AZOBENZENE-GRAPHENE METAL COORDINATION SOLAR PHOTOTHERMAL ENERGY STORAGE MATERIAL AND PREPARATION THEREOF

Abstract

The present disclosure relates to an azobenzene-graphene metal coordination solar photothermal energy storage material based on metal coordination bonds and a preparation method thereof. The method comprises the following steps: preparing reduced graphene oxide; preparing an azobenzene-graphene material; and preparing an azobenzene-graphene metal coordination solar photothermal energy storage material: dispersing the prepared azobenzene-graphene material in DMF, dissolving a certain amount of metal compound in DMF, adding the DMF solution of the metal compound into the DMF solution of the azobenzene-graphene, taking out the precipitate, washing off metal ions which do not participate in coordination, and drying the obtained product to obtain the azobenzene-graphene metal coordination solar photothermal energy storage material. The present disclosure also relates to a method for improving the solar photothermal energy storage ability of a molecular solar energy fuel, comprising using an azobenzene-graphene metal coordination solar photothermal energy storage material.

Claims

1. An azobenzene-graphene metal coordination solar photothermal energy storage material represented by the following chemical formula: ##STR00007## ##STR00008## wherein M=Mg, Ni, Zn, Cu or Ca; and X=Fe or Al.

2. A method for preparing an azobenzene-graphene metal coordination solar photothermal energy storage material comprising the following steps: (1) preparing reduced graphene oxide: hydrothermally reacting an aqueous solution of graphene oxide (GO) prepared using Hummers method to obtain an aqueous solution of reduced graphene oxide (RGO); (2) preparing an azobenzene-graphene material: preparing a hydrochloric acid solution of 4′-aminoazobenzene-4-sulphonic acid and a hydrochloric acid solution of NaNO.sub.2 respectively, adding the hydrochloric acid solution of NaNO.sub.2 dropwise into the hydrochloric acid solution of 4′-aminoazobenzene-4-sulphonic acid at 0-5° C. to form a diazonium salt; adding the diazonium salt into the aqueous solution of the reduced graphene oxide obtained in step (1) to react for a period of time; and washing the obtained product with water, N,N-dimethylformamide (DMF) and ethanol until no characteristic absorption peak of azo appears in the UV absorption detection of the filtrate; and drying to obtain an azobenzene-graphene material; and (3) preparing an azobenzene-graphene metal coordination solar photothermal energy storage material: dispersing the azobenzene-graphene material prepared in step (2) in DMF and dissolving a certain amount of a metal compound in DMF, adding the DMF solution of the metal compound into the DMF solution of the azobenzene-graphene, taking out the precipitate, washing off metal ions which do not participate in coordination, and drying the obtained product to obtain an azobenzene-graphene metal coordination solar photothermal energy storage material.

3. The method according to claim 2, wherein in step (1), the aqueous solution of graphene oxide (GO) is hydrothermally reacted at 60° C.-160° C. for 2-48 h.

4. The method according to claim 2, wherein in step (2), a coordinating group on the phenyl ring or pyridyl ring opposite to the amino group in the azo compound is a sulphonic acid group, a phosphoric acid group, carboxyl, hydroxyl, amino, nitro, a carbonic acid group, an ester group or an amide group.

5. The method according to claim 2, wherein in step (3), the metal compound used for coordination is MgCl.sub.2, NiCl.sub.2, ZnCl.sub.2, CuCl.sub.2, CaCl.sub.2), FeCl.sub.3, or AlCl.sub.3; that is, the coordination central ion in the azobenzene-graphene metal coordination solar photothermal energy storage material is a magnesium ion, a nickel ion, a zinc ion, a copper ion, a calcium ion, an iron ion, or an aluminum ion.

6. The method according to claim 2, wherein in step (3), the molar ratio of the metal compound used for coordination to azobenzene-graphene is (0.1-20):1.

7. A method for improving the solar photothermal energy storage ability of a molecular solar energy fuel, comprising using an azobenzene-graphene metal coordination solar photothermal energy storage material according to claim 1.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0022] FIG. 1 is a scanning electron microscope (SEM) image of the azobenzene-graphene material of the present disclosure.

