Study On Modification Of Carbon Nitride-based Photocatalyst

Graphite carbon nitride（g-C₃N₄）is a non-metallic photocatalyst with great application prospects.However,there are many shortcomings.The common improvement methods are generally divided into two methods:element doping and morphology control.In this work,morphology control is taken as the main modification method giving consideration to the method and idea of element doping.To consider about environmental protection,preparation speed,cost,modification effect and other issues,a series of effective modifications are taken for g-C₃N₄.Herein,the specific work of three photocatalysts with excellent characterization results and practical application effects are showed as follow:First,a boron-doped carbon nitride with nanotube structure was prepared to photocatalytically degrade the rhodamine B solution.Using a hydrothermal method,melamine was pretreated by boric acid as a precursor,and then calcined at a high temperature to prepare boron-doped carbon nitride nanotubes.The results show that the modified catalyst has more active sites and better electronic structure,and its catalytic performance is greatly improved.Second,two bubble template agents was used to prepare porous carbon nitride nanosheets,which was adopted to study the photocatalytic degradation of organic pollutants.Compared with using a single bubble template,the porous carbon nitride nanosheets prepared by using two bubble templates at the same time require fewer raw materials to achieve the same indicators,and the preparation process is simple and the performance is better.Third,a porous boron-doped carbon nitride with a fluffy structure was prepared using boric acid and ammonium chloride as raw materials.The characterization results show that its BET specific surface area is greatly increased,and it has a rich pore structure.At the same time,the separation efficiency of photogenerated carriers is excellent,the band gap is moderate,and the catalytic performance has been greatly improved.And through the study of the reaction mechanism,it is determined that the main active substance of the modified catalyst is superoxide radical.