阅读说明：本技术 一种氧化石墨烯上复合硫化锌的三维花束状结构纳米材料及应用及制备方法 (Three-dimensional flower bunch-shaped structure nano material compounded with zinc sulfide on graphene oxide, application and preparation method ) 是由 张瑶瑶 郭海峰 朱磊 陈舒晗 胡欣悦 降子帆 李博解 何边阳 李维双 汪连生 于 2021-07-26 设计创作，主要内容包括：本发明公布了一种氧化石墨烯上复合硫化锌的三维花束状结构纳米材料及应用及制备方法,其制备步骤主要包含以下四部分：(1)采用自由基聚合法制备出形貌可控的温敏材料聚N-异丙基丙烯酰胺和N,N-二甲基丙烯酰胺(PNxDy),并对其形貌进行表征；(2)氧化石墨烯的制备；(3)以PNxDy为模板,硫化锌复合氧化石墨烯材料的制备及形貌表征；(4)将形貌优良的材料进行电池组装和性能测试；(5)将形貌优良的材料进行光催化降解甲基橙性能测试。本发明得到的以PNxDy为模板,硫化锌复合氧化石墨烯材料不仅提高了ZnS作为电池材料的比容量,且材料循环性能稳定、耗损少,光催化性能优异。(The invention discloses a three-dimensional flower bunch-shaped structure nano material compounded with zinc sulfide on graphene oxide, and an application and a preparation method thereof, wherein the preparation method mainly comprises the following four steps: (1) preparing temperature-sensitive materials poly (N-isopropyl acrylamide) and N, N-dimethyl acrylamide (PNxDy) with controllable shapes by adopting a free radical polymerization method, and characterizing the shapes of the temperature-sensitive materials; (2) preparing graphene oxide; (3) preparing a zinc sulfide composite graphene oxide material and characterizing the appearance by taking PNxDy as a template; (4) carrying out battery assembly and performance test on the material with excellent appearance; (5) and (3) carrying out a performance test on the material with excellent appearance in the photocatalytic degradation of methyl orange. The PNxDy template-based zinc sulfide composite graphene oxide material obtained by the invention not only improves the specific capacity of ZnS as a battery material, but also has stable material cycle performance, less loss and excellent photocatalytic performance.)

1. The three-dimensional flower bunch-shaped structure nano material is characterized by comprising a three-dimensional flower bunch-shaped structure graphene oxide sphere, two-dimensional graphene oxide sheets positioned on the sphere and ZnS nano particles deposited on the surfaces of the two-dimensional graphene oxide sheets; the three-dimensional flower bunch-shaped structure nano material of the zinc sulfide compounded on the graphene oxide is prepared by adding the graphene oxide and Zn containing cations into an aqueous solution of a temperature-sensitive material PN80D4²⁺The soluble salt is evenly dispersed by ultrasonic, and then the soluble salt is added with S containing anions^2-Uniformly mixing the soluble salt, performing hydrothermal reaction on the mixed solution at the temperature of 120-160 ℃ to obtain a precipitate, and washing and centrifuging to remove the precipitate obtained from the temperature-sensitive material PN80D4, wherein the temperature-sensitive material PN80D4 is a temperature-sensitive material; graphene oxide, cation-containing Zn²⁺The soluble salt is mixed according to 100mg: 2-6 mmol, and the soluble salt contains cation Zn²⁺With a soluble salt of S containing an anion^2-The mixing ratio of the soluble salt of (1): 2;

the temperature-sensitive material PN80D4 is poly N-isopropyl acrylamide-co-N, N-dimethyl acrylamide, 80 represents the polymerization degree of the N-isopropyl acrylamide, and 4 represents the polymerization degree of the N, N-dimethyl acrylamide.

2. The graphene oxide-zinc sulfide composite three-dimensional flower-bunch-structured nanomaterial according to claim 1, wherein the diameter of the ZnS nanoparticle is 10-20 nm, the particle size of a graphene oxide sphere with a three-dimensional flower-bunch-structured structure is 4-6 μm, and the diameter of a two-dimensional graphene oxide sheet is 1-2.5 μm.

3. The application of the three-dimensional flower bunch-like structure nano material compounded with zinc sulfide on the graphene oxide according to any one of claims 1 to 2 in preparation of a lithium ion battery.

4. The use according to claim 3, wherein the lithium ion battery is prepared by the following steps: grinding and sieving a three-dimensional bouquet-shaped structure nano material compounded with zinc sulfide on graphene oxide, mixing the ground graphene oxide with Super-P-Li and polyvinylidene fluoride according to a mass ratio of 8:1:1, adding N-methyl pyrrolidone, stirring the mixture in a disc turbine stirrer to be viscous, pouring slurry on a current collector copper foil for coating, placing the current collector copper foil in a vacuum drying box for drying at 60 ℃ for 24 hours, slicing the dried product to prepare a lithium ion battery electrode, and finally assembling and sealing the lithium ion battery electrode in a glove box filled with argon to prepare a button type lithium ion battery, wherein the lithium ion battery measures a circulation curve under the conditions that the voltage range is 0.05-3V and the current density is 100mA/g, the battery circulation efficiency is not less than 90 volt-ampere, the specific capacity after 50 cycles is 802mAh/g, and charging and discharging specific capacity curves are overlapped.

5. The preparation method of the three-dimensional flower bunch-like structure nano material compounded with zinc sulfide on the graphene oxide according to any one of claims 1 to 2, characterized by comprising the following steps:

(1) preparing a temperature-sensitive material PNxDy by adopting a free radical polymerization method or a controllable fracture chain transfer polymerization method, wherein the temperature-sensitive material PNxDy is poly-N-isopropyl acrylamide-co-N, N-dimethyl acrylamide, x represents the polymerization degree of the N-isopropyl acrylamide, x is 80, y represents the polymerization degree of the N, N-dimethyl acrylamide, and y is 4;

(2) dissolving PN80D4 serving as a template in deionized water to obtain hydrogel, and adding a graphene oxide material and Zn containing cations²⁺Is subjected to ultrasonic dispersion, and then is added with S containing anions^2-The soluble salt is mixed evenly, wherein the graphene oxide and the salt contain cation Zn²⁺The soluble salt is mixed according to 100mg: 2-6 mmol, and the soluble salt contains cation Zn²⁺With a soluble salt of S containing an anion^2-The mixing ratio of the soluble salt of (1): 2;

(3) and carrying out hydrothermal reaction on the mixed solution at the temperature of 120-160 ℃ to obtain a precipitate, washing with deionized water, washing with absolute ethyl alcohol, centrifuging, repeating the above operation for several times, removing the temperature-sensitive material PN80D4, and finally drying to obtain the graphene oxide-zinc sulfide-composited three-dimensional flower-bunch-structure nano material.