[0023] FIG. 2 is a scanning electron microscope (SEM) image of the azobenzene-graphene metal coordination solar photothermal energy storage material of the present disclosure.

[0024] FIG. 3 is a transmission electron microscope (TEM) image of the azobenzene-graphene material of the present disclosure.

[0025] FIG. 4 is a transmission electron microscope (TEM) image of the azobenzene-graphene metal coordination solar photothermal energy storage material of the present disclosure.

[0026] FIG. 5 is the FT-IR spectra of the sulphonic acid azobenzene-graphene magnesium metal coordination solar photothermal energy storage material of the present disclosure.

[0027] FIG. 6 is the UV-Vis absorption spectra of the sulphonic acid azobenzene-graphene magnesium metal coordination solar photothermal energy storage material dispersed in DMF, showing the comparison of isomerization degree before UV-irradiated (0 min) and after UV-irradiated 30 min. It can be seen from the figure that the trans-enriched state is transformed into the cis-enriched state after ultraviolet irradiation, and solar energy is stored.

[0028] FIG. 7 is a differential scanning calorimetry analysis (DSC) exotherm diagram of the sulphonic acid azobenzene-graphene magnesium metal coordination solar photothermal energy storage material of the present disclosure.

[0029] FIG. 8 is a DSC exotherm diagram of the sulphonic acid azobenzene-graphene iron metal coordination solar photothermal energy storage material of the present disclosure.

DETAILED DESCRIPTION

[0030] The following description is given to further explain the present disclosure, rather than limit the scope thereof.

[0031] The method for preparing the azobenzene-graphene metal coordination solar photothermal energy storage material will be described in detail based on its particular structure, comprising: [0032] (1) preparing a reduced graphene oxide: adjusting the concentration of the aqueous solution of the graphene oxide (GO) prepared by Hummers method to 0.01-10 mg/mL, and hydrothermally reacting the aqueous solution at 60° C.-160° C. for 2-48 hours to obtain an aqueous solution of reduced oxidation graphene (RGO); [0033] (2) preparing an azobenzene-graphene material: dissolving aminoazobenzene with coordinating groups and NaNO.sub.2 into 1 mol/L HCl aqueous solution at room temperature, respectively, adding the hydrochloric acid solution of NaNO.sub.2 dropwise into the hydrochloric acid solution of 4′-aminoazobenzene-4-sulphonic acid at 0-5° C. to form a diazonium salt; adding the diazonium salt into the aqueous solution of the reduced graphene oxide obtained in step (1) to react for 2-24 h; washing the obtained product with water, N,N-dimethylformamide (DMF) and ethanol until no characteristic absorption peak of azo appears in the UV absorption detection of the filtrate; and then drying the obtained product in an oven at 60° C., to obtain the azobenzene-graphene material; [0034] (3) preparing an azobenzene-graphene metal coordination solar photothermal energy storage material: dispersing a certain amount of azobenzene-graphene material in DMF ultrasonically, and dissolving a metal compound in DMF ultrasonically with the molar ratio of the metal compound used for coordination to azobenzene-graphene being (0.1-20):1, and then adding the DMF solution of the metal compound into the DMF solution of the azobenzene-graphene and standing for 4-24 h, taking out the precipitate, washing off the meal ions which do not participate in coordination using ethanol, and drying the obtained product in an oven at 60° C. to obtain the azobenzene-graphene metal coordination solar photothermal energy storage material.

Example 1

[0035] (1) Preparing a reduced graphene oxide: The concentration of the aqueous solution of the graphene oxide (GO) prepared by Hummers method was adjusted to 1 mg/mL, and a hydrothermal reaction was performed at 80° C. for 12 h, to obtain an aqueous solution of the reduced graphene oxide (RGO).

