CN109748327B - A method for preparing CuCoO2 nanocrystalline materials at low temperature based on MOFs materials - Google Patents

Abstract

The invention relates to a method for preparing nano CuCoO by synthesis at a lower temperature by using a hydrothermal method₂A method of crystallizing a material. MOFs material-based CuCoO for preparing delafossite structure at low temperature₂The method for preparing the nanocrystalline material is characterized by comprising the following steps of: preparing a reaction precursor by taking a Metal Organic Framework (MOFs) material as an initial reactant, putting the reaction precursor into a hydrothermal reaction kettle, carrying out hydrothermal reaction at 100-140 ℃ for 24-48 hours, carrying out centrifugal cleaning treatment on a reaction product to obtain a precipitate, and drying the precipitate to obtain the CuCoO with a delafossite structure of 50-200 nm size₂A nanocrystalline material. The method has the characteristics of simple operation, easy control of process parameters, no pollution, high yield, low temperature and high speed; can be widely used in various novel photoelectric functional devices.

Description

A method for preparing CuCoO2 nanocrystalline materials at low temperature based on MOFs materials

technical field

The invention relates to the field of synthesis and preparation of MOFs materials (Metal Organic Frameworks, metal organic framework materials) and nanomaterials, in particular to a method for synthesizing and preparing nanoscale delafossite-structured CuCoO ₂ crystal materials using a hydrothermal method at a lower reaction temperature.

Background technique

The delafossite-type oxides (ABO ₂ , A=Cu, Ag, etc., B=Al, Ga, Cr, Co or La, etc.) are an important class of transition metal oxide materials. In 1997, Prof. Hosono from Tokyo Institute of Technology and others reported the p-type conductivity of CuAlO ₂ thin film for the first time in Nature, and its room temperature conductivity was 9.5×10 ^-2 s·cm ^-1 . Inspired by the design idea of the chemical valence band of CuAlO ₂ , a series of ABO ₂ structural materials have become the focus of scientific researchers. The delafossite-structured ABO ₂ has a hexagonal layered crystal structure. Due to the different stacking of the common edge octahedron of BO ₆ , the delafossite-structured oxide ABO ₂ has two crystal forms, 2H and 3R. As a typical p-type semiconductor material, a series of ABO ₂ materials have been widely reported in the fields of optoelectronic devices such as transparent conductive oxides, solar cell devices, and photo/electrocatalysts.

由于铜3d轨道和氧2p轨道的杂化，导致氧原子在价带边局域化，且六角密排的铜层是其主要的导电层，所以该材料具有较大的光学带隙宽度和较高的电导率，在光电器件领域中有着良好的应用前景。目前，国内外对CuCoO₂材料的研究报道较少，一般通过离子交换反应或高温固相反应可以制备出CuCoO₂晶体材料。但是反应时间过长或者反应温度过高，会导致CuCoO₂材料晶体尺寸较大、反应效率低。比如，2010年，M.Beekman等人通过CuCl和LiCoO₂之间简单的离子交换固态反应，在590℃下反应48小时后，制备出多晶铜铁矿氧化物 CuCoO₂材料。2013年，RuttanapunC等人在高温1005℃下，采用常规固相反应法合成铜铁矿结构CuCoO₂晶体材料。与传统的离子交换反应法或者高温烧结法相比，水热法将反应物置于特殊的环境下(密闭、高压等)发生合成反应，避免了高温煅烧和球磨两项复杂的实验操作，可以大幅提高产物合成效率，广泛应用于纳米结构晶体材料合成领域。申请人课题组于2017年利用低温水热法，首次在反应温度为100℃时合成制备出2微米大小的 CuCoO₂晶体材料，并对其电解水析氧活性进行研究。但由于CuCoO₂晶体材料尺寸较大，比表面积较小导致其活性位较少，其电解水活性仍然有待提高。此外，由于纳米级p型半导体ABO₂材料合成制备非常困难，ABO₂纳米晶材料的匮乏严重制约该系列材料的光电器件应用研究。目前只有CuGaO₂、CuCrO₂、CuAlO₂、CuMnO₂、AgCrO₂等几种纳米晶材料的相关报道，暂未发现关于水热法合成纳米级CuCoO₂晶体材料的研究报道。因此，急需探索研发利用新的材料合成方法，以有效调控其晶体微观形貌和尺寸，制备出高质量的 CuCoO₂纳米晶材料。所以，研究利用水热法制备CuCoO₂纳米晶材料是非常新颖的，对于探索制备p型ABO₂纳米晶材料及其器件应用具有十分重要的研究意义。CuCoO ₂ material is a new type of cheap and environmentally friendly ABO ₂ material. In the lattice of the 3R _delafossite phase CuCoO2, Cu has a close-shell d10 structure, a layered structure in which O-Cu-O layers with dumbbell-like linear structure and _CoO6 co-edge octahedral layers are alternately stacked. Unit cell parameters of CuCoO ₂ in 3R crystal form

