Preparation And Properties Of CoSe-based Advanced Oxidation Catalysts

As a kind of advanced oxidation technology,electro-Fenton technology can continuously generate H₂O₂at the cathode,which reduces the storage and transportation costs of H₂O₂,and under the action of electrocatalysis,Fe²⁺in solution can be reused,greatly reducing iron sludge.At the same time,the electro-Fenton process has the advantages of rapid reaction,environmental friendliness,simple operation,and obvious advantages in the treatment of environmental wastewater.However,traditional electro-Fenton cathode materials face the defects of poor conductivity,low current efficiency,weak cycling stability,and low 2e^-ORR activity of cathode materials,which lead to unnecessary energy waste.Therefore,the development of high conductivity,high stability and Cathode materials with excellent 2e^-ORR activity to promote the rapid generation of H₂O₂have important scientific significance for the bottleneck problem of electro-Fenton technology.CoSe is widely used in the fields of hydrogen evolution and energy storage,as an excellent transition metal-based material.This is attributed to the unique two-dimensional layer structure of CoSe,better hydrogen affinity and higher theoretical capacity.The application of the dendritic process is rarely reported,so we prepared CoSe by hydrothermal synthesis,and systematically studied different reducing agents（including citrate,hydrazine hydrate and sodium borohydride）,different reaction times and different reaction temperatures Influence on the morphology of CoSe（including nanoflowers,nanospheres,nanoparticles）,it was found by XPS,XRD and BET analysis that the nanoflowers prepared when the hydrothermal temperature was 180?C,the hydrothermal time was 12h,and the reducing agent was hydrazine hydrate.The cobalt selenide showed the best degradation efficiency（SMT,98.3%,I=100 m A,t=120 min）,which was attributed to the best specific surface area（47.15 cm²/g）of the nanoflower-like CoSe,which guaranteed It has sufficient two-point active sites;at the same time,the unique crystal structure of CoSe effectively promotes the 2e^-ORR process and ensures the continuous generation of H₂O₂.And the EPR test and quenching experiment showed the existence of active species?OH in the electro-Fenton process.After 5 cycles,the electro-Fenton process still maintained a good degradation stability（80.1%）.However,CoSe still suffers from poor electrical conductivity,metal leaching,low current utilization efficiency,and Co²⁺leaching pollution.In order to solve the application defects of CoSe in electro-Fenton,we prepared a novel CoSe/Ti₃C₂composite nanocatalyst for the degradation of antibiotic-contaminated wastewater during electro-Fenton process.In this work,we compared the effects of different ratios of cobalt selenide and titanium carbide on the electro-Fenton degradation efficiency,and found that the CoSe/Ti₃C₂composite cathode exhibited the best performance when the cobalt selenide:titanium carbide ratio was 6:1.degradation performance（SMT,96.0%,I=100m A,t=60min）.Through the rotating disk electrode test,it was found that CoSe/Ti₃C₂showed the best electron transfer number（n=2.1）after composite titanium carbide,which indicated that titanium carbide promoted the oxygen reduction activity of cobalt selenide and improved the yield of H₂O₂.Helps to promote the electro-Fenton process;impedance test shows that the excellent electrical conductivity of titanium carbide reduces the electron transfer resistance of the composite CoSe/Ti₃C₂material,thereby improving the current utilization efficiency;ICP test shows that compared with pure CoSe,Co²⁺leaching after loading titanium carbide The rate was reduced by 71%,which was attributed to the anchoring effect of a large number of electronegative functional groups on the surface of titanium carbide;the electron paramagnetic resonance test showed the existence of O₂^?-and?OH,which indicated that the CoSe/Ti₃C₂cathode has excellent 2e^-ORR Active and Fenton properties.TOC test showed that the total organic carbon removal rate of the CoSe/Ti₃C₂cathode was as high as 65%in the electro-Fenton process,and after 5 cycles of testing,the CoSe/Ti₃C₂cathode still retained 93.2%of the SMT removal performance.In this paper,the feasibility of CoSe with different morphologies in the electro-Fenton process was explored,and the application limitations such as metal ion leaching,narrow p H range and poor conductivity of CoSe were solved by supporting titanium carbide,and the 2e^-ORR of CoSe catalyst was improved.The activity and cycle stability provide a reference for the preparation of efficient and stable electro-Fenton composite cathodes.