[0036] (2) Preparing a sulphonic acid azobenzene-graphene material: 1.109 g of 4′-aminoazobenzene-4-sulphonic acid and 0.304 g of NaNO.sub.2 were dissolved into 20 mL of 1 mol/L HCl aqueous solution at room temperature, respectively. The hydrochloric acid solution of NaNO.sub.2 was added dropwise into the hydrochloric acid solution of 4′-aminoazobenzene-4-sulphonic acid at 0-5° C., to form a diazonium salt. The diazonium salt was added into 100 mL of 1 mg/mL the reduced graphene oxide solution obtained in step (1) to react for 24 h. The obtained product was washed with water, N,N-dimethylformamide (DMF) and ethanol until no characteristic absorption peak of azo appears in the UV absorption detection of the filtrate. Then the obtained product was dried in an oven at 60° C. to obtain the sulphonic acid azobenzene-graphene material.

[0037] (3) Preparing a sulphonic acid azobenzene-graphene magnesium (Mg) metal coordination solar photothermal energy storage material: 2.08 g of the sulphonic acid azobenzene-graphene material was dispersed in DMF ultrasonically. 3.81 g of MgCl.sub.2 was dissolved in DMF ultrasonically. Then the DMF solution of MgCl.sub.2 was added into the DMF solution of the sulphonic acid azobenzene-graphene and the mixture was stood for 12 h. The precipitate was taken out, and the meal ions which did not participate in coordination were washed using ethanol. The obtained product was dried in an oven at 60° C. to obtain the sulphonic acid azobenzene-graphene magnesium metal coordination solar photothermal energy storage material.

[0038] The obtained sulphonic acid azobenzene-graphene magnesium metal coordination solar photothermal energy storage material was represented by the following structural formula:

##STR00004##

Example 2

[0039] (1) Preparing a reduced graphene oxide: The concentration of the aqueous solution of the graphene oxide (GO) prepared by Hummers method was adjusted to 1 mg/mL, and a hydrothermal reaction was performed at 80° C. for 12 h, to obtain an aqueous solution of the reduced graphene oxide (RGO).

[0040] (2) Preparing a sulphonic acid azobenzene-graphene material: 1.109 g of 4′-aminoazobenzene-4-sulphonic acid and 0.304 g of NaNO.sub.2 were dissolved into 20 mL of 1 mol/L HCl aqueous solution at room temperature, respectively. The hydrochloric acid solution of NaNO.sub.2 was added dropwise into the hydrochloric acid solution of 4′-aminoazobenzene-4-sulphonic acid at 0-5° C., to form a diazonium salt. The diazonium salt was added into 100 mL of 1 mg/mL the reduced graphene oxide solution obtained in step (1) to react for 24 h. The obtained product was washed with water, N,N-dimethylformamide (DMF) and ethanol until no characteristic absorption peak of azo appears in the UV absorption detection of the filtrate. Then the obtained product was dried in an oven at 60° C. to obtain the sulphonic acid azobenzene-graphene material.

[0041] (3) Preparing a sulphonic acid azobenzene-graphene iron (Fe) metal coordination solar photothermal energy storage material: 2.08 g of sulphonic acid azobenzene-graphene material was dispersed in DMF ultrasonically. 6.48 g of FeCl.sub.3 was dissolved in DMF ultrasonically. Then the DMF solution of FeCl.sub.3 was added into the DMF solution of the sulphonic acid azobenzene-graphene material and the mixture was stood for 12 h. The precipitate was taken out, and the meal ions which did not participate in coordination were washed using ethanol. The obtained product was dried in an oven at 60° C. to obtain the sulphonic acid azobenzene-graphene iron metal coordination solar photothermal energy storage material.

[0042] The obtained sulphonic acid azobenzene-graphene iron metal coordination solar photothermal energy storage material was represented by the following structural formula:

##STR00005##

Example 3

[0043] (1) Preparing a reduced graphene oxide: The concentration of the aqueous solution of the graphene oxide (GO) prepared by Hummers method was adjusted to 1 mg/mL, and a hydrothermal reaction was performed at 80° C. for 12 h, to obtain an aqueous solution of the reduced graphene oxide (RGO).

