Preparation And Modification Of Porous Tubular G-C₃N₄ And Its Photocatalytic Properties For The Degradation Of Rhodamine B

At present,photocatalysis technology has attracted much attention as an effective method for the treatment of organic pollutants.The development of more efficient photocatalysts is the main strategy to promote the improvement of photocatalysis technology.Graphite-phase carbon nitride?g-C₃N₄?has attracted much attention due to its stable properties,low cost,non-toxic and visible light response,however,its application is limited by its small specific surface area,low quantum yield and narrow response range of visible light.Therefore,it is of great significance to improve its photocatalytic performance by modifying it to overcome the downsides.In this paper,the g-C₃N₄ photocatalyst with better removal efficiency of Rhodamine B?Rh B?has been modified by morphology control,metal doping and co-catalyst loading.The porous tubular g-C₃N₄ and its composite photocatalyst are prepared,and the performance and mechanism of its removal of Rh B have been discussed.First,the g-C₃N₄ material is prepared by one-step high temperature solid-state method with different precursor under different calcination atmosphere.The mixture of melamine and urea is roasted in Ar atmosphere.During the heating process,the urea is converted into cyanuric acid and combined with melamine to form a one-dimensional rod-like intermediate.The porous tube-like g-C₃N₄?CN?is prepared by heating the intermediate to release NH3,CO2 and other gases.This structure is helpful to provide more active sites,so that CN shows better performance than the samples prepared by single precursor.Second,in order to further adjust the morphology and bandgap width,Bi?NO3?3·5H2O is introduced as bismuth source to prepare bismuth doped g-C₃N₄.It is suggested that the source is doped into g-C₃N₄ in the form of Bi3+ ions and induces an amorphous transition.The sample?0.1BCN?with 0.1 g bismuth source has enhanced porous tubular structure and red shift has been observed in the absorption spectra.Under the same experimental conditions,0.1BCN photocatalyst has the highest photocatalytic activity.The rate constant of degradation of Rh B is 26.8 times of that of g-C₃N₄ prepared by melamine alone,and when the p H value of the reaction solution is 3.02,Rh B could be completely removed within 20 minutes under visible light irradiation.Finally,in order to promote the separation and transfer of photocarriers,the composite is constructed based on 0.1BCN.?1?Bi OCl/g-C₃N₄ composite is prepared by treating 0.1 BCN with hydrochloric acid.After 50 min of visible light irradiation,97.9 % Rh B could be removed by the photocatalyst.It is proved that 0.1BCN is suitable for Rh B wastewater containing Cl-.?2?WO/BCN composites are prepared by introducing tungsten oxide?W18O49?with oxygen vacancy into bismuth-doped g-C₃N₄ by solvothermal method.Due to the negative charge of W18O49 and the local plasma resonance effect?LSPR?,the composite exhibits good adsorption and photocatalytic properties for Rh B.