analyzed.The specific work is divided into the following parts:1.Using simple electrolytic solvothermal method to prepare Co/G,and applied to the electrocatalytic oxygen evolution and oxygen reduction reaction.By adjusting the different electrolytic time to regulate the content of Co in the sample.the result shows that adjusting the reaction time is very important to the reaction performance in addition.We also explored the influence of catalyst valence on catalytic performance.The results show that OER reaction is promoted by Co³⁺and ORR reaction is promoted by Co²⁺,and the catalyst has excellent catalytic activity when the electrolysis time is controlled at 10 h.2.Co-Fe/G catalyst was synthesized by electrochemical cathodic stripping method and solvothermal method.A series of characterization data confirmed that there was a strong electronic interaction between iron and cobalt.Building on the first part of the work,with the incorporation of iron,more Co³⁺was generated,and the active site of OER reaction was increased,thus improving the catalytic activity of the material.3.Co-Fe/BP catalyst was synthesized used electrochemical cathodic stripping method and solvothermal method by optimizing the electrolysis time.Build on the previous work with the addition of iron,part of the lone electron pair on phosphorus is transferred from cobalt to iron.Under the no light condition,the active site is concentrated on cobalt,and iron plays the role of auxiliary catalyst.Under the light condition,iron promotes the response of black phosphorus to light,thus improving the electrocatalytic oxygen evolution performance of the material more Co³⁺was generated,and the active site of OER reaction was increased,thus the catalytic activity of the material was improved.