[0044] (2) Preparing a sulphonic acid azobenzene-graphene material: 1.109 g of 4′-aminoazobenzene-4-sulphonic acid and 0.304 g of NaNO.sub.2 were dissolved into 20 mL of 1 mol/L HCl aqueous solution at room temperature, respectively. The hydrochloric acid solution of NaNO.sub.2 was added dropwise into the hydrochloric acid solution of 4′-aminoazobenzene-4-sulphonic acid at 0-5° C., to form a diazonium salt. The diazonium salt was added into 100 mL of 1 mg/mL the reduced graphene oxide solution obtained in step (1) to react for 24 h. The obtained product was washed with water, N,N-dimethylformamide (DMF) and ethanol until no characteristic absorption peak of azo appears in the UV absorption detection of the filtrate. Then the obtained product was dried in an oven at 60° C. to obtain the sulphonic acid azobenzene-graphene material.

[0045] (3) Preparing a sulphonic acid azobenzene-graphene nickel (Ni) metal coordination solar photothermal energy storage material: 2.08 g of sulphonic acid azobenzene-graphene material was dispersed in DMF ultrasonically. 5.18 g of NiCl.sub.2 was dissolved in DMF ultrasonically. Then the DMF solution of NiCl.sub.2 was added into the DMF solution of the sulphonic acid azobenzene-graphene material and the mixture was stood for 12 h. The precipitate was taken out, and the meal ions which did not participate in coordination were washed using ethanol. The obtained product was dried in an oven at 60° C. to obtain the sulphonic acid azobenzene-graphene nickel metal coordination solar photothermal energy storage material.

[0046] The obtained sulphonic acid azobenzene-graphene nickel metal coordination solar photothermal energy storage material was represented by the following structural formula:

##STR00006##

[0047] As can be seen from FIGS. 1 and 2, the morphology of the azobenzene-graphene metal coordination solar photothermal energy storage material aggregates after coordinated with metal. This is because the azobenzene-graphene is connected together by the metal coordination bonds. As also can be seen from FIGS. 3 and 4, the morphology of the azobenzene-graphene metal coordination solar photothermal energy storage material aggregates after coordinated with metal, and it is preliminarily proved that the azobenzene-graphene metal coordination solar photothermal energy storage material is obtained. After the FT-IR spectra test was performed, as shown in FIG. 5, the absorption peak of the metal coordination bond appears in the FT-IR spectra of the sulphonic acid azobenzene-graphene magnesium metal coordination solar photothermal energy storage material, which once again proves that the azobenzene-graphene metal coordination solar photothermal energy storage material is obtained. FIG. 6 shows the UV-Vis absorption spectra of sulphonic acid azobenzene-graphene magnesium metal coordination solar photothermal energy storage material. The isomerization occurs before UV-irradiated (0 min) and after UV-irradiated 30 min. It can be seen from the figure that the trans-enriched state is transformed into the cis-enriched state after ultraviolet irradiation, and solar energy is stored. FIG. 7 shows that the sulphonic acid azobenzene-graphene magnesium metal coordination solar photothermal energy storage material has a heat storage density of up to 719.2 J/g. FIG. 8 shows that the sulphonic acid azobenzene-graphene iron metal coordination solar photothermal energy storage material has a heat storage density of up to 592.4 J/g. The azobenzene-graphene metal coordination solar photothermal energy storage material exhibits excellent heat storage performance.

[0048] Adjusting the functional groups, coordination metals, process parameters and so on according to the present disclosure can all realize the preparation of an azobenzene-graphene metal coordination solar photothermal energy storage material, which exhibits a performance basically consistent with the present invention in the test. That is, through the DSC test, the obtained azobenzene-graphene metal coordination solar photothermal energy storage material has a heat storage density of 400-750 J/g. The present invention has been exemplarily described above.

[0049] The azobenzene-graphene metal coordination solar photothermal energy storage material obtained in the present disclosure has an excellent heat storage density and a long heat storage time, and can be applied in the field of solar photothermal energy storage.

[0050] An azobenzene-graphene metal coordination solar photothermal energy storage material and a preparation method thereof are disclosed and provided in the present disclosure. Those skilled in the art can achieve it by learning from the content of this context and appropriately changing the conditions or routes and the like. Although the method and preparation technology of the present disclosure have been described through preferred embodiments, those skilled in the art can obviously modifying and recombining the methods and technical routes described herein without departing from the content, spirit and scope of the present disclosure to achieve the final preparation technique.