NiCo-MOF / Ti3C2Tx-based derivative multi-phase interface compound and application thereof in electro-catalytic hydrogen evolution

Abstract

The invention provides a preparation method of a multiphase interface compound derived based on NiCo-MOF / Ti3C2Tx. The preparation method is specially used for electro-catalytic hydrogen evolution. The metal organic framework is compounded with the Ti < 3 > C < 2 > T < x > MXene, the high specific surface area and adjustable structural characteristics of the MOF are utilized, and the excellent conductivity and interlayer structure advantages of the MXene are combined, so that the composite material disclosed by the invention shows remarkable improvement of electrochemical performance. In the synthesis process, urea is adopted to regulate and control the graphitization degree and morphology, so that the NiCo metal elementary substance is uniformly dispersed on the Ti3C2Tx MXene carrier, and the conductivity and charge transfer capability of the material are further optimized. The prepared NiCo / TiO2-GH composite material shows excellent catalytic performance and good stability in an alkaline medium. Due to the introduction of MXene, not only is a stable carrier provided, but also the conductivity and interlayer ion diffusivity of the catalyst are improved, and the hydrogen evolution efficiency and the material stability are remarkably improved through the synergistic effect of MXene and the functionalized metal center of MOF. The MOF derivation strategy provided by the invention provides a brand new thought for constructing a high-performance electro-catalytic material.

Description

Technical Field

[0001] The present invention relates to a heterogeneous interface composite based on a metal-organic framework (MOF) and MXene composite material, and is particularly applied to the electrocatalytic hydrogen evolution reaction (HER). This technology belongs to the fields of electrochemical catalysts and energy storage, and is specifically used for the preparation of electrocatalysts for water splitting to produce hydrogen. Background Art

[0002] With the increasingly severe environmental pollution and energy crisis, hydrogen energy, as an ideal clean energy, has received extensive attention due to its zero emissions, renewability, and high energy density. Electrocatalytic hydrogen evolution (HER), as one of the important ways to produce hydrogen by water splitting, has become a research hotspot in the energy field. However, existing commercial electrocatalysts mostly rely on noble metal materials (such as Pt / C). Although their catalytic activity is relatively high, their high cost, low stability, and easy deactivation limit their feasibility in large-scale applications. Therefore, developing low-cost, highly efficient, and stable electrocatalysts has become an urgent technical challenge to be solved.

[0003] In recent years, transition metal-based catalysts (such as Ni, Co, Fe, etc.) have become potential substitutes for noble metal catalysts due to their relatively low cost and good catalytic activity. However, the application of transition metal catalysts still faces many problems. Especially during long-term use, problems such as a decrease in catalytic activity, particle agglomeration, and poor stability seriously restrict their practical applications. In addition, although metal-organic frameworks (MOFs) have been widely used in electrocatalytic research due to their large specific surface area, rich pore structure, and adjustable chemical properties, the poor stability of MOFs, especially the problem of structural collapse in high-temperature or strong acidic environments, limits their application in electrocatalytic hydrogen evolution.

[0004] To overcome these problems, in recent years, the combination of MOFs and other highly conductive materials (such as MXenes) has become a promising research direction. As a class of two-dimensional transition metal carbides or nitrides, MXenes have excellent electrical conductivity, high structural stability, and rich surface active sites, and have shown great potential in the fields of electrocatalysis and energy storage. However, when combining MXene with MOF, problems such as poor interfacial compatibility and weak interaction between materials are often faced. This results in that while the composite material of MXene and MOF improves electrical conductivity and stability, it may not effectively exert the synergistic effect of the two, and there are still problems such as insufficient exposure of active sites and unstable interfaces.

[0005] This work aims at the technical defects and barriers existing in current electrocatalytic hydrogen evolution catalysts, and proposes a NiCo-BDC / Ti 3 C 2 T xPrecursor-derived multiphase interface composite NiCo / TiO 2 -G H The preparation method aims to solve the problems of structural stability and active site utilization of MOFs and MXenes composites in practical applications. Specifically, we use NiCo-BDC as the precursor, combined with Ti 3 C 2 T x (MXene material) as the carrier, and regulate the morphology and graphitization degree through urea, and finally obtain NiCo / TiO 2 -G H composite material. This material not only inherits the high specific surface area and adjustable structure of NiCo-BDC MOF, but also significantly enhances the conductivity and stability of the material through the addition of MXene.

