Study On Preparation And Electrocatalytic Performance Of Carbon-based Atomic Catalysts

With the further development of industrialization and the continuous increase of global population,human society is facing an increasingly serious crisis of resource depletion and environmental pollution.In addition,the excessive consumption of fossil energy such as oil,coal and natural gas aggravates the increasingly serious energy crisis and environmental pollution.Therefore,the exploration and development of renewable and sustainable clean energy alternative fossil fuel has become an important research direction in the field of catalysis and energy research.At the same time,almost all of these electrochemical reactions rely heavily on the use of platinum,iridium,ruthenium and other precious metal materials to reduce the over-voltage and accelerate the catalytic reaction,while precious metal catalysts are faced with high cost,scarce resource reserves and poor cycle stability.Therefore,further development of low-cost and durable electrocatalysts to effectively promote the electrocatalysis reaction on these cathodes is still the Achilles heel of the technology,which seriously hinders its wide application.In this paper,the carbon based catalysts with low cost and excellent performance,which can replace the current commercial precious metals Pt,Ir,Ru,are studied.The microstructure of the materials is designed and controlled to expose more electrocatalytic active sites.A series of highly efficient and stable C₂N supported non noble metal zinc based single atom and zinc ruthenium double atom electrocatalysts were developed and constructed,and applied to ORR/OER/HER and other catalytic behaviors.The nature of catalytic behavior of the materials was studied by electrochemical technology and spectroscopic microscopy:1.Chitosan rich in N and C was used as carbon source and nitrogen source,and zinc chloride as metal salt precursor.The effects of different precursor chitosan content and different pyrolysis temperature on the catalyst performance were investigated.Three effective zinc monatomic catalysts（Zn-900-0.8）with high activity and high stability were prepared,and their catalytic behavior was tested by ORR/OER/HER.The results showed that the content of chitosan was 0.8g,and the pyrolysis temperature was900℃,The zinc monoatomic catalyst（Zn-900-0.8）with high loading,high activity and high stability was prepared,and the ORR/OER/HER catalytic behaviors were studied.The results showed that the ORR half wave potential of the catalyst in 0.1mol/L KOH electrolyte was 0.925 V vs.RHE,and the initial potential was 1.012 V vs.RHE,which was better than that of commercial Pt/C(E_1/2=0.864 V,E_onset=0.986 V).When the current density is less than 50 m A cm^-2,the over potential of the catalyst is only 328 m V,which is better than that of commercial Ir O₂.When the current density is less than 50m A cm^-2,the required over potential is 204 m V,comparable to the commercial Pt/C（35m V）and Ir O₂（73 m V）at the same current density.It can be seen that the catalyst has shown excellent performance in the test of basic ORR/OER/HER,and it has been applied to OER reaction for the first time,which provides a new idea for commercial application of electrolytic hydropower catalyst.2.Chitosan rich in N and C was used as carbon source and nitrogen source by high-temperature pyrolysis,and zinc chloride and ruthenium trichloride were used as metal salt precursor.The effects of different precursor chitosan content,different ruthenium trichloride content and different pyrolysis temperature on the catalyst performance were investigated.The diatomic catalyst（Zn Ru-850-0.9-2m L）with high activity and high stability was prepared,and its catalytic behavior was tested by ORR/OER/HER.The results showed that the content of chitosan was 0.9g,ruthenium trichloride was 2m L,and the pyrolysis temperature was 850℃,a three functional zinc ruthenium double atom catalyst（Zn Ru-850-0.9-2m L）prepared,has high loading,high activity and high stability.The results showed that the ORR half wave potential of the catalyst in 0.1 mol/L KOH electrolyte was 0.860 V vs.RHE,and the initial potential was 0.984 V vs.RHE,which was comparable to that of commercial Pt/C(E_1/2=0.864V,E_onset=0.986 V).When the current density is less than 50 m A cm^-2,the over potential of the catalyst is only 313 m V,which is better than that of commercial Ir O₂.When the current density is less than 50 m A cm^-2,the required over potential is 271 m V,comparable to the commercial Pt/C（35 m V）and Ir O₂（73 m V）at the same current density.It can be seen that the catalyst has shown excellent performance in the alkaline ORR/OER/HER test.With the aid of the synergistic effect between the two atoms of the diatomic,it provides a feasible reference for the preparation of the diatomic catalyst by the combination of noble metal and non noble metal.