Abstract:

In order to solve the environmental pollution caused by organic dyes and automobile exhaust NO _x，C₃N₅/NH₂-MIL-125（Ti） composite photocatalytic materials were prepared by solvothermal method.The crystal morphology，elemental composition，spectral absorption，photoelectron-hole recombination and charge transfer resistance of the composites were characterized by X-ray diffraction（XRD），scanning electron microscopy（SEM），transmission electron microscopy（TEM），X-ray photoelectron spectroscopy（XPS），ultraviolet-visible diffuse reflectance spectroscopy（UV-vis DRS），steady-state fluorescence spectroscopy（PL） and electrochemical impedance spectroscopy（EIS）.It was applied to the photocatalytic degradation of dye rhodamine B（RhB）.The concrete mortar was modified by C₃N₅/NH₂-MIL-125（Ti），which was applied to the photocatalytic degradation of automobile exhaust NO _x .The results showed that the XPS characterization proved the successful construction of the heterojunction between C₃N₅ and NH₂-MIL-125（Ti），realized the efficient separation of photoelectron-holes，broadened the spectral absorption range，and significantly reduced the charge transfer resistance，showing good photocatalytic activity，which was obviously better than that of single C₃N₅ and NH₂-MIL-125（Ti）.The degradation rate of RhB reached 98.5% within 60 min under visible light irradiation，and it still showed good photocatalytic activity after 5 cycles.A small amount of doping of C₃N₅/NH₂-MIL-125（Ti） made ordinary concrete mortar exhibited NO _x degradation activity and was beneficial to the improvement of compressive strength of mortar concrete.

Key words: C₃N₅, NH₂-MIL-125（Ti）, concrete mortar, photocatalysis, NO _x degradation, rhodamine B, hydration performance