6. The method according to claim 5, wherein in the step (1), during the preparation of the temperature-sensitive material PN80D4, AIBN is used as an initiator, N-isopropylacrylamide is used as a hydrophilic monomer, N, N-dimethylacrylamide is used as a hydrophobic monomer, mercaptoethylamine hydrochloride is used as a blocking agent, anhydrous methanol is used as a reaction solvent, and nitrogen is used as a protective gas.

7. The method according to claim 5, wherein in the preparation process of the temperature-sensitive material in the step (1), the reaction temperature is 60-80 ℃ and the reaction time is 12-24 h. After the reaction was complete, diethyl ether was used as a precipitant to afford a white solid. The vacuum drying temperature is 30-60 ℃, and the drying time is 8-16 h.

8. The method according to claim 5, wherein the graphene oxide in the step (2) is prepared by a Hummer method.

9. The method according to claim 5, wherein the hydrothermal reaction in the step (3) is carried out under the conditions of 120-140 ℃ and the reaction time of 8-12 h.

10. The use of the three-dimensional flower-bunch-structured nano-material of zinc sulfide composited on graphene oxide according to any one of claims 1 to 2 as a photocatalyst.

Technical Field

The invention relates to the field of composite material preparation, in particular to a preparation method of a zinc sulfide composite graphene oxide material by taking a temperature-sensitive polymer PNxDy as a template after the temperature-sensitive polymer PNxDy is added.

Background

A lithium ion battery is also called as a rocking chair battery, and the main components of the lithium ion battery are a positive electrode, a negative electrode, a diaphragm and electrolyte. The lithium ion secondary battery is a lithium ion concentration difference battery, when the battery is in a discharging state, lithium ions released by a positive electrode material containing much lithium enter an electrolyte, released electrons pass through an external circuit, and lithium ions dissociated in the electrolyte reach a negative electrode after passing through a diaphragm and are embedded into a layered negative electrode material for storage, so that a discharging process is completed; and the charging process is the other way round. In the process of charging and discharging, lithium ions are inserted into and taken out of the layered materials at two sides, the interplanar spacing of the materials can be generally only influenced, and the crystal lattice cannot be damaged. Lithium ions move back and forth between the positive and negative electrodes of the battery without being attenuated, which is why the lithium ion battery is called a "rocking chair type battery".

The energy density of lithium ion batteries depends to a large extent on the negative electrode material, which, in the case of new non-carbon negative electrode materials, zn-based materials always show better cycle performance, but the zinc reserves in China are rich, the material is highly regarded as a very promising cathode material, and researches on sulfide show that the existence of S can buffer the volume effect of metal Li in the alloying process and enhance the stability of the structure, for example, as shown in a ZnS/graphene material prepared by a hydrothermal method in figure 4, after 50 times of charge and discharge tests under the current density of 100mA/g, the lithium intercalation capacity still has 536mAh/g which is 89.3 percent of the first 600mAh/g, the capacity is attenuated by 11.7 percent, it can be seen that the ZnS/graphene anode material has excellent cycling stability, which is probably because S in the ZnS material is firstly decomposed into Zn and Li during the first discharge.₂Reacting S, Zn and lithium ions to obtain Li-Zn alloy, extracting lithium ions from Zn during charging, and regenerating ZnS, wherein Li is not circulated for the first time₂The S phase still participates in electrochemical reaction, repeated charge and discharge are mainly repeated deintercalation of lithium ions in Zn and regeneration of partial ZnS, and Li formed in the first discharge process₂S cannot be completely reversed in the subsequent charging and discharging processes.

For the negative electrode material of the lithium ion battery, the particle size of the material has important influence on the electrochemical performance of the negative electrode material, because the volume change of the negative electrode material with smaller particles is smaller than that of a large particle material in the electrochemical circulation process, and because more and smaller pores exist among the smaller particles, the whole electrode cannot be damaged even if the alloy particles have great volume change, the stability of the electrode structure is facilitated, and the circulation performance is improved. And the smaller the particle, the shorter the diffusion path of lithium ions therein. Therefore, in the development of graphene electrode materials, it is highly desirable for those skilled in the art to improve the cycling stability of composite materials by changing the microstructure of the materials.

But at the same time lithium metal batteries have problems: when lithium metal is used as a negative electrode material, due to fine fluctuation of the surface, uneven electrochemical deposition can be caused by the fluctuation in the whole charging and discharging process, larger lithium dendrites can be generated when a certain amount of lithium is accumulated, meanwhile, the surface of the crystals is more uneven, the specific capacity is attenuated due to the consumption of the lithium metal, more seriously, the dendrites are easy to break through a diaphragm, so that the positive electrode and the negative electrode of the battery are connected and are in short circuit, and the lithium metal battery is quite dangerous. Therefore, the search for suitable lithium intercalation cathode materials, lithium intercalation anode materials and corresponding electrolytes has become one of the main research directions in this field. The negative electrode of graphene belonging to an intercalation-deintercalation type is mainly a graphite material, lithium ion intercalation/deintercalation occurs in the negative electrode material during charge and discharge cycles, and the negative electrode material has no obvious structural change and only can have the change of interlayer distance.

