Study On The Formation Mechanism And Photocatalytic Performance Of Cuprous Oxide Crystals With Different Morphologies

In this paper,different mixed reducing agents were used to prepare Cu₂O crystals with various morphologies such as octahedral,octahedral cube and rhombic dodecahedron polymorphs,hexagonal dendrites and skeletal crystals under hydrothermal conditions.By adjusting the experimental parameters,The controllable preparation of Cu₂O crystal morphology is basically realized.The growth mechanism of various morphologies is analyzed from the characteristics of different surface nets of Cu₂O crystals and crystal preparation conditions.The relationship between the morphology and properties of Cu₂O crystals was preliminarily explored.Using 1:1 mixing of glutamic acid and glycerol as the reducing agent and NaOH as the additive,the morphology of Cu₂O crystals was adjusted by changing the amount of NaOH and the concentration of the solution,and octahedral and hexagonal dendrites were obtained under hydrothermal conditions.Cu₂O crystals.The Cu²⁺/glycerol complex ion is selectively adsorbed on the（111）surface network,which reduces the growth rate of the crystal along the[111]direction;the C=O bond in glycerol is adsorbed on the surface of the carrier in the form of bidentate,It promotes the deep oxidation process.In the solution system,the concentration of the solution at the apex of the Cu₂O crystal is greater than the center of the crystal face,and the growth rate is fast,which promotes the growth of the crystal along three perpendicular principal axis directions to form hexagonal dendrites.Using 1:1 mixing of glutamic acid and sorbitol as reducing agent and NaOH as additive,Cu dendrites and 4 kinds of Cu₂O crystals with different morphologies were prepared under hydrothermal conditions,including octahedrons,crystal faces and crystal edges.Octahedral rhombohedral dodecahedron polymorphs with triangular pits,octahedral cube polymorphs with hollow crystal faces,and octahedral rhombohedral dodecahedral polymorphs with large areas and ridges missing.The threonine hydroxyl pair on carbon two and carbon three of sorbitol coordinate with Cu⁺in the crystal structure to form a complex complex.The complex forms Cu₂O in a high-temperature solution,and Cu²⁺is reduced to Cu⁺in a large amount in the solution.The corners grow rapidly and the crystal faces grow slowly,leading to the formation of Cu₂O skeletal crystals.Using the mixture of EDTA and glucose as the reducing agent and NaOH as the additive,octahedron,hexagonal dendritic crystals,octahedral rhombic dodecahedron polymorphs with triangular pits on crystal faces and crystal faces with cavities on crystal faces were prepared by hydrothermal method.The octahedral cube rhombohedral dodecahedron polymorphism,the octahedral rhombic dodecahedron polymorphism with large areas of incomplete crystal faces and crystal edges,and the octahedron and hexagonal dendritic crystals with slightly etched crystal faces are 7 different crystal morphologies.The morphology of the product is adjusted by adjusting the NaOH concentration and the amount of EDTA.Excessive NaOH will dissolve Cu₂O crystals to produce different morphologies;EDTA is easily coordinated with the unsaturated Cu⁺on the crystal surface,changing the solid-liquid The equilibrium state of the interface promotes the Oswald ripening of the crystal face.The growth-etching mode of the crystal and the Oswald maturation effect of the crystal plane together lead to the formation of the Cu₂O crystal morphology of the crystal plane cavity.Using 4 kinds of Cu₂O with different morphologies as catalysts,the methylene blue solution was degraded under visible light irradiation,and the photocatalytic degradation rate of Cu₂O with different morphologies was tested:the crystal face has hollow octahedron cubic rhombohedral dodecahedron polymorphism degradation rate 85%>The degradation rate of hexagonal dendritic crystal surface is 73.5%>the degradation rate of octahedral cubic skeletal crystal surface is 73%>the degradation rate of octahedral crystal is 42.1%.Dendritic Cu₂O crystals have a larger specific surface area than single crystals,have strong adsorption,can better inhibit the recombination of electron-hole pairs,have more active centers,and improve the photocatalytic performance of the crystal.