Preparation Of Black Phosphorus-based Composite Material And Its Electrocatalytic Performance Toward Oxygen Evolution

Oxygen evolution reaction（OER）is an important speed control reaction in the energy conversion and storage processes of water splitting to produce hydrogen and metal-air batteries.Therefore,the development of efficient OER catalysts is of great significance for new energy applications.At present,OER catalysts are mainly precious metal catalysts such as Ru and Ir.The development of non-precious metal and non-metal OER catalysts with excellent performance and low price has been a research hotspot in recent years.Black phosphorus has a graphite-like structure,and its wrinkled honeycomb layered structure has a higher specific surface area than other two-dimensional nanomaterials,and provides abundant active sites for the reactants.Therefore,it has been applied in the field of catalysis in recent years.However,the phosphorus atoms on black phosphorus have active lone pairs of electrons,which leads to their easy oxidation and degradation,which in turn leads to poor stability of black phosphorus,which greatly limits the wide application of black phosphorus-based materials.In order to solve the problem of the stability of black phosphorus,this paper improves its stability from two aspects:（1）Introduce transition metal to interact with active phosphorus atoms on black phosphorus to form transition metal phosphide on the surface of black phosphorus;（2）Combine black phosphorus or its quantum dots with highly conductive graphene to construct a heterostructure composite,and then transfer the active lone pair of phosphorus atoms to the graphene to improve its stability.The specific research results are as follows:1.The NiP/BP composite was prepared by a simple electrolysis-solvothermal method,and the OER performance of the catalyst was investigated.In the electrochemical preparation process,the black phosphorus of the cathode is stripped into black phosphorus nanosheets,and the nickel anode gradually dissolves to form ions,and finally the Ni P/BP composite is synthesized by solvothermal.The electrochemical test results show that the Ni P/BP-10h catalyst has the best OER activity.The overpotential at 10 m A cm^-2 is 341 m V,and the Tafel slope is 83 m V dec^-1.It has the best stability and superiority.Conductivity.XRD,SEM,XPS and other characterization results show that the nickel phosphide/black phosphorus composite is obtained by this preparation method,and the electron transfer between P and Ni is the reason why the Ni P/BP composite exhibits better stability.In addition,the effects of electrolysis time,electrolyte type,and electrolyte concentration on the OER performance of Ni P/BP catalysts were systematically studied.2.Cobalt and nickel have similar electronic structures and many valence states,and are also commonly used catalysts for OER.Therefore,on the basis of the first part of the work,transition metal cobalt was introduced to black phosphorus to construct a Co P/BP composite material for OER reaction.In this part of the work,the Co P/BP composite material is still prepared by the electrolysis-solvothermal method.The electrochemical test results show that the Co P/BP-30 heterojunction prepared under a voltage of 30 V exhibits the best OER catalytic activity and stability,and the overpotential is only 300 m V at a current density of 10m A cm^-2.It is 41 m V lower than the potential obtained on the Ru O₂ catalyst,and the Tafel slope is 56 m V dec^-1.The characterization results show that the cobalt phosphide/black phosphorus heterostructure composite catalyst synthesized by this method exhibits better OER performance due to the synergistic effect of cobalt phosphide and black phosphorus nanosheets.The content of Co increases with the increase of electrolysis voltage.Cobalt phosphide will form cobalt oxide in the OER reaction process,and act on the OER reaction together with cobalt phosphide.3.In order to expose more active sites of black phosphorus,in this part of the work,we will prepare black phosphorus quantum dots by mechanical grinding and ultrasonic pulverization.Black phosphorus quantum dots will be more exposed due to their larger specific surface area.Many active sites.In order to prevent black phosphorous quantum dots from reducing their activity and stability due to excessive oxidation,they were loaded on graphene prepared by electrochemical cathodic exfoliation to construct BPQDs-G composites.In addition,the OER performance of composite materials can be adjusted from two aspects:（1）Load BPQDs into graphene carriers with different calcination temperatures（60℃,300℃and 800℃）to construct composite materials;（2）BPQDs with different concentrations Load on graphene to build composite materials.The results show that the OER performance of the non-metal composite catalyst obtained by loading BPQDs with an absorbance of 2.1 to graphene calcined at 800℃is the best,with an overpotential of 341 m V at 10 m A cm^-2,which is comparable to the overpotential of the noble metal oxide Ru O₂（341 m V）Equal,indicating that BPQDs have excellent OER performance.