Preparation Of Oxygen-Doped Carbon Nitride/Red Phosphorus Composite Photocatalysts And Its Performance Exploration

Semiconductor photocatalytic technology has good prospects in controlling water pollution and developing green new energy.Recently,non-metallic photocatalytic materials such as red phosphorus?P?and carbon nitride?CN?have attracted much attention due to their wide sources,simple preparation and high catalytic activity.However,the rapid recombination of photogenerated carriers?electrons and holes?reduces the photocatalytic efficiency and greatly limits the wide application of photocatalytic technology.Therefore,it is of great significance for the development of red phosphorus and carbon nitride photocatalysts,using an effective strategy of modification to improve the separation and migration of electrons and holes and thus enhance their photocatalytic activity.This paper focuses on two aspects:Firstly,oxygen-modified carbon monoxide?OCN?photocatalysts were prepared by a simple calcination method using melamine as raw material,and OCN/P composite photocatalysts with different composition ratios were prepared by mechanical miling.The structure,morphology,elemental composition and optical characteristics of the composite photocatalyst were characterized by X-ray diffraction?XRD?,scanning electron microscopy?SEM?and X-ray photoelectron spectroscopy?XPS?.The energy level structure information of the synthesized catalyst was obtained by electrochemical means.The activity of the photocatalysts were evaluated by degrading malachite green?MG?under visible light irradiation.The results show that the degradation rate of composite photocatalyst 20%OCN/P is up to 99%in 20 min.The degradation rate constant of MG(0.12 min^-1)is about 4 times than that of commercial red phosphorus.The heterojunction of OCN and P inhibits the recombination of electron-hole pairs and improves the photocatalytic performance.Secondly,different proportion of composite samples of Ni?OH?₂/P-Pt/OCN were prepared using Ni?OH?₂ and Pt as dual assistants.The phase,constitute,structure and optical characteristic of the composite photocatalysts were analyzed using different characterization methods.The photocatalytic hydrogen production performance of the catalysts was evaluated under visible light???29?400 nm?.The experimental results of photocatalytic hydrogen production showed that the composite sample Ni?OH?₂/P-Pt/OCN exhibited higher activity than Pt/OCN and Ni?OH?₂/P.The sample with mass ratio of Ni?OH?₂/P to Pt/OCN of 1:5,the total amount of hydrogen produced in 4 h is12?mol.In short,novel metal-free photocatalysts were prepared by different methods and their physicochemical properties and photocatalytic performance were characterized and evaluated.The recombination of electron-hole pairs was inhibited and thus the activity of the catalysts was much improved by the modification,which is meaningful for the application the metal-free photocatalysts.