[0006] By regulating many derivative conditions of the MOF and MXene composite materials, the present invention successfully overcomes the deficiencies of existing catalysts in terms of stability, conductivity and catalytic activity, and provides an efficient, stable and low-cost electrocatalytic hydrogen evolution catalyst. This technical solution not only provides new ideas for the design of highly efficient electrocatalytic hydrogen evolution materials, but also lays a foundation for the development of next-generation clean energy technologies. Summary of the Invention

[0007] The present invention relates to a NiCo-BDC / Ti-based 3 C 2 T x precursor-derived multiphase interface composite material and its preparation method, aiming to regulate its morphological characteristics and electrochemical performance by regulating the synthesis method of MOF and subsequent derivative strategies, so as to improve its application effect in energy storage and catalytic reactions. The method of the present invention includes compounding NiCo-MOF and MXene and annealing to derive a multiphase interface composite. The Ni and Co elements derived from MOF can be evenly anchored on TiO 2 derived from MXene. The final product inherits the nanosheet structure of the precursor material and has better structural stability than the precursor, and the mutual synergy between the components endows it with excellent catalytic activity.

[0008] The present invention provides a composite material with high stability and excellent electrocatalytic performance, which can effectively overcome the defects of existing catalysts in terms of catalytic activity, stability and conductivity, and solves the technical bottleneck in large-scale applications.

[0009] The technical solution of the present invention is as follows: A multiphase interface composite material is used as an electrocatalytic hydrogen evolution (HER) electrode material. The material is composed of NiCo-BDC / Ti 3 C 2 T xPrepared from a precursor.

[0010] A method for preparing the material, the method comprising the following steps: (1) Add Ti 3 AlC 2 powder into a hydrofluoric acid solution, stir for aluminum layer etching, after the etching is completed, wash, vacuum dry, and then disperse in a suitable solvent, and ultrasonically treat to exfoliate to obtain Ti 3 C 2 T x nanosheets; (2) Disperse the Ti 3 C 2 T x nanosheets obtained in step (1) in N,N-dimethylformamide DMF, and ultrasonically treat to obtain a Ti 3 C 2 T x dispersion; (3) Add CoCl 2 ·6H 2 O and NiCl 2 ·6H 2 O into the Ti 3 C 2 T x dispersion obtained in step (2), and successively add a mixed solvent of DMF, water and absolute ethanol and stir well, then, continue to dissolve urea and terephthalic acid BDC uniformly in the above solution, add nickel foam, and perform a thermal reaction to obtain a NiCo-BDC / Ti 3 C 2 T x precursor material; (4) Place the NiCo-BDC / Ti 3 C 2 T x precursor material obtained in step (3) in a mixed atmosphere for heat treatment for a certain period of time, after the reaction is completed, naturally cool to room temperature, and finally obtain a NiCo-MOF / Ti 3 C 2 T x derived multi-phase interface composite.

[0011] The mass concentration of the hydrofluoric acid solution in step (1) is 35-40%; The aluminum layer etching temperature is 40-80 °C, and the aluminum layer etching time is 1-6 h.

[0012] After the etching is completed, wash the mixture with ethanol and deionized water multiple times until the pH value reaches above 6, such as 6-7.5.

[0013] In some embodiments, the etching temperature of the aluminum layer is 70 °C, and the etching time of the aluminum layer is 2 h.

[0014] The Ti described in step (3) 3 C 2 T x The concentration of the dispersion is 0.5 - 5 mg / mL.

[0015] The Ti in step (2) 3 C 2 T x The optimal concentration of the dispersion is 1 mg / mL -1 .

[0016] The CoCl described in step (3) 2 ·6H 2 O has a molar mass of 0.125 - 0.75 mmol; The NiCl 2 ·6H 2 O has a molar mass of 0.125 - 0.75 mmol.

[0017] The volume ratio of DMF, water, and absolute ethanol described in step (3) is 4 - 12:1 - 2:1 - 2.

[0018] The mass ratio of urea and terephthalic acid described in step (3) is 4:1 - 1:4.

[0019] In the preferred embodiment, the mass ratio of urea and terephthalic acid in step (3) is 1:3.

[0020] The thermal reaction temperature in step (3) is 100 - 160 °C, and the thermal reaction time is 12 - 36 h.

[0021] In the preferred embodiment, the thermal reaction temperature is 140 °C. The reaction time is 48 h.

[0022] The annealing temperature described in step (4) is 300 - 500 °C, the annealing time is 2 - 5 h, and during the annealing process, the heating rate is 1 - 3 °C / min.