Due to the hybridization of copper 3d orbitals and oxygen 2p orbitals, the oxygen atoms are localized at the valence band edge, and the hexagonal close-packed copper layer is the main conductive layer, so the material has a large optical band gap width and relatively The high electrical conductivity has a good application prospect in the field of optoelectronic devices. At present, there are few research reports on CuCoO ₂ materials at home and abroad. Generally, CuCoO ₂ crystal materials can be prepared by ion exchange reaction or high temperature solid-phase reaction. However, if the reaction time is too long or the reaction temperature is too high, the crystal size of the CuCoO ₂ material will be large and the reaction efficiency will be low. For example, in 2010, M. Beekman et al. prepared polycrystalline delafossite oxide CuCoO ₂ material after a simple ion-exchange solid-state reaction between CuCl and LiCoO ₂ at 590 °C for 48 hours. In 2013, Ruttanapun C et al. synthesized the delafossite-structured CuCoO ₂ crystal material by a conventional solid-phase reaction method at a high temperature of 1005 °C. Compared with the traditional ion exchange reaction method or high temperature sintering method, the hydrothermal method places the reactants in a special environment (sealed, high pressure, etc.) for the synthesis reaction, avoiding the two complicated experimental operations of high temperature calcination and ball milling, and can greatly improve Product synthesis efficiency, widely used in the field of nanostructured crystal material synthesis. In 2017, the applicant's research group used a low-temperature hydrothermal method to synthesize and prepare a 2-micron-sized CuCoO ₂ crystal material for the first time at a reaction temperature of 100 °C, and studied its oxygen evolution activity in water electrolysis. However, due to the large size and small specific surface area of CuCoO ₂ crystal material, its active sites are less, and its water electrolysis activity still needs to be improved. In addition, because the synthesis and preparation of nano-scale p-type semiconductor ABO ₂ materials is very difficult, the lack of ABO ₂ nanocrystalline materials seriously restricts the application of this series of materials in optoelectronic devices. At present, there are only relevant reports on several nanocrystalline materials such as CuGaO ₂ , CuCrO ₂ , CuAlO ₂ , CuMnO ₂ , AgCrO ₂ , etc., and no research report on the synthesis of nano-scale CuCoO ₂ crystal materials by hydrothermal method has been found. Therefore, it is urgent to explore, develop and utilize new material synthesis methods to effectively control the microscopic morphology and size of the crystals and prepare high-quality CuCoO ₂ nanocrystalline materials. Therefore, it is very novel to study the preparation of CuCoO ₂ nanocrystalline materials by hydrothermal method, which is of great significance for exploring the preparation of p-type ABO ₂ nanocrystalline materials and their device applications.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a method for preparing a delafossite structure CuCoO ₂ nanocrystalline material at a low temperature, and the method has the characteristics of low temperature and high speed.

In order to achieve the above object, the technical scheme adopted in the present invention is: a method for preparing nanoscale delafossite structure CuCoO ₂ crystal material at low temperature, which is characterized by comprising the following steps: using MOFs material as a Cu or Co source starting reactant to prepare the reaction precursor (or hydrothermal reaction precursor, that is, using the MOFs material containing Cu or Co as the starting reactant to prepare the reaction precursor), put the reaction precursor into the hydrothermal reaction kettle, at 100 ~ 140 After the hydrothermal reaction is carried out at ℃ for 24 to 48 hours, the reaction product is subjected to centrifugal cleaning to obtain a precipitate, and the precipitate is dried to obtain a delafossite-structured CuCoO ₂ crystal material (a CuCoO ₂ crystal with a crystal size of about 50 to 200 nm). Material.

