Study On Preparation And Characteristics Of Azobenzene Materials Based On Photoisomeric Energy Storage

Azobenzene materials store and release solar energy through reversible photoisomerization reactions.Under specific light conditions,azobenzenes are converted from trans to cis isomers while storing energy in the chemical bond.Under the stimulation of light and heat,azobenzenes are reverted from the cis to the trans isomer while releasing the heat.In today’s increasingly serious energy problem,the photoisomeric energy storage method of azobenzenes had received wide attention.However,traditional azobenzene molecules have low energy density and poor thermal stability,which cannot meet the requirements of high energy and long-term energy storage.In this paper,on the photoisomeric energy storage mechanism of azobenzene,using a molecular design approach,azobenzene molecules were grafted onto rigid ctarbon nanotemplates of graphite carbon nitride,and azobenzene-graphite carbon nitride hybrid materials were prepared.The results showed that the azobenzene molecules have been closely aligned on the graphite carbon nitride template,and the azobenzene moleculars spacing has been shortened.An azobenzene energy storage materials with high graft density and good thermal stability has been produced.In this paper,azobenzene derivatives（AZO-1）were prepared by coupling aniline diazonium salt with 3,5-dimethoxyaniline.Then,the azobenzene derivatives were covalently grafted onto the graphite carbon nitride lamellae surface by three repeated diazo radical reactions,and the target product azobenzene-graphite carbon nitride hybrid materials（AZO-1-C₃N₄）were prepared.The physical properties and microscopic morphology of azobenzene derivatives,graphite carbon nitride and azobenzene-graphite carbon nitride hybrid materials were characterized by Fourier transform infrared absorption spectroscopy（FT-IR）,X-ray diffraction spectroscopy（XRD）,X-ray photoelectron spectroscopy（XPS）,and scanning electron microscopy（SEM）method.The results showed that the target product azobenzene-graphite carbon nitride hybrid materials were successfully synthesized.The thermal stability of the analyzed materials were determined by thermogravimetric（TG）method.The results showed that the grafted hybrid materials were already stronger than the ungrafted azobenzene derivatives with respect to thermal stability.And the hybrid materials were stable state within 550℃,which met the temperature condition for application in solar energy storage system The hybrid materials were grafted three times repeatedly to increase the grafting density,which were calculated to be 1:51.3 by XPS.Due to the high grafting density,azobenzene molecules were tightly arranged on the template and had high thermal storage properties.The UV-Vis absorption spectra showed that the hybrid materials store energy by photoisomerization reaction under UV irradiation at a wavelength of 365 nm,and that the hybrid materials exceed the azobenzene derivatives in energy storage.The photoisomerization properties of the hybrid materials were analyzed under different light intensities,and the results showed that the stronger the light intensity,the faster the rate of photoisomerization of the hybrid materials.Meanwhile,the hybrid materials had the best photoisomerization conditions in several experimental conditions in this paper,at a UV light intensity of 40 mW/cm².The above results provide certain theoretical and experimental basis for the application in the field of solar energy storage.