The crystal lattice of the graphene is hexagonal honeycomb-shaped, the internal linkage is very flexible due to the stable structure, and the structure endows the graphene with good mechanical stress performance; all carbon atoms in the crystal lattice are hybridized by sp2, and free electrons between the crystal lattices are dissociated, so that the graphene has excellent thermal and electrochemical properties; meanwhile, the thickness of the sheet layer is only one carbon atom, and the specific surface area of the graphene is 2630m²The/g means that the graphene sheet layer can store a large amount of lithium ions and electrons, and energy storage equipment with superior performance can be prepared; the single-layer graphene and the lithium metal can form an LiC3 structure, and the specific capacity reaches 744mAhg < -1 >, so E.J.Yoo et al introduce the graphene as a battery cathode material for the first time in 2008, the specific capacity can reach 540mAhg < -1 >, and the specific capacity is higher than that of commercial graphite but still smaller than a theoretical value; in addition, the rate performance is poor. This is mainly due to the large specific surface area of the graphene sheets, which makes the sheets easily agglomerate with each other, resulting in a decrease in effective area and thus a decrease in lithium intercalation sites, which leads to a specific capacity smaller than the calculated value and poor rate performance.

Disclosure of Invention

In order to improve the specific capacity of the lithium ion battery cathode material and the volume stability of the cathode material, the ZnS composite graphene oxide material prepared by the invention has a flower-bunch-shaped graphene layer, ZnS nano particles are attached to the surface of graphene, the graphene layers are not agglomerated, and the ZnS nano particles are small in size and are not agglomerated. The invention also provides a preparation method of the ZnS composite graphene oxide material, the obtained material has better performance required by the battery cathode material, the energy utilization efficiency is obviously improved, and the material also has excellent catalytic effect in photocatalytic degradation of methyl orange.

The invention has the technical conception that thermo-responsive polymers (NIPAAM-co-DMAAM) with specific molar ratio of NIPAAM and DMAAM are prepared by polymerizing thermo-sensitive materials N-isopropyl acrylamide and N, N-dimethyl acrylamide, Zn ions are adsorbed on the surface by graphene oxide, graphene oxide is adsorbed by DMAAM, Zn ions and graphene oxide are uniformly dispersed, sodium sulfide nonahydrate is dripped and uniformly mixed, the thermo-responsive polymers form a micro-reaction space wrapping the graphene oxide, the zinc ions and sulfur ions by heating, the graphene loaded with ZnS is prepared by hydrothermal reaction in the micro-reaction space, the ZnS is uniformly distributed on the surface of the graphene, the graphene has conductivity, the hollow structure brings buffer effect for volume change, the graphene is highly dispersed by the thermo-responsive polymers without agglomeration, so that the lithium embeddable sites are increased, the specific capacity is improved and the volume stability of the negative electrode material is increased.

The polymer can be used as a template agent, graphene oxide, metal salt and a thioreagent are dissolved in water, and metal sulfide based on the template morphology is prepared and uniformly dispersed on the surface of the graphene oxide. Therefore, the dispersion performance of the graphene oxide and the metal sulfide can be obviously improved.

In the thermally responsive polymer, a nitrogen atom of DMAAM is connected with a conjugated structure formed by-C-O and simultaneously connected with two methyl groups to form a super-conjugated structure, and the surface of the nitrogen atom is positively charged and mutually adsorbed with graphene with negative surface charge, so that the copolymer can be self-assembled with the graphene in water to form graphene-loaded hydrogel; the gel-swollen high molecular polymers prepared by the invention are mutually connected to form a three-dimensional space network structure, and a dispersion system of liquid media (graphene oxide, zinc ions and sulfur ions) is filled in gaps of the network structure, so that when the temperature of the environment changes, the volume of the gel changes, and sometimes phase transformation also occurs, and NIPAM (temperature sensitive material poly-N-isopropylacrylamide) is an amphiphilic polymer and is polymerized by a monomer N-isopropylacrylamide (NIPAM) through a high molecular method. The poly-N-isopropylacrylamide has hydrophilic acylamino and hydrophobic isopropyl at the same time, a hydrophilic/hydrophobic balance area exists, the interaction between copolymer gel and water is mainly amide groups and water at low temperature, water molecules around a macromolecular chain form a solvation shell layer which is connected by hydrogen bonds and has higher ordering degree, and the polymer molecular chain is dissolved in water; as the temperature rises, the intramolecular and intermolecular hydrophobic interactions strengthen each other, and the macromolecules begin to shrink due to the dehydration. When the temperature reaches LCST, the gel is subjected to violent dehydration, a solvation layer of a hydrophobic part of a macromolecular chain is damaged, and self-assembly forms with different appearances are formed due to shrinkage. The LCST can be increased or decreased when the hydrophilic and hydrophobic components in the polymer backbone are adjusted.

In order to achieve the purpose, the technical scheme of the invention is as follows: a three-dimensional flower bunch-shaped structure nano material compounded with zinc sulfide on graphene oxide comprises a three-dimensional flower bunch-shaped structure graphene oxide sphere, two-dimensional graphene oxide sheets positioned on the sphere and ZnS nano particles deposited on the surfaces of the two-dimensional graphene oxide sheets; the three-dimensional flower bunch-shaped structure nano material of the zinc sulfide compounded on the graphene oxide is prepared by adding the graphene oxide and Zn containing cations into an aqueous solution of a temperature-sensitive material PN80D4²⁺The soluble salt is evenly dispersed by ultrasonic, and then the soluble salt is added with S containing anions^2-Uniformly mixing the soluble salt, performing hydrothermal reaction on the mixed solution at the temperature of 120-160 ℃ to obtain a precipitate, and washing and centrifuging to remove the precipitate obtained from the temperature-sensitive material PN80D4, wherein the temperature-sensitive material PN80D4 is a temperature-sensitive material; graphene oxide, cation-containing Zn²⁺Soluble salt of (1)00mg, 2-6 mmol, containing Zn as cation²⁺With a soluble salt of S containing an anion^2-The mixing ratio of the soluble salt of (1): 2;

the temperature-sensitive material PN80D4 is poly N-isopropyl acrylamide-co-N, N-dimethyl acrylamide, 80 represents the polymerization degree of the N-isopropyl acrylamide, and 4 represents the polymerization degree of the N, N-dimethyl acrylamide.