According to the above technical scheme, the preparation method of the reaction precursor is as follows: the Co source reactant and the Cu source reactant are added to a mixed solution of deionized water and absolute ethanol according to a mass ratio of 1:1 to 1.3, and the deionized water The volume ratio to absolute ethanol is 1:0.4-3.0. After the magnetic stirrer is fully stirred and dissolved (stirring for 10-15 minutes), NaOH with 10-50 times the mass of Co source reactant or Cu source reactant is added as a mineral. The chemical agent is fully stirred until the dissolution is complete, and the reaction precursor is obtained.

Specifically, the preparation method of the reaction precursor is one of the following three (the volume ratio of deionized water and absolute ethanol is 1:0.4-3.0):

1) Add the MOFs material of Co and the Cu-based compound to the mixed solution of deionized water and absolute ethanol according to the mass ratio of 1:1-1.3, after stirring and dissolving, then add the MOFs material of Co or the Cu-based compound with a mass of 10-50 times NaOH as a mineralizer, stirring until the dissolution is complete to obtain the reaction precursor;

2) Add the Co-based compound and the Cu MOFs material to the mixed solution of deionized water and absolute ethanol according to the mass ratio of 1:1-1.3, and after stirring and dissolving, then add the Co-based compound or the Cu MOFs material with a mass of 10-50 times NaOH as a mineralizer, stirring until the dissolution is complete to obtain the reaction precursor;

3) Add the MOFs material of Co and the MOFs material of Cu to the mixed solution of deionized water and absolute ethanol according to the mass ratio of 1:1-1.3, after stirring and dissolving, then add the MOFs material of Co or the MOFs material of Cu mass 10 ~50 times of NaOH was used as a mineralizer, and the mixture was stirred until it was completely dissolved to obtain a reaction precursor.

According to the above technical solution, the Cu source reactant is a compound containing Cu ²⁺ {such as an aqueous solution of Cu(NO ₃ ) ₂ , CuSO ₄ , etc.}, or a MOFs material containing Cu.

According to the above technical solution, the Co reactant is a Co ²⁺ -containing compound {such as Co(NO ₃ ) ₂ , CoSO ₄ and other aqueous solutions}, or a Co-containing MOFs material.

According to the above technical scheme, in the hydrothermal reaction, the reaction solution in the hydrothermal reaction kettle is a mixed solution of deionized water and absolute ethanol, which is composed of: the volume ratio of deionized water and absolute ethanol is 1:0.4～3.0, The resistivity of deionized water is 18.24MΩ·cm (25°C), and its filling rate is 60-75%.

According to the above technical scheme, the centrifugal cleaning method is as follows: the reaction product is centrifugally cleaned in the order of deionized water, dilute NH ₃ ·H ₂ O (mass fraction 1-10%), and absolute ethanol. The order of the centrifugal cleaning solution can be adjusted (centrifugal cleaning such as deionized water, dilute NH ₃ ·H ₂ O, deionized water, anhydrous ethanol, etc. can also be used).

According to the above technical scheme, the centrifugal cleaning method is as follows: centrifugal cleaning is performed in the order of dilute NH ₃ ·H ₂ O (mass fraction 1-10%), deionized water, and absolute ethanol.

According to the above technical scheme, the drying is as follows: drying the precipitate after centrifugal cleaning treatment in a vacuum drying oven at 60° C. for 4 to 12 hours.

The above-mentioned application of preparing the delafossite structure CuCoO ₂ nanocrystalline material at low temperature is characterized in that it is used in various optoelectronic functional devices as a novel semiconductor working electrode material.

According to the above technical scheme, the application in various optoelectronic functional devices is as follows: in solar cells, electrolyzed water, photoelectrolyzed water or photocatalytic devices.

The invention utilizes low-temperature hydrothermal reaction to control and control the parameters including reaction precursor components, reaction temperature and the filling rate parameter of the reaction solution in the hydrothermal reaction kettle, and prepares nanometers by a one-step reaction method at a relatively low temperature (100-140° C.) for the first time. Grade CuCoO ₂ crystal material. Using MOFs material as reactant to introduce Cu or Co source, a fast preparation method of CuCoO ₂ crystal material at low temperature, high yield and low cost was developed, which is helpful for promoting the delafossite structure p-type semiconductor material and its application in the field of optoelectronic devices development is of great academic value.

