Preparation Of Z-scheme G-C₃N₄ Composite Photocatalytic Material And Its Photocatalytic Performance

In recent years,there are more and more problems in resources consumption and environmental pollution,and it is a key to balance the resources saving and environmental protection.In the field of environmental protection,there are some drawbacks in the traditional pollutant treatment technologies,such as high cost,incomplete degradation of contaminant,secondary pollution and so on.On the basis of this,it is important to search for a clean and efficient treatment technology.As a clean,energy-saving and environmental-friendly technology,photocatalytic treatment technology has been paid highly attention among researchers since it was born.In the process of research and development,many semiconductors and oxides were gradually developed photocatalytic property.As a metal-free polymer,g-C₃N₄ had displayed tremendous potential in photocatalytic field due to its outstanding properties.In this paper,g-C₃N₄ was prepared with thermal polymerization method.Aiming at the low photoelectron-hole pair separation efficiency and small visible light response range,different semiconductor composite photocatalysts based on carbon nitride were constructed to improve their photocatalytic activity.Different characterized methods,including XRD?SEM?FT-IR?XPS?UV-vis?PL?EIS and photocurrent,were implemented to analyze the morphology,chemical components,electrochemical and other properties of the photocatalysts.The photocatalytic performance of the catalysts were tested by the degradation of TC solution under light irradiation.Moreover,trapping experiment was carried out to certify the main active species which played an important role in photocatalytic reaction.Based on above experimental and characterized results,the Z-scheme photocatalytic machenism was proposed.The main contents in this paper were as follow:1)nano-meter LaCoO₃ was prepared by a modified citric acid-assisted hydrothermal method,and then g-C₃N₄/LaCoO₃ composite was prepared by facile precipitation mixing method.The SEM pictures showed that g-C₃N₄ and LaCoO₃ were tightly combined together,and the photogenerated carriers were seperated efficiently due to the matched VB and CB of g-C₃N₄ and LaCoO₃.The photocatalytic experiment revealed that the great photodegradation activity in the presence of g-C₃N₄/LaCoO₃ heterojunction under the full spectrum,and the optimal degradation rate was up to 92%.2)BiVO₄ doped metal Cu was prepared by hydrothermal method,and then BiVO₄/Cu/g-C₃N₄ heterojunction was prepared by facile precipitation mixing method.The electrochemical experiments displayed the interface charge transfer between two semiconductors were improved with the doping of Cu.At the same time,it was proved that the photocatalytic performance of the heterojunction was obviously enhanced,the optimal degradation of TC was 74.8%.3)CdMoO₄ contained CNTs was prepared by hydrothermal method,and then CdMoO₄/CNTs/g-C₃N₄heterojunction was prepared by facile precipitation mixing method.The electrochemical characterization results showed that the seperation of photogenarated electron-hole pairs was improved and the recombination,simultaneously,between the electrons and holes were restrained efficiently.As it was shown in the UV-vis spectrum,the adsorption of visible light region was clearly red shifted.It was shown that the photocatalytic performance was improved obviously in the photodegradation TC experiment under the visible light.The photodegradation of TC was up to 85.3%with the optimal composite ratio under the visible light irradiation.Furthermore,the composite still hold a great activity after 5 time cycling.