| Photocatalytic technology,which can convert abundant solar energy into clean and environmentally friend hydrogen,is believed to be an ideal way to solve the energy and environment issues.As a star material in the field of photocatalysis,graphite phase carbon nitride has been studied a lot of doping and modification.However,in terms of preparation,the muffle furnace high temperature thermal polymerization method is used,and there are relatively few breakthrough studies.In this paper,in view of the fast and efficient microwave heating,a series of g-C3N4based composite photocatalysts were prepared by microwave-assisted heating,and the performance of photocatalytic hydrogen production was improved.The main results are as follows:1.In-situ synthesis of AgNbO3/g-C3N4 photocatalyst via microwave heating method for efficiently photocatalytic H2 generation.AgNbO3/g-C3N4 sample showed enhanced performance in photocatalytic H2-generation under visible light illumination.The H2-evolution rate is determined to be 88?mol·g-1·h-1,which reaches2.0 times of g-C3N4.XRD,XPS,FT-IR,SEM,TEM,experiments were performed to confirm the binary structure of the synthesized AgNbO3/g-C3N4 composite.N2-adsorption and visible diffuse reflection spectroscopy?DRS?analyses indicated that the addition of AgNbO3 to g-C3N4 showed nearly negligible influence on the specific surface area and the optical property.Photoluminescence?PL?spectroscopy experiment suggested that the AgNbO3/g-C3N4 displayed reduced PL emission and longer lifetime of photoexcited charge carriers than g-C3N4,which could be ascribed to the suitable band potential and the intimate contact of g-C3N4 and AgNbO3.This result was also confirmed by the transient photocurrent response experiment.The influence of the enhanced charge separation was displayed in their photocatalytic reaction;2.Microwave heating assisted synthesis of novel SnSe/g-C3N4 composites for effective photocatalytic H2 production.The study found that SnSe microchips can spontaneously disperse into SnSe nanoparticles on the surface of g-C3N4 nanosheets during microwave heating.The formed SnSe/g-C3N4 heterojunction gives the catalyst higher carrier separation efficiency and higher efficiency Photocatalytic hydrogen production capacity.Under simulated sunlight,the best SnSe/g-C3N4 sample displayed a H2-production velocity of 1064?mol·g-1·h-1,which is 1.8 folds faster than that of neat g-C3N4.;3.Using melamine,boric acid,and urea as raw materials,B-doped g-C3N4?B-g-C3N4?was efficiently synthesized by microwave heating for 40min.The optimal B-g-C3N4 exhibited a H2 production rate of 1439 and 400?mol·g-1·h-1 under simulated sunlight and visible light irradiation,respectively.This values are about 2.4 times higher than that of pure g-C3N4.;4.P-doped g-C3N4 was synthesized by microwave-assisted heating method,and Ag3PO4 nanoparticles were formed on the surface of P-g-C3N4 by ion exchange method.An Ag3PO4/P-g-C3N4composite catalyst was constructed.The doping of P improves the bulk carrier separation efficiency of g-C3N4,and the introduction of Ag3PO4 nanoparticles further promotes the separation of photogenerated charges on the surface.Therefore,Ag3PO4/P-g-C3N4 composites show better photocatalytic hydrogen production performance than g-C3N4.The best Ag3PO4/P-g-C3N4 hybrid shows a photocatalytic H2 production rate of 1221 and 90.2?mol·g-1·h-11 under simulated sunlight and visible light,respectively.This value is 2.1 and 1.4 times greater than that of g-C3N4 and P-g-C3N4,respectively. |
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