Compared with the prior art, the beneficial effects of the present invention are:

Nano-scale CuCoO ₂ crystalline materials were prepared by low-temperature hydrothermal method for the first time, which filled the research gap on the synthesis and preparation of delafossite-structured CuCoO ₂ nano-crystalline materials at home and abroad, and is expected to promote p-type ABO ₂ semiconductor materials and their application in the field of optoelectronic devices. application development. It also has the following features:

(1) The method has the advantages of simple preparation process, easy control of process parameters, good experimental repeatability and high single output.

(2) The reaction raw materials used in the method have wide sources, low prices and low production costs.

(3) When the reaction temperature is 100-140 °C, CuCoO ₂ crystal materials can be prepared (as shown in Figure 1). As the reaction temperature decreased from 140°C to 100°C, the nanocrystal size decreased from ∼150 nm (as shown in Fig. 2) to ∼50 nm (as shown in Fig. 3).

(4) XPS was used to test and analyze the valence information of elements on the surface of the CuCoO ₂ crystal material (as shown in Figure 4). The test results show that Cu in the compound is Cu ⁺ , Co is Co ³⁺ , belonging to delafossite (AI ^{B Ⅲ} O ₂ ) Structural materials, consistent with literature reports.

Description of drawings

Fig. 1 is the X-ray diffraction pattern of the reaction products prepared in Examples 1, 2, 3, and 4; the abscissa in the figure is the diffraction angle, and the ordinate is the relative intensity. It can be seen from the figure that when the reaction temperature is 100-140 °C, CuCoO ₂ crystal materials can be prepared, and the corresponding standard diffraction pattern number is #21-0256, which is the main crystal phase of the delafossite structure CuCoO ₂ crystal material. .

2 is a scanning electron microscope image of the CuCoO ₂ crystal material prepared in Example 2. When the reaction temperature was 140°C, the microstructure photos were taken by using field emission scanning electron microscope to observe the reaction product. It can be seen from the figure that the crystal size of the prepared CuCoO ₂ material is about 100-200 nm, and the microscopic morphology conforms to the typical delafossite crystal material.

FIG. 3 is a scanning electron microscope image of the CuCoO ₂ crystal material prepared in Example 4. FIG. When the reaction temperature was 100°C, the microstructure photos were taken by using a field emission scanning electron microscope to observe the reaction products. It can be seen from the figure that the crystal size of the prepared CuCoO ₂ material is about 50-80 nm.

Figure 4 shows the results of X-ray photoelectron spectroscopy (XPS) test and analysis of the CuCoO ₂ crystal material prepared in Example 1, wherein Figure a shows the two characteristic spectral lines of Cu 2p, Cu 2p 3/2 and Cu 2p 1/2 , corresponding to 933.0eV and 952.7eV respectively, which are similar to the Cu 2p spectral lines in other ABO ₂ materials CuAlO ₂ and CuFeO ₂ , indicating Cu ⁺ . In addition, it can be seen from Figure b that the two characteristic spectral lines of Co 2p, Co 2p 3/2 and Co 2p 1/2, correspond to 780.3 eV and 795.4 eV, respectively, which are close to the characteristic spectral lines of Co 2p in Co ₂ O ₃ , indicated as Co ³⁺ .

Detailed ways

The chemical used in the preparation of nano-scale CuCoO ₂ crystal material by hydrothermal reaction in the present invention mainly includes Co(NO ₃ ) ₂ , methanol, 2-methylimidazole, isophthalic acid, Cu(NO ₃ ) ₂ , NaOH, Absolute ethanol, NH ₃ ·H ₂ O and deionized water, etc.

For example, the preparation of Cu-containing MOFs crystal material (Cu-BTC): using the hydrothermal synthesis method, Cu-BTC containing Cu was prepared (the method reported in the existing literature), and after centrifugal cleaning and drying, the Cu-BTC powder can be obtained .

For example, the preparation of Co-containing MOFs crystal material (ZIF-67): use room temperature aging method to prepare Co-containing ZIF-67 (the method reported in the existing literature), and after centrifugal cleaning and drying, ZIF-67 powder can be obtained .

The present invention will be further described below with reference to the embodiments and accompanying drawings, but is not limited to the content described below.