Further, the diameter of the ZnS nano particle is 10-20 nm, the particle size of the graphene oxide sphere with the three-dimensional flower-bunch-shaped structure is 4-6 mu m, and the diameter of the two-dimensional graphene oxide sheet is 1-2.5 mu m.

Further, the three-dimensional flower bunch-shaped structure nano material compounded with zinc sulfide on graphene oxide is used for preparing a lithium ion battery, the three-dimensional flower bunch-shaped structure nano material compounded with zinc sulfide on graphene oxide is ground, sieved, mixed with Super-P-Li and polyvinylidene fluoride according to the mass ratio of 8:1:1, N-methyl pyrrolidone is added, stirred in a disc turbine stirrer to be viscous, slurry is poured on a current collector copper foil for coating, dried for 24 hours at 60 ℃ in a vacuum drying box, sliced to prepare a lithium ion battery electrode, finally, a seal is assembled in a glove box filled with argon to prepare a button type lithium ion battery, the battery measures a cyclic voltammetry curve under the conditions that the voltage range is 0.05-3V and the current density is 100mA/g, the battery cyclic efficiency is not less than 90 percent, and the specific capacity after 50 cycles is 802mAh/g, and the charging and discharging specific capacity curves are overlapped.

Further, the preparation method of the three-dimensional flower bunch-shaped structure nano material compounded with zinc sulfide on graphene oxide comprises the following steps:

(1) preparing a temperature-sensitive material PNxDy by adopting a free radical polymerization method or a controllable fracture chain transfer polymerization method, wherein the temperature-sensitive material PNxDy is poly-N-isopropyl acrylamide-co-N, N-dimethyl acrylamide, x represents the polymerization degree of the N-isopropyl acrylamide, x is 80, y represents the polymerization degree of the N, N-dimethyl acrylamide, and y is 4;

(2) dissolving PN80D4 serving as a template in deionized water to obtain hydrogel, and adding a graphene oxide material and Zn containing cations²⁺Is subjected to ultrasonic dispersion, and then is added with S containing anions^2-The soluble salt is mixed evenly, wherein the graphene oxide and the salt contain cation Zn²⁺The soluble salt is mixed according to 100mg: 2-6 mmol, and the soluble salt contains cation Zn²⁺With a soluble salt of S containing an anion^2-The mixing ratio of the soluble salt of (1): 2;

(3) and carrying out hydrothermal reaction on the mixed solution at the temperature of 120-160 ℃ to obtain a precipitate, washing with deionized water, washing with absolute ethyl alcohol, centrifuging, repeating the above operation for several times, removing the temperature-sensitive material PN80D4, and finally drying to obtain the graphene oxide-zinc sulfide-composited three-dimensional flower-bunch-structure nano material.

Preferably, in the preparation process of the temperature-sensitive material PN80D4 in step (1), AIBN is used as an initiator, N-isopropylacrylamide is a hydrophilic monomer, N-dimethylacrylamide is a hydrophobic monomer, and mercaptoethylamine hydrochloride is used as a capping agent.

Preferably, in the preparation process of the temperature-sensitive material in the step (1), anhydrous methanol is used as a reaction solvent, and nitrogen is used as a protective gas.

As a preferable scheme, in the preparation process of the temperature-sensitive material in the step (1), the reaction temperature is 60-80 ℃, and the reaction time is 12-24 hours. After the reaction was complete, diethyl ether was used as a precipitant to afford a white solid. The vacuum drying temperature is 30-60 ℃, and the drying time is 8-16 h.

Preferably, the graphene oxide in the step (2) is prepared by a Hummer method.

Preferably, the hydrothermal reaction in the step (3) is carried out under the conditions of 120-140 ℃ and the reaction time is 8-12 h.

As a preferred scheme, the three-dimensional flower bunch-shaped structure nano material compounded with zinc sulfide on the graphene oxide is applied as a photocatalyst.

Compared with the prior art, the invention has the following outstanding properties and remarkable advantages:

(1) the temperature-sensitive material is used as a template agent to provide a template for the forming of the zinc sulfide material, and the existence of the temperature-sensitive material can enhance the compatibility of various substances in the precursor, thereby being beneficial to preparing the composite material with controllable thickness and uniform and complete appearance.

(2) Compared with the existing zinc sulfide material, the battery cathode material containing the temperature-sensitive material prepared by the invention has more excellent electrochemical performance and better reversible capacity, and the ZnS composite graphene oxide material shows good electrochemical performance, so that the ZnS material with controllable morphology (the flower bunch shape is optimal) can be obtained by taking the temperature-sensitive material PN80D4 as a template and the graphene oxide as a carrier material, and meanwhile, the graphene oxide can be uniformly dispersed in a polymer PN80D4 matrix due to the hydrogen bond action of oxygen-containing functional groups on the graphene oxide and a polymer PN80D4 molecular chain, so that the response speed of electron conduction is greatly improved; in addition, the growth of zinc sulfide particles is limited due to the addition of the graphene, the particles with smaller particle sizes have larger specific surface areas, the particles can be more fully contacted with electrolyte, more reaction sites are generated, the diffusion path of lithium ions is shortened to a certain extent due to the small particle sizes, and the performance of the electrode material under the condition of large-current charging and discharging can be improved. Meanwhile, the small-particle zinc sulfide material can better relieve stress concentration caused by the volume effect of the transition metal sulfide material, and prevent the material from being rapidly pulverized. From the perspective of long-term development, the application and development of the ZnS composite graphene oxide material in the lithium ion battery are worth researching and discussing.

Due to the fact that the graphene and the polymer PN80D4 are compounded with zinc sulfide, high conductivity is provided for an electrode material, the characteristics of the graphene and the polymer PN80D4 can be used as a buffer component, volume change and agglomeration and stacking of graphene sheets are effectively relieved, the shape controllable structure of the material is kept, meanwhile, the sensitive electrochemical performance and temperature sensitivity are obtained through the synergistic effect of the graphene oxide and the polymer PN80D4, and an effective way is hopefully provided for performance breakthrough of a new-generation lithium ion battery cathode material.

