Research On Preparation And Catalytic Performance Of G-C₃N₄ Based Nanocomposites

In this thesis,a modified H-g-C₃N₄ nanomaterial with good performance was prepared based on the reaction method of thermal modification of hydrogen peroxide.Moreover,its catalytic performance was studied and discussed in depth.A series of H-g-C₃N₄-based nanocomposites were prepared by simple water-phase reaction methods.The photocatalytic properties of the nanocomposites were tested,and the possible reaction mechanism was analyzed based on experimental phenomena and electrochemical test results.The details are as follows:(1)H-g-C₃N₄ was prepared by thermal modification of hydrogen peroxide.The influence of reaction time,hydrogen peroxide concentration and reaction temperature on the material were discussed through various characterization methods.Under visible light irradiation,H-g-C₃N₄ material can degrade Rh B(50mg·L^-1)to 97.4%in 60min,and the degradation rate constant is 0.056 min^-1.It is 1.6 times the degradation rate(K=0.035)of the original g-C₃N₄ nanomaterial.(2)A series of H-g-C₃N₄/CdS binary nanocomposites were prepared based on the electrostatic self-assembly method in the water phase.It was characterized and analyzed by XRD,SEM,UV-Vis,FT-IR,PL,etc.,and proved the successful combination of the two.Under visible light irradiation,the binary nanocomposite has a degradation rate of 98.6%for Rh B(50mg·L^-1)in 25 min,and its degradation rate constant is 0.145min^-1.The degradation rate of tetracycline hydrochloride(20mg·L^-1)at 120min is 70.6%,and the degradation rate constant is 0.010min^-1.(3)The H-g-C₃N₄/Au nanocomposite was prepared by the reduction method based on the aqueous phase.It was characterized and analyzed by XRD,SEM,UV-Vis,FT-IR,PL,etc.,and proved the successful combination of the two.Under visible light irradiation,the hydrogen production of H-g-C₃N₄/Au nanocomposite at 3 hours is 2.4 mmol·g^-1,and the hydrogen production rate is 0.8 mmol·g^-1·h^-1.After 4 cycles of 12h cycle hydrogen production experiment,the hydrogen production of the material is 95.0%of the first cycle.(4)The H-g-C₃N₄/Au/CdS nanocomposite material was prepared based on the semiconductor/noble metal/semiconductor's theoretical design.It has been characterized and analyzed by XRD,SEM,UV-Vis,FT-IR,PL,etc.,and proved the successful combination of the three.Under visible light irradiation,the hydrogen production of H-g-C₃N₄/Au/CdS nanocomposite at 3 hours is 6.72mmol·g^-1,and the hydrogen production rate is 2.27mmol·g^-1·h^-1;After 4 cycles totalling 12h of hydrogen production experiment,the hydrogen production of the material was 98.2%of the first cycle.(5)The H-g-C₃N₄/Au/Ag nanocomposite was prepared by the one-step reduction method based on the aqueous phase.It was characterized and analyzed by XRD,SEM,UV-Vis,FT-IR,PL,etc.,which proved that the bimetallic material was successfully prepared.Furthermore,the concentration limit of the one-step reduction method was determined.Under visible light irradiation,the hydrogen production of H-g-C₃N₄/Au/Ag nanocomposite at 3 hours is 11.55 mmol·g^-1,and the hydrogen production rate is 3.85mmol·g^-1·h^-1;After 4 cycles of 12h cycle hydrogen production experiment,the hydrogen production of the material was 92.5%of the first cycle.