Example 1:

A method for preparing nanoscale delafossite-structured CuCoO ₂ crystal material at low temperature, comprising the following steps:

First prepare the reaction precursor (or hydrothermal reaction precursor): add the Co MOFs crystal material (ZIF-67) and Cu(NO ₃ ) ₂ to the reaction solution in a mass ratio of 1:1 (the reaction solution is deionized water Mixed solution with absolute ethanol, the volume ratio of deionized water and absolute ethanol is 1:2.5), after stirring for 10 to 15 minutes with a magnetic stirrer to dissolve, then add 10 times the mass of ZIF-67 NaOH as a mineralizer, Continue to stir for 10 to 15 minutes until it is completely dissolved to obtain a reaction precursor.

The above-mentioned reaction precursor is transferred to the hydrothermal reactor (generally polytetrafluoroethylene), and the control reaction solution (the reaction solution in the hydrothermal reactor is a mixed solution of deionized water and absolute ethanol, deionized water and absolute ethanol) The volume ratio is 1:2.5), the resistivity of deionized water is 18.24MΩ·cm (25°C), and the filling rate is about 70%. After sealing the kettle body, it was placed in a temperature-controlled oven for hydrothermal reaction, and the reaction temperature was set to 140° C. and the reaction time was 24 hours.

After the reaction, after the kettle body was naturally cooled to room temperature, the kettle body was opened to take out the reaction product (to obtain a precipitate). The reaction product (precipitate obtained) was washed twice by centrifugation with deionized water, dilute NH ₃ ·H ₂ O (mass fraction 1%), deionized water, absolute ethanol, etc., and finally kept in a vacuum oven at 60 °C for 12 hours. After drying, a CuCoO ₂ nanocrystalline material with a size of 100-200 nm can be obtained.

Example 2:

A method for preparing nanoscale delafossite-structured CuCoO ₂ crystal material at low temperature, comprising the following steps:

First prepare the reaction precursor (or hydrothermal reaction precursor): add ZIF-67 and Cu(NO ₃ ) ₂ to the reaction solution in a mass ratio of 1:1.2 (the reaction solution is a mixed solution of deionized water and absolute ethanol) , the volume ratio of deionized water and absolute ethanol is 1:2.5), after the magnetic stirrer is fully stirred for 10 to 15 minutes to dissolve, then add 50 times the mass of ZIF-67 NaOH as a mineralizer, and continue to stir for 10 to 15 minutes. minutes to complete dissolution to obtain a reaction precursor.

The above-mentioned reaction precursor is transferred to the hydrothermal reactor (generally polytetrafluoroethylene), and the control reaction solution (the reaction solution in the hydrothermal reactor is a mixed solution of deionized water and absolute ethanol, deionized water and absolute ethanol) The volume ratio is 1:2.5), the resistivity of deionized water is 18.24MΩ·cm (25°C), and the filling rate is about 75%. After sealing the kettle body, it was placed in a temperature-controlled oven for hydrothermal reaction, and the reaction temperature was set to 140° C. and the reaction time was 24 hours.

After the reaction, after the kettle body was naturally cooled to room temperature, the kettle body was opened to take out the reaction product (to obtain a precipitate). The reaction product (precipitate obtained) was successively cleaned by centrifugation 3 times with deionized water, dilute NH ₃ ·H ₂ O (mass fraction 3%), deionized water, absolute ethanol, etc., and finally kept in a vacuum oven at 60 °C for 8 hours. After drying, a CuCoO ₂ nanocrystalline material with a size of 100-200 nm can be obtained.

Example 3:

A method for preparing nanoscale delafossite-structured CuCoO ₂ crystal material at low temperature, comprising the following steps:

First prepare the reaction precursor (or hydrothermal reaction precursor): add the Co-based MOF material ZIF-67 and Cu(NO ₃ ) ₂ to the reaction solution in a mass ratio of 1:1.2 (the reaction solution is deionized water and anhydrous The mixed solution of ethanol, the volume ratio of deionized water and absolute ethanol is 1:2.5), after the magnetic stirrer is fully stirred for 10 to 15 minutes to dissolve, then add 10 times the mass of Cu(NO ₃ ) ₂ NaOH as a mineralizer , and continue to stir for 10-15 minutes until it is completely dissolved to obtain a reaction precursor.