(3) According to the invention, the temperature-sensitive material is used as the template, the shape of the zinc sulfide composite graphene oxide material is controllable, the process flow is easy to implement, the control is accurate, and the repeatability is high.

Drawings

FIG. 1 shows TEM morphology of temperature-sensitive material PNxDy

FIG. 2 is an SEM representation of a pure zinc sulfide material;

FIG. 3 shows TEM characteristics and XRD patterns of a ZnS composite graphene oxide material prepared by a hydrothermal method after adding a temperature-sensitive material PN80D4 as a template;

FIG. 4 is a cyclic voltammogram of a pure ZnS composite graphene oxide material as a battery cathode material when a temperature-sensitive material PN80D4 is not added as a template;

FIG. 5 is a cyclic voltammogram of the ZnS composite graphene oxide material obtained after adding a temperature sensitive material PN80D4 as a template as a battery negative electrode material;

fig. 6 is a graph of degradation performance of a methyl orange degradation experiment using a temperature sensitive material PNxDy as a template and the obtained ZnS composite graphene oxide material as a photocatalyst, wherein curves from top to bottom in the graph correspond to illumination for 10min, 30min, 60min, 90min and 120min in sequence;

FIG. 7 is a schematic flow diagram of the preparation of a lithium ion battery;

FIG. 8 is a scanning electron microscope image of pure ZnS nanoparticles prepared without adding graphene oxide, by mixing only zinc acetate dihydrate and sodium sulfide nonahydrate into an aqueous solution of a temperature-sensitive material PN80D4 in proportion under hydrothermal reaction conditions;

FIG. 9 is an enlarged partial view of FIG. 8;

fig. 10 is a scanning electron microscope image of the ZnS composite graphene oxide material prepared from the PN70D7 template;

fig. 11 is a cyclic voltammogram of a ZnS composite graphene oxide material prepared from a PN70D7 template;

fig. 12 is a scanning electron microscope image of the ZnS composite graphene oxide material prepared from the PN90D3 template;

fig. 13 is a cyclic voltammogram of the ZnS composite graphene oxide material prepared from the PN90D3 template;

fig. 14 is a scanning electron microscope image of the ZnS composite graphene oxide material prepared from the PN90D0 template;

fig. 15 is a cyclic voltammogram of the ZnS composite graphene oxide material prepared from the PN90D0 template.

Detailed Description

For a better understanding of the present invention, reference will now be made in detail to the present invention, which is illustrated in the accompanying drawings and specific examples. The method specifically comprises the steps of preparing a pure nano ZnS composite graphene oxide material, preparing a temperature-sensitive material serving as a template and the ZnS composite graphene oxide material, and testing the electrochemical performance and the photocatalytic performance of the material.

Synthesizing a pure ZnS composite graphene oxide material by a hydrothermal method:

adding 100mg of graphene oxide into 60ml of deionized water, performing ultrasonic dispersion uniformly, adding zinc acetate dihydrate into the solution, dropwise adding ammonia water, and adjusting the pH value to 9. And then adding 0.3-0.6 mmol/ml of sodium sulfide nonahydrate aqueous solution into the solution under magnetic stirring. And after fully mixing, transferring the mixture into a polytetrafluoroethylene reaction kettle, filling 3/4 of the total volume, screwing down and sealing the reaction kettle, and adjusting the temperature to 100-140 ℃ for heating for 10 hours. Wherein the zinc acetate dihydrate and the sodium sulfide nonahydrate are mixed according to the proportion of 1: 2, the addition ratio of zinc acetate dihydrate to graphene oxide is 1.5-3 mmol: 100mg, after the reaction is finished, naturally cooling the reaction kettle to room temperature, taking out the solution, centrifuging to obtain white precipitate, washing with absolute ethyl alcohol and distilled water for 3 times respectively, and drying in vacuum for 4 hours to obtain a black powder product, namely the nano zinc sulfide ZnS composite graphene oxide.

Comparative examples 1 to 9

According to the implementation conditions of table 1, pure ZnS composite graphene oxide material was synthesized according to a hydrothermal method, and the addition amounts of zinc acetate dihydrate and sodium sulfide nonahydrate in each proportion were different, and the reaction temperatures in the reaction kettle were different.

TABLE 1 samples prepared by different experimental factors in the synthesis of ZnS nanoparticles by hydrothermal method

Hydrothermal method conditions: 15ml of water and 20ml of glycol for 10 hours

As shown in fig. 2, which is an SEM scanning electron micrograph of the ZnS composite graphene oxide material prepared by the hydrothermal method in comparative example 5, and a in fig. 2, which is a partial view of b, it can be seen that spherical pure zinc sulfide nanoparticles are obtained, the nanoparticles have a diameter of 4 to 5 μm and a large size, and graphene oxide sheets are stacked together with some agglomeration. And (3) respectively preparing the materials in the comparative examples 1-9 into button lithium ion batteries, and then carrying out constant-current charge-discharge test on the lithium ion batteries to test the electrochemical performance of the lithium ion batteries. Grinding and sieving the high-quality sample prepared in the comparative example 5, mixing the high-quality sample with Super-P-Li (conductive carbon black) and PVDF (polyvinylidene fluoride) according to the mass ratio of 8:1:1, adding NMP (N-methyl pyrrolidone) and stirring the mixture in a disc turbine stirrer to be viscous, pouring the slurry on a current collector copper foil for coating, placing the current collector copper foil in a vacuum drying box for drying at 60 ℃ for 24 hours, slicing the current collector copper foil to prepare a lithium ion battery electrode, and finally assembling and sealing the current collector copper foil in a glove box filled with argon to prepare the button type lithium ion battery. The flow diagram is shown in fig. 7.

The prepared material is subjected to cyclic voltammetry test by a blue battery test system (model blue and CT2001A), the experimental voltage range is 0.05-3V, the current density is 100mA/g, and the cyclic voltammetry curve of the obtained material is tested.

