Synthesis Of Bimetallic Gels And Study On Catalytic Performance

The metal gel is prepared by using metal nanocrystals as structural units,reducing the metal precursor by adding a strong reducing agent,and then self-assembling to prepare a hydrogel forming a three-dimensional network structure,and then forming a metal gas condensate by freeze-drying.gum.The preparation method overcomes the agglomeration of the nanocrystals and makes the metal gel have a very high porosity,so that it has a large specific surface area,an ultra-low density,excellent electrical conductivity and thermal conductivity.The high surface area of the metal gel provides sufficient active sites for adsorption and photocatalysis,which contribute to the bulk transport of liquids and gaseous materials.The three-dimensional network structure of the metal gel facilitates rapid transfer and electron transport of the medium inside the material.Therefore,due to the unique structural characteristics of metal gels,different compositions and types of metal gels have been widely used in the field of catalysis and sensing.In this paper,the bimetallic gel was used as the research object,and sodium borohydride was used as the reducing agent.Without any other blocking agent,different morphologies and compositions were prepared by regulating the composition and proportion of the metal precursor without introducing other ligands.The composition of palladium-nickel metal aerogel and gold-platinum metal hydrogel utilizes the large porosity,surface area and more active sites of the metal gel,making it easy for medium transport and electron transfer,and fully utilizing bimetallic Synergistic effect,its application in electrocatalysis and peroxide mimic enzymes.The research content is mainly divided into the following parts:?1?Using sodium borohydride as a strong reducing agent,reducing the metal precursor of palladium and nickel without additional ligand protection,and allowing it to stand at 60°C for 3 hours after a simple one-step reduction method.A proportionally controlled Pd_xNi bimetallic alloy hydrogel was successfully synthesized.After supercritical carbon dioxide freeze-drying,a three-dimensional network structure Pd_xNi bimetal alloy aerogel was prepared.The prepared metal aerogel is crosslinked by a 4 nm spheroidal metal nanocrystal to form a three-dimensional network structure.The materials were characterized by high-resolution transmission electron microscopy?HRTEM?and X-ray diffraction?XRD?.It was proved that the prepared metal aerogel was composed of palladium-nickel alloy.The oxygen reduction reaction?ORR?performance of Pd_xNi bimetal alloy aerogel in HClO₄solution was studied.The Pd₅Ni metal aerogel exhibited excellent ORR performance and chemical stability.This electrocatalyst is a 4-electron transfer process.At the same time,Pd₅Ni aerogel also showed excellent performance in ethanol oxidation reaction.The mass activity of Pd5Ni alloy aerogel is 4.30 A/mg,which is 5.5 times higher than that of commercial Pd/C catalyst,which proves that the prepared Pd₅Ni alloy aerogel has great potential as a catalyst for cathode and anode reactions of fuel cells.?2?AuPtx bimetallic hydrogel was prepared by one-pot method using HAuCl4 and K₂PtCl₄ as metal precursors and sodium borohydride as reducing agent.It is used as a peroxide mimic enzyme to catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine?TMB?by H₂O₂ to produce a color reaction.AuPt_x bimetallic hydrogels have the advantages of relatively low cost and stability as peroxide mimic enzymes.The material was characterized by transmission electron microscopy?TEM?.It was found that the AuPtx bimetallic hydrogel is a three-dimensional network with a large specific surface area and many active sites.The effects of pH,temperature and AuPtx bimetallic hydrogel concentration on the activity of peroxide mimic enzymes were systematically investigated.AuPt_x bimetallic hydrogels have lower detection limits as peroxide mimic enzymes with linear detection ranging from 0.4 mM to 12 mM.Data support is provided for the simple,sensitive and rapid detection of hydrogen peroxide using a metal gel as a mimetic enzyme.