The above-mentioned reaction precursor is transferred to the hydrothermal reactor (generally polytetrafluoroethylene), and the control reaction solution (the reaction solution in the hydrothermal reactor is a mixed solution of deionized water and absolute ethanol, deionized water and absolute ethanol) The volume ratio is 1:2.5), the resistivity of deionized water is 18.24MΩ·cm (25°C), and the filling rate is about 60%. After sealing the kettle body, it was placed in a temperature-controlled oven for hydrothermal reaction, and the reaction temperature was set to 120° C. and the reaction time was 24 hours.

After the reaction, after the kettle body was naturally cooled to room temperature, the kettle body was opened to take out the reaction product. The reaction product (precipitate obtained) was washed 3 times with deionized water, dilute NH ₃ ·H ₂ O (mass fraction 5%), deionized water, absolute ethanol, etc. in sequence, and finally kept in a vacuum oven at 60 °C for 8 hours. After drying, a CuCoO ₂ nanocrystalline material with a size of 80-200 nm can be obtained.

Example 4:

A method for preparing nanoscale delafossite-structured CuCoO ₂ crystal material at low temperature, comprising the following steps:

First prepare the reaction precursor (or hydrothermal reaction precursor): add ZIF-67 and Cu(NO ₃ ) ₂ into the reaction solution in a mass ratio of 1:1.3 (the reaction solution is a mixed solution of deionized water and absolute ethanol) , the volume ratio of deionized water and absolute ethanol is 1:2.5), after the magnetic stirrer is fully stirred for 10 to 15 minutes to dissolve, then add Cu(NO ₃ ) ₂ 50 times the mass of NaOH as a mineralizer, and continue to stir for 10 ~15 minutes to complete dissolution to obtain the reaction precursor.

The above-mentioned reaction precursor is transferred to the hydrothermal reactor (generally polytetrafluoroethylene), and the control reaction solution (the reaction solution in the hydrothermal reactor is a mixed solution of deionized water and absolute ethanol, deionized water and absolute ethanol) The volume ratio is 1:2.5), the resistivity of deionized water is 18.24MΩ·cm (25°C), and the filling rate is about 75%. After sealing the kettle body, it is placed in a temperature-controlled oven for hydrothermal reaction, and the reaction temperature is set to 100° C. and the reaction time is 24 to 48 hours.

After the reaction, after the kettle body was naturally cooled to room temperature, the kettle body was opened to take out the reaction product. The reaction product (precipitate obtained) was washed 3 times with deionized water, dilute NH ₃ ·H ₂ O (mass fraction 10%), deionized water, absolute ethanol, etc. in sequence, and finally kept in a vacuum oven at 60 °C for 8 hours. After drying, a CuCoO ₂ nanocrystalline material with a size of 50-80 nm can be obtained.

Example 5:

A method for preparing nanoscale delafossite-structured CuCoO ₂ crystal material at low temperature, comprising the following steps:

First prepare the reaction precursor (or hydrothermal reaction precursor): add ZIF-67 and Cu(NO ₃ ) ₂ to the reaction solution in a mass ratio of 1:1.2 (the reaction solution is a mixed solution of deionized water and absolute ethanol) , the volume ratio of deionized water and absolute ethanol is 1:0.4), after stirring with a magnetic stirrer for 10 to 15 minutes to dissolve, then add Cu(NO ₃ ) ₂ 30 times the mass of NaOH as a mineralizer, and continue to stir for 10 to 10 minutes. 15 minutes to complete dissolution to obtain a reaction precursor.

The above-mentioned reaction precursor is transferred to the hydrothermal reactor (generally polytetrafluoroethylene), and the control reaction solution (the reaction solution in the hydrothermal reactor is a mixed solution of deionized water and absolute ethanol, deionized water and absolute ethanol) The volume ratio is 1:0.4), the resistivity of deionized water is 18.24 MΩ·cm (25° C.), and the filling rate is about 75%. After sealing the kettle body, it was placed in a temperature-controlled oven for hydrothermal reaction, and the reaction temperature was set to 100° C. and the reaction time was 48 hours.