Examples 1 to 3:

preparing a ZnS composite graphene oxide nano composite material by a hydrothermal method by taking a temperature-sensitive material PNxDy as a template:

the temperature-sensitive material PNxDy is synthesized by a reversible addition-fragmentation chain transfer (RAFT) polymerization technology, and the synthesis steps of poly (NIPAAM-co-DMAAM) are as follows:

the monomers of NIPAAM and DMAAM were dissolved in anhydrous methanol in a Schlenk reaction tube in different molar ratios as in table 2 and N, N-azobis (isobutyronitrile) (AIBN) (0.5mmol, 0.082g) and 2-aminoethanethiol hydrochloride (1mmol, 0.077g) were added to the solution as free radical initiator and chain transfer agent. The reaction mixture was degassed by bubbling nitrogen at room temperature for 30 minutes. The polymerization was carried out at 60 ℃ under a nitrogen atmosphere for 24 hours. The mixture was then cooled to room temperature and then treated with solid KOH (1mmol, 0.056 g). The resulting solution was concentrated under vacuum. The crude product was precipitated repeatedly from diethyl ether and then unreacted monomers were removed from tetrahydrofuran. After vacuum drying at room temperature for 24 hours, white powdery copolymers were obtained, expressed as PNxDy (where x represents the number of recurring units for NIPAM and y represents the number of recurring units for DMAAM; x and y were determined from the 1H NMR spectra of the corresponding copolymers different molar feed ratios (91/9, 95/5 and 97/3) gave copolymers of PN70D7, PN80D4 and PN90D3, respectively.

TABLE 2

	NIPAAM(mmol)	DMAAM(mmol)	Polymer and method of making same	Morphology of
					Example 1	91	9	PN70D7	Vesicle
Example 2	95	5	PN80D4	Rod-like
					Example 3	97	3	PN90D3	Small particles
Blank control	100	0	PN90D0	Spherical shape

The morphology is shown in FIG. 1

The reaction route is as follows:

according to the reaction route, 2-aminoethanethiol hydrochloride is taken as a chain transfer agent, and the amino-terminated (ANH) on a DMAAM chain is prepared by the RAFT technology₂) A poly (NIPAAMco-DMAAM) amphiphilic diblock copolymer of radicals. 1H NMR spectroscopy was used to compare the signal of the individual blocks (NIPAAM about 1.09ppm, DMAAM about 2.96-3.12 ppm) with terminal methylene groups (ACH)₂ACH₂ANH₂) (about 2.72ppm) to determine the degree of polymerization of the individual NIPAAM and DMAAM blocks. The molar ratio of NIPAAM to DMAAM in poly (NIPAAM-co-DMAAM) was also distinguished in the 1H NMR spectrum.

As the blank in fig. 1 and the copolymers of examples 1-3 and graphene oxide showed extensive ordered morphology after water-soluble mixing, the DMAAM-free counterpart of PN90D0 formed spherical aggregates (part a in fig. 1) with an average diameter of 25nm, the much smaller aggregate size (about 7nm) of PN90D3 (part b in fig. 1) may be due to the reduced hydration of the PNIPAAM chains in PN90D 3. Further increasing the molar ratio of DMAAM to NIPAAM in poly (NIPAAM-co-DMAAM) from 1/30 to 1/20 formed a self-assembly of rods with an average length of about 100nm, the ordered morphology of the PN80D4 surface (part c in fig. 1) provided a rod-like restricted microenvironment for graphene. When the molar ratio of DMAAM to NIPAAM in poly (NIPAAM-co-DMAAM) was increased to 1/10, unilamellar vesicles were observed on PN70D7, and the aggregates were not uniform in size (part D in fig. 1), with the inner portion of the bubble-like structure containing water therein surrounded by a membrane. The results show that the ratio of hydrophilicity to hydrophobicity in poly (NIPAAM-co-DMAAM) modulates the self-assembled morphology of the interpolymer in water. The different morphologies of the interpolymers depend on a balance of two opposing forces: polar repulsion between hydrophilic chains and hydrophobic interactions between hydrophobic groups.

The following graphene oxide was produced by a hummers method, and the steps were as follows:

1, taking 5g of graphite powder and 2.5g of NaNO₃Adding into 150ml of concentrated sulfuric acid, and stirring for 15min in an ice water bath;

2, slowly adding 15g of KMnO₄(the temperature is lower than 20 ℃), stirring in an ice-water bath for 2 hours, and changing the reaction system into dark green;

3, heating to 35 ℃, reacting for 30min, and adding 200ml of water;

4, moving the mixture into an oil bath at the temperature of 98 ℃, and reacting for 90min to ensure that the reaction system turns into dark yellow;

5, diluting to 500ml with water at 60 deg.C, adding 35ml of H₂O₂Releasing a large amount of bubbles in the reaction system, changing the color into bright yellow, filtering while the solution is hot, washing the solution by using a 5% HCl solution and deionized water until no sulfate radical is detected in the filtrate, and finally placing the filter cake in a vacuum drying oven at 60 ℃ for full drying and storing for later use.

Weighing 0.050g of temperature-sensitive material PN80D4, dissolving in 10mL of deionized water, fully dissolving, adding 100mg of graphene oxide into 60mL of deionized water, performing ultrasonic homogenization, adding zinc acetate dihydrate into the solution, and performing ultrasonic homogenization for 1h to form a uniform solution. Ammonia was added dropwise to adjust the pH to 9. And then 0.4-1.2 mmol/ml of sodium sulfide nonahydrate aqueous solution is added into the solution under magnetic stirring. And after fully mixing, transferring the solution into a 100ml high-pressure reaction kettle, heating to 120-160 ℃, keeping for 10h, naturally cooling to room temperature, washing the obtained hydrogel with acetic acid and deionized water to dissolve the temperature-sensitive material PN80D4, centrifuging to separate the ZnS composite graphene oxide material, and drying. Wherein the zinc acetate dihydrate and the sodium sulfide nonahydrate are mixed according to the proportion of 1: 2, and the addition ratio of zinc acetate dihydrate to graphene oxide is 2-6 mmol: 100 mg.

