Synthesis And Photocatalytic Properties Of Carbon/Ferric Oxide With Biological Sheet Structure

With the rapid development of society and the progress of light industry,more and more printing and dyeing wastewater is discharged into the ecosystem,causing irreparable damage to the human body and other organisms.Among the printing and dyeing materials,azo dyes account for a large proportion,and azo organic pollutants cannot be completely eliminated by physical adsorption and biodegradation.Therefore,it is necessary to explore a completely safe degradation technology.Semiconductor photocatalysis is a green,low-energy and strong oxidative degradation technology that can effectively degrade azo dyes into non-toxic small molecules and protect water resources.Fe₂O₃ is a semiconductor material with a narrow band gap width,which can respond to visible light in the range of46%of sunlight.However,due to its narrow band gap and dense structure,Fe₂O₃ has a high photoelectron-hole recombination rate and cannot efficiently perform photosynthetic reactions.According to a large number of studies,the formation of ferric oxide composite materials can effectively solve the above problems.In this paper,the petals of three different types?cherry blossom,hydrangea and rose?in the subfamily rosaceae were used as templates.By controlling the impregnation concentration and calcining temperature,the carbon/iron trioxide composites with biochip structure duplicating the surface morphology of petals were successfully prepared.The purpose is to increase the contact area of semiconductors with light and organic contaminants by using the precise structure of the biological template,and the biostructural carbon can provide photogenerated electron transfer and storage space for the material,and reduce the electron hole recombination rate.In the process of preparing the sample,it was found that different impregnation concentrations and calcination temperatures required for the preparation of the best performance of the different templates were different,which was related to the surface morphology of the template and the confinement effect of the thickness of the template.Before calcination,the thickness of the three petals was the largest in the rose,followed by the hydrangea,and the cherry was the thinnest.The optimum immersion concentrations were 0.10 mol/L,0.05 mol/L and 0.15 mol/L,respectively.According to scanning electron microscopy?SEM?and nitrogen adsorption-desorption?BET?analysis,it is known that hydrangea can be used as a template to prepare better samples with lower impregnation concentration,it also keeps the original form of the template from agglomerating and gives a larger specific surface area.The ferric oxide composite material was prepared by two calcination methods.The materials obtained by two methods were characterized by X-ray diffractometry?XRD?,high resolution transmission electron microscopy?HRTEM?,X-ray photoelectron spectroscopy?XPS?and UV-vis DRS.The results show that the material obtained by the step calcination method is a composite of?-Fe₂O₃ and?-Fe₂O₃ mixed phases.Moreover,the oxygen vacancy concentration in the material is significantly increased,the carbon content is also large,and the forbidden band width is remarkably lowered.Therefore,the obtained material can exhibit higher photocatalytic efficiency and activity.The photocatalytic degradation test showed that the degradation rates of the products obtained by one-step calcination of the three templates to the amino black solution with a concentration of 10 mg/L were 42%,57%,and 48%,respectively.The degradation rates of the samples obtained by the step-by-step calcination method were 47%,75%,and 61%,respectively,and the test results were consistent with the characterization results.The reason for this difference is that the sample obtained by the step calcination method has stronger magnetic properties because the material is doped with?-Fe₂O₃.By analyzing the ratio of?-Fe₂O₃ and?-Fe₂O₃,it is found that the photocatalytic performance and magnetic properties are higher when the content of the components is relatively uniform.