After the reaction, after the kettle body was naturally cooled to room temperature, the kettle body was opened to take out the reaction product. The reaction product (precipitate obtained) was successively cleaned by centrifugation for 4 times with deionized water, dilute NH ₃ ·H ₂ O (mass fraction 5%), deionized water, absolute ethanol, etc., and finally kept in a vacuum oven at 60 °C for 12 hours. After drying, CuCoO ₂ nanocrystalline materials can be obtained.

Example 6:

A method for preparing nanoscale delafossite-structured CuCoO ₂ crystal material at low temperature, comprising the following steps:

First prepare the reaction precursor (or hydrothermal reaction precursor): add the MOFs crystal material (Cu-BTC) of Co(NO ₃ ) ₂ and Cu to the reaction solution in a mass ratio of 1:1.2 (the reaction solution is deionized water) Mixed solution with absolute ethanol, the volume ratio of deionized water and absolute ethanol is 1:1), after stirring with a magnetic stirrer for 10 to 15 minutes to dissolve, then add 10 times the mass of Cu-BTC as a mineralizer, Continue to stir for 10 to 15 minutes until it is completely dissolved to obtain a reaction precursor.

The above-mentioned reaction precursor is transferred to the hydrothermal reactor (generally polytetrafluoroethylene), and the control reaction solution (the reaction solution in the hydrothermal reactor is a mixed solution of deionized water and absolute ethanol, deionized water and absolute ethanol) The volume ratio is 1:1), the resistivity of deionized water is 18.24 MΩ·cm (25° C.), and the filling rate is about 70%. After sealing the kettle body, it was placed in a temperature-controlled oven for hydrothermal reaction, and the reaction temperature was set to 140° C. and the reaction time was 24 hours.

After the reaction, after the kettle body was naturally cooled to room temperature, the kettle body was opened to take out the reaction product. The reaction product (precipitate obtained) was successively cleaned by centrifugation for 4 times with deionized water, dilute NH ₃ ·H ₂ O (mass fraction 5%), deionized water, absolute ethanol, etc., and finally kept in a vacuum oven at 60 °C for 12 hours. After drying, CuCoO ₂ nanocrystalline materials can be obtained.

Example 7:

A method for preparing nanoscale delafossite-structured CuCoO ₂ crystal material at low temperature, comprising the following steps:

First prepare the reaction precursor (or hydrothermal reaction precursor): The MOFs crystal material of Co (ZIF-67) and the MOFs crystal material of Cu (Cu-BTC) are added to the reaction solution according to the mass ratio of 1:1.2 (the reaction solution It is a mixed solution of deionized water and absolute ethanol, the volume ratio of deionized water and absolute ethanol is 1:3.0), after stirring for 10-15 minutes with a magnetic stirrer to dissolve, then add 10 times the mass of Cu-BTC as NaOH. The mineralizer is continuously stirred for 10 to 15 minutes until it is completely dissolved to obtain a reaction precursor.

The above-mentioned reaction precursor is transferred to the hydrothermal reactor (generally polytetrafluoroethylene), and the control reaction solution (the reaction solution in the hydrothermal reactor is a mixed solution of deionized water and absolute ethanol, deionized water and absolute ethanol) The volume ratio is 1:3.0), the resistivity of deionized water is 18.24 MΩ·cm (25° C.), and the filling rate is about 70%. After sealing the kettle body, it was placed in a temperature-controlled oven for hydrothermal reaction, and the reaction temperature was set to 140° C. and the reaction time was 24 hours.

After the reaction, after the kettle body was naturally cooled to room temperature, the kettle body was opened to take out the reaction product. The reaction product (precipitate obtained) was sequentially washed four times with deionized water, anhydrous ethanol, etc., and finally dried in a vacuum oven at 60° C. for 12 hours to obtain CuCoO ₂ nanocrystalline material.

Example 8:

The use of the delafossite-structured CuCoO ₂ nanocrystalline materials prepared in the above examples 1-7 mainly refers to the use as electrode materials in optoelectronic functional devices of semiconductor oxides. _{CuCoO 2} particles are prepared on the surface of conductive glass (FTO) by thin film deposition techniques (such as screen printing, thermal spraying decomposition, etc.) Mineral solar cells, etc.) electrode materials. For example, CuCoO ₂ nanocrystals (1.0g), ethyl cellulose (5.0g), terpineol (6.0g), absolute ethanol (30.0g), etc. are added according to the proportion, and the obtained product is obtained by ultrasonic dispersion and rotary evaporation. CuCoO ₂ slurries with different solid contents are then brushed on the surface of conductive glass by screen printing, and after heat treatment and sintering to remove organic substances, CuCoO ₂ electrode film materials are finally obtained.