According to the implementation conditions of table 3, a temperature-sensitive material PN80D4 is used as a template, and a ZnS composite graphene oxide material is synthesized according to a hydrothermal method, wherein the addition amounts of zinc acetate dihydrate and sodium sulfide nonahydrate in each example are different, the reaction temperature in a reaction kettle is different, and graphene oxide is not added in example 13. Fig. 3 shows SEM scanning electron micrographs and XRD patterns of the ZnS composite graphene oxide material prepared by hydrothermal method in example 8. Part a in fig. 3 shows that the prepared ZnS composite graphene oxide material has a more excellent morphology and is in a flower bunch shape. Part b in fig. 3 shows that the ZnS composite graphene oxide material contains ZnS and graphene oxide, the graphene oxide is distributed on a flocculent carrier composed of a temperature-sensitive material PN80D4 in a three-dimensional flower-bunch structure, and the carrier and the ZnS composite graphene oxide material can be separated by washing and centrifuging, for example, in fig. 3, the particle size of the graphene oxide in the three-dimensional flower-bunch structure is 4-6 μm, the two-dimensional graphene oxide sheet forms petals of the three-dimensional flower-bunch structure, the diameter of the two-dimensional graphene oxide sheet is 1-2.5 μm, as shown in fig. 8 and 9, the graphene oxide is not added, only zinc acetate dihydrate and sodium sulfide nonahydrate are mixed into an aqueous solution of the temperature-sensitive material PN80D4 according to a proportion, pure nanoparticles are prepared under the hydrothermal reaction condition, and the ZnS grow into an irregular rod-shaped material according to a PN80D4 template, and have the diameter of about 1 μm and the length of 10 μm. Therefore, in the preparation process of the ZnS composite graphene oxide material of embodiment 8, PN80D4 disperses the graphene oxide sheets, and the graphene oxide sheets further disperses the ZnS particles, so that the size of the ZnS particles is prevented from reaching 10nm level, which is much smaller than the ZnS particles (50nm level) in the ZnS reduced graphene oxide composite material prepared in the "preparation and photocatalytic performance of ZnS/reduced graphene oxide composite material" in the prior art. Meanwhile, compared with the Zn graphene oxide composite material (shown in figure 2) prepared by a template-free hydrothermal method, no obvious agglomeration phenomenon is found in graphene oxide sheets, a part b in figure 2 shows that the graphene oxide sheets have a certain stacking degree, and ZnS particles are not uniformly dispersed on the graphene oxide sheets.

Table 3 samples prepared by different experimental factors in synthesis of ZnS nanoparticles by hydrothermal method with temperature-sensitive material PN80D4 as template

Hydrothermal method conditions: 15ml of water and 20ml of glycol for 10 hours

The two materials in the embodiments 4-13 are respectively prepared into button lithium ion batteries, and then the lithium ion batteries are subjected to constant current charge and discharge tests to test the electrochemical performance of the lithium ion batteries. Grinding and sieving a high-quality sample prepared by reaction, mixing the high-quality sample with Super-P-Li (conductive carbon black) and PVDF (polyvinylidene fluoride) according to the mass ratio of 8:1:1, adding NMP (N-methyl pyrrolidone) and stirring the mixture in a disc turbine stirrer to be viscous, pouring the slurry on a current collector copper foil for coating, placing the current collector copper foil in a vacuum drying box for drying at 60 ℃ for 24 hours, slicing the current collector copper foil to prepare a lithium ion battery electrode, and finally assembling and sealing the current collector copper foil in a glove box filled with argon to prepare the button type lithium ion battery. The flow diagram is shown in fig. 7.

The prepared material is subjected to cyclic voltammetry test by a blue battery test system (model blue and CT2001A), the experimental voltage range is 0.05-3V, the current density is 100mA/g, and the cyclic voltammetry curve of the obtained material is tested.

Fig. 4 and 5 are cyclic voltammograms corresponding to comparative example 5 and example 8, respectively, the cyclic curves of ZnS materials different in comparative example and example show different specific capacities, both materials have very high first discharge specific capacities, and the battery cyclic efficiency is above 90%. FIG. 4 is a cyclic voltammogram of pure ZnS material prepared by hydrothermal method, and its specific capacity is about 536 mAh/g. FIG. 5 is a circuit diagram of a cycle of preparing ZnS composite graphene oxide material by a hydrothermal method with a temperature-sensitive material PN80D4 as a template, the battery cycle efficiency reaches about 93%, and the capacity can still maintain 802mAh/g after 50 cycles. The battery cycle efficiency of the lithium batteries manufactured by the samples in the embodiments 4 to 12 can exceed 90%, the charge-discharge specific capacity curves are almost overlapped in 50 charge-discharge processes, the capacity ratio is close to 1:1, and comprehensively, the electrochemical performance of the ZnS composite graphene oxide material prepared by using the temperature-sensitive material PN80D4 as the template is superior to that of the pure ZnS composite graphene oxide material.

Example 14

The catalyst with excellent morphology prepared in the above example 8 is used in an experiment for photocatalytic degradation of methyl orange, and the specific operations are as follows: preparing 20mg/L methyl orange solution, measuring 100ml of the solution in a reaction tube, and adding a certain amount of catalyst powder material into the reaction tube. Stirring and dispersing for 20min in dark to ensure that the methyl orange is completely pre-adsorbed on the surface of the catalyst, then placing the catalyst in a photocatalytic reactor, starting circulating water, and irradiating under an ultraviolet lamp for a certain time. After the reaction is finished, the solid catalyst is separated by high-speed centrifugation, and supernatant fluid is taken. And (3) performing full-wavelength scanning on the methyl orange within the range of 200-800nm by using an ultraviolet-visible spectrophotometer, selecting the optimal detection wavelength to measure the absorbance of the methyl orange, and calculating the degradation rate.

As can be seen from FIG. 6, the material has good photocatalytic performance in methyl orange, and the photocatalytic degradation efficiency can reach 96% after 2h of light reaction.

