Preparation And Photocatalytic Properties Of Graphite Phase Carbon Nitide As Dfficiency Photocatalyst

With the passage of time,energy and environmental problems have become increasingly serious,restricting human production and life.In order to solve the above problems,everyone expressed their opinions.Among many renewable energy projects,semiconductor-based photocatalytic technology has attracted wide attention due to its diverse applications in energy and environment.As a new,green and feasible technology,photocatalytic technology can use solar energy to decompose water to generate hydrogen and oxygen,degrade organic pollutants,sterilize and disinfect without secondary pollution,and become one of the most potential solution to solve energy and environmental problems.At first,traditional catalyst was represented by titanium dioxide,but its application in production and life was still limited due to its low solar energy utilization,large band gap energy,small specific surface area and easy combination of photogenerated electrons and holes in traditional TiO₂ and other semiconductor photocatalysts.Therefore,in the process of seeking semiconductor catalysts with high activity and response to visible light,carbon nitride?g-C₃N₄?of graphite phase,due to its unique characteristics and abundant earth resources,has aroused a strong response in the research field as the next generation of photocatalyst.In addition,in environmental problems,the pollution of formaldehyde is becoming increasingly serious,so it is particularly important to prepare a catalyst that has a significant degradation effect on formaldehyde.So in this paper,a new type of semiconductor photocatalyst g-C₃N₄as the research object,according to its own shortcomings,and design a series of experiments based on the characteristics of material itself to increase the specific surface area of materials,finally we will use a simple way to synthesis of Ag/g-C₃N₄composite photocatalyst,makeing the synthesized sample not only have the surface plasmon resonance effect of silver,but also has a large specific surface area and strong photocatalytic activity.The specific contents of this paper are as follows:1.Synthesis of g-C₃N₄ with high activity and practical application of photocatalytic degradation of formaldehydeOrganic acid and organic aldehyde were used to treat melamine,and porous g-C₃N₄ nanosheets with large specific surface area were prepared under hydrothermal conditions.The obtained highly active powder is used to degrade formaldehyde in a closed air chamber.Compare the samples treated with different organic acids and organic aldehydes to the different degradation effects of formaldehyde and find the best sample.XRD,nitrogen adsorption-desorption,SEM,TEM,and UV-vis were used to analyze the specific surface area and pore size distribution of the sample,as well as the sample formation process,structure,morphology,and optical properties.The study found that the specific surface area of the treated samples was significantly increased and had a special morphology.This is beneficial for g-C₃N₄ nanosheets to better react with pollutants,consume more pollutants,and also facilitate the rapid movement of electrons and holes on the surface of the material.Finally,we used visible light to irradiate a closed air chamber,which contained formaldehyde gas at a concentration of about 0.45mg/cm³.The photocatalytic activity of the samples was analyzed by the change in formaldehyde concentration in the glass chamber to compare organic aldehydes and organic acids Which sample works better.The results show that the sample treated with glyoxal can degrade formaldehyde to 50%,followed by the sample treated with citric acid.This is mainly because the porous structure of the sample adds more reactive sites,which greatly improves the photocatalytic activity of the catalyst.2.Adopt a new method to synthesize Ag/g-C₃N₄ composite film,enhance the plasmon resonance effect,and then improve the photocatalytic activityThe Ag/g-C₃N₄ composite film was prepared on the conductive glass by the combination of electrodeposition and photodeposition,so that the synthesized sample not only has the surface plasmon resonance effect of silver,but also has a large specific surface area and strong photocatalytic activity.The effects of different silver loading and deposition time on the structure,optical properties and photocurrent of the composite films were systematically studied.Various properties of the samples were characterized by different characterization methods,and the formation mechanism of the samples was explored.The Ag/g-C₃N₄ composite film obtained with an electrodeposition time of 5min,a silver loading of 0.01g,and a photodeposition time of 10min has the best optical properties.The photocurrent reaches 5 microamperes,and the larger photocurrent results in photogeneration.The separation of carriers and holes is more efficient.The photocatalytic activity of the sample was tested by visible light irradiation with isopropanol.The results show that the Ag/g-C₃N₄ composite film can enhance the photocatalytic activity by enhancing the surface plasmon resonance effect,so that the activity of the composite film is 3times that of pure g-C₃N₄ film.