Example 9:

The use of the delafossite-structured CuCoO ₂ nanocrystalline materials prepared in the above examples 1-7 mainly refers to the use as electrode materials in optoelectronic functional devices of semiconductor oxides. The CuCoO ₂ particles are loaded with CuCoO ₂ nanocrystalline materials on the surface of the working electrode or on the surface of conductive glass (FTO) by thin film deposition techniques (such as drop coating method, thermal spraying decomposition method, etc.), which are used as electrode catalyst materials in photoelectrochemical cells. For example, adding CuCoO ₂ nanocrystals (2.0 g), Nafion (10.0 g), isopropanol (12.0 g), H ₂ O (50.0 g), etc. in proportion to prepare a certain concentration of CuCoO ₂ nanocrystal suspension by ultrasonic dispersion The CuCoO ₂ working electrode material with different loadings can be prepared by adjusting the volume of the suspension, which can be used as a catalyst electrode material in the light/electrolysis water hydrogen evolution and oxygen evolution experiments.

Obviously, those skilled in the art can make various changes and modifications to the hydrothermal preparation method of the delafossite structure CuCoO ₂ nanocrystalline material and the nanocrystalline material of the present invention without departing from the spirit and scope of the present invention. For example, one or more of Cu- or Co-containing MOFs and derivatives thereof are used as reactants, and a Cu source or a Co source is introduced to carry out the hydrothermal reaction. Thus, provided that these modifications and variations of the present invention fall within the technical scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims (6)

1. CuCoO with structure for preparing delafossite at low temperature₂Of nanocrystalline materialsThe method is characterized by comprising the following steps: preparing a reaction precursor by taking MOFs materials as Cu or Co source initial reactants, putting the reaction precursor into a hydrothermal reaction kettle, carrying out hydrothermal reaction for 24-48 hours at 100-140 ℃, carrying out centrifugal cleaning treatment on the reaction product to obtain a precipitate, and drying the precipitate to obtain CuCoO with a delafossite structure₂A crystalline material;

the preparation method of the reaction precursor comprises the following steps: adding a Co source reactant and a Cu source reactant into a mixed solution of deionized water and absolute ethyl alcohol according to the mass ratio of 1: 1-1.3, wherein the volume ratio of the deionized water to the absolute ethyl alcohol is 1: 0.4-3, fully stirring and dissolving in a magnetic stirrer, adding NaOH which is 10-50 times of the mass of the Co source reactant or the Cu source reactant and is used as a mineralizer, and fully stirring until the materials are completely dissolved to obtain a reaction precursor.

2. The low-temperature preparation of delafossite structure CuCoO according to claim 1₂The method for preparing the nanocrystalline material is characterized by comprising the following steps: the Cu source reactant is Cu-containing²⁺Or a MOFs material containing Cu.

3. The low-temperature preparation of delafossite structure CuCoO according to claim 1₂The method for preparing the nanocrystalline material is characterized by comprising the following steps: the Co reactant is Co-containing²⁺Or a Co-containing MOFs material.

4. The low-temperature preparation of delafossite structure CuCoO according to claim 1₂The method for preparing the nanocrystalline material is characterized by comprising the following steps: the centrifugal cleaning treatment method comprises the following steps: according to the sequence of deionized water and dilute NH₃·H₂And O, carrying out centrifugal cleaning on the reaction products by absolute ethyl alcohol in sequence.

5. The low-temperature preparation of delafossite structure CuCoO according to claim 1₂The method for preparing the nanocrystalline material is characterized by comprising the following steps: the centrifugal cleaning treatment method comprises the following steps: according to dilute NH₃·H₂And performing centrifugal cleaning on O, deionized water and absolute ethyl alcohol in sequence.

6. The low-temperature preparation of delafossite structure CuCoO according to claim 1₂The method for preparing the nanocrystalline material is characterized by comprising the following steps: the drying comprises the following steps: and drying the precipitate after the centrifugal cleaning treatment in a vacuum drying oven at 60 ℃ for 4-12 hours.

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