Comprehensive analysis shows that the ZnS composite graphene oxide composite material prepared by taking the temperature-sensitive material PN80D4 as a template has such excellent electrochemical performance, mainly due to the template effect of a polymer (PN80D4), and the ZnS is tested to be uniformly distributed on the surface of the graphene oxide to form nano-particles with uniform size. After zinc particles, sulfide ions and graphene oxide are coated by a polymer (PN80D4), the zinc particles, the sulfide ions and the graphene oxide can be well dispersed in water; the existence of the graphene not only provides a quick electronic transmission channel for the electrode material, greatly improves the performance of the material under heavy current charge and discharge, but also can effectively relieve stress concentration caused by the volume effect of the zinc sulfide material in the repeated charge and discharge process, well inhibits the pulverization and the falling of the electrode material, and thus greatly improves the cycle stability of the composite material. The effective compounding of the polymer (PN80D4) and the graphene is a method for effectively improving the electrochemical performance of the zinc sulfide material. In addition, the photocatalysis experiment result also shows that the material has wide application prospect in photocatalysis and has potential application value in treating industrial wastewater.

Examples 15 to 17

Weighing 0.050g of the temperature-sensitive material PNxDy in Table 4, dissolving in 10mL of deionized water, fully dissolving, adding 100mg of graphene oxide into 60mL of deionized water, performing ultrasonic homogenization, adding 4mmol of zinc acetate dihydrate into the solution, and performing ultrasonic homogenization for 1h to form a uniform solution. Ammonia was added dropwise to adjust the pH to 9. 8mmol of sodium sulfide nonahydrate was dissolved in 10ml of deionized water and added to the solution under magnetic stirring. And after fully mixing, transferring the solution into a 100ml high-pressure reaction kettle, heating to 140 ℃ for 10h, naturally cooling to room temperature, washing the obtained hydrogel with acetic acid and deionized water to dissolve the temperature-sensitive material PNxDy, centrifuging to separate out the ZnS composite graphene oxide material, and drying.

According to the implementation conditions of table 4, a temperature-sensitive material PNxDy is used as a template, a ZnS composite graphene oxide material is synthesized according to a hydrothermal method, the addition amounts of zinc acetate dihydrate and sodium sulfide nonahydrate in the examples are the same, and the reaction temperature in a reaction kettle is the same.

TABLE 4 samples prepared by different experimental factors in synthesizing ZnS nanoparticles by hydrothermal method with temperature sensitive material PN80D4 as template

Hydrothermal method conditions: 15ml of water and 20ml of glycol for 10 hours

And (3) respectively preparing the materials in the embodiments 15-17 into button lithium ion batteries, and then carrying out constant-current charge-discharge test on the lithium ion batteries so as to test the electrochemical performance of the lithium ion batteries. Grinding and sieving a high-quality sample prepared by reaction, mixing the high-quality sample with Super-P-Li (conductive carbon black) and PVDF (polyvinylidene fluoride) according to the mass ratio of 8:1:1, adding NMP (N-methyl pyrrolidone) and stirring the mixture in a disc turbine stirrer to be viscous, pouring the slurry on a current collector copper foil for coating, placing the current collector copper foil in a vacuum drying box for drying at 60 ℃ for 24 hours, slicing the current collector copper foil to prepare a lithium ion battery electrode, and finally assembling and sealing the current collector copper foil in a glove box filled with argon to prepare the button type lithium ion battery.

The prepared material is subjected to cyclic voltammetry test by a blue battery test system (model blue and CT2001A), the experimental voltage range is 0.05-3V, the current density is 100mA/g, and the cyclic voltammetry curve of the obtained material is tested.

Fig. 10 is a scanning electron microscope image of the ZnS composite graphene oxide material prepared by using the PN70D7 template, it can be seen that ZnS nanoparticles are flaky, fig. 11 is a cyclic voltammogram of the ZnS composite graphene oxide material prepared by using the PN70D7 template, the battery cycle efficiency reaches about 94%, and the capacity can still maintain 603mAh/g after 50 cycles. Fig. 12 is a scanning electron microscope image of the ZnS composite graphene oxide material prepared by using the PN90D3 template, which shows that ZnS nanoparticles are flaky and have a particle size of 3-4 μm, fig. 13 is a cyclic voltammogram of the ZnS composite graphene oxide material prepared by using the PN90D3 template, the battery cycle efficiency reaches about 94%, and the capacity can still maintain 640mAh/g after 50 cycles. Fig. 14 is a scanning electron microscope image of the ZnS composite graphene oxide material prepared by using the PN90D0 template, which shows that ZnS nanoparticles are ellipsoidal and have a particle size of 5-8 μm, fig. 15 is a cyclic voltammogram of the ZnS composite graphene oxide material prepared by using the PN90D3 template, the battery cycle efficiency reaches about 94%, and the capacity can still be maintained at 645mAh/g after 50 cycles. The specific capacity of the ZnS composite graphene oxide material prepared by a hydrothermal method by using the temperature-sensitive material PN80D4 as a template is higher than that of the ZnS composite graphene oxide material obtained in the embodiments 15 to 17, probably because the specific surface area of ZnS particles with small sizes attached to graphene oxide with a three-dimensional flower-bunch-shaped structure is larger, so that more lithium intercalation sites are provided, and the specific surface area of the ZnS composite graphene oxide material obtained in the embodiments 15 to 17 is flaky or ellipsoidal, so that the specific surface area is obviously reduced.

The embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to the embodiments, and various changes and modifications can be made according to the purpose of the invention, and any changes, modifications, substitutions, combinations or simplifications made according to the spirit and principle of the technical solution of the present invention shall be equivalent substitution ways, so long as the purpose of the present invention is met, and the present invention shall fall within the protection scope of the present invention as long as the technical principle and inventive concept of the preparation method of the temperature-sensitive ZnS composite graphene oxide composite nanomaterial and the application thereof are not deviated from. Therefore, the protection scope of the present patent shall be subject to the appended claims.