[0023] The mixed atmosphere for heat treatment is an argon-hydrogen mixture. In the preferred embodiment, the annealing temperature for heat treatment is 400 °C, the heating rate for heat treatment is 2 °C / min -1 , and the heat preservation time for heat treatment is 3 h.

[0024] In the composite material prepared by adopting the above technical solution of the present invention, NiCo metal simple substances are uniformly dispersed in TiO 2 matrix, and the mass ratio of NiCo metal simple substances is 1:1 - 1:3. The specific surface area of the composite material is greater than 50 m 2 / g porous structure with pore size ranging from 2-10 nm.

[0025] The NiCo-MOF / Ti 3 C 2 T x Application of derived multiphase interface composites as hydrogen evolution catalyst materials.

[0026] Another technical solution of the present invention is to convert NiCo-BDC / Ti 3 C 2 T x The application of the derived multiphase interface composite in electrocatalytic hydrogen evolution (HER). The NiCo-BDC / Ti 3 C 2 T x Derived multiphase interface composites (such as NiCo / TiO 2 -G H After basic characterization of the composite material, the electrocatalytic hydrogen evolution performance was tested. The specific method is as follows: The NiCo / TiO 2 -G H The nickel foam was used as the working electrode, the reference electrode was Ag / AgCl electrode, the counter electrode was a carbon rod, the electrolyte was 1 M KOH, and the NiCo / TiO 2 -G H It has excellent alkaline HER performance.

[0027] The beneficial effects of the present invention are as follows: (1) Excellent composite material control solution The present invention successfully constructs a composite material with a multiphase interface by combining a metal organic framework (MOF) with a MXene material. 3 C 2 T x MXene provides excellent conductivity and structural stability, significantly improving the electrocatalytic hydrogen evolution (HER) performance of the composite material. The NiCo metal element in the composite material is uniformly distributed on the TiO 2 On the matrix, it works synergistically with MXene to effectively improve the catalytic activity and stability.

[0028] (2) Excellent morphology and structural optimization By adding urea to regulate graphitization during the synthesis process, the morphology and structure of the composite material are optimized, and the exposure of catalytic active sites is increased. This regulation method enables the final product to have a larger specific surface area and stronger structural stability, thereby improving the catalytic efficiency and reaction kinetics.

[0029] (3) Significantly improved electrocatalytic performance The NiCo-BDC / Ti prepared by the present invention 3 C 2 T x The derived multiphase interface composite exhibits a low overpotential (177 mV, η = 10 mA cm -2 -2) and an excellent Tafel slope (146 mV dec -1 -1) in 1 M KOH, indicating its high electrocatalytic activity and faster reaction kinetics, significantly improving the efficiency of the electrocatalytic hydrogen evolution reaction.

[0030] (4) Excellent long-term stability After 40 hours of stability testing, the composite material of the present invention maintains its original phase, morphology and catalytic performance, showing strong durability and long-term stability. This indicates that the material can work stably for a long time in practical applications, avoiding common catalyst deactivation and performance degradation problems.

[0031] (5) Low cost and high performance The composite material of the present invention ensures both low cost and high catalytic performance through the synergistic effect of MOF and MXene. The material can achieve efficient hydrogen evolution at a low overpotential, overcoming the high cost problem of traditional noble metal catalysts and having good commercial application potential.

[0032] (6) Wide application prospects The composite material of the present invention is not only applicable to electrocatalytic hydrogen evolution, but also can be widely applied to other electrochemical reactions, energy storage fields such as supercapacitors, showing high application prospects and economic value, and having broad market potential. Brief description of the drawings

[0033] Figure 1 XRD comparison schematic diagram of NiCo / TiO 2 -G H synthesized in Example 1 with different heat treatment times.

[0034] Figure 2 Scanning electron microscope image of NiCo / TiO 2 -G H synthesized in Example 1.

[0035] Figure 3 Transmission electron microscope image of NiCo / TiO 2 -G H synthesized in Example 1.

[0036] Figure 4LSV comparison diagrams for Example 1, Example 2, Example 3, Example 4, Example 5, and Example 6. Specific implementation The present invention will be further described below in conjunction with embodiments, but the scope of protection required by the present invention is not limited to the scope described in the embodiments.

[0038] Example 1: NiCo / TiO 2 -G H Preparation of composite material Put 200 mg of Ti 3 AlC 2 in hydrofluoric acid with a mass concentration of 40% and stir-etch at 70 °C for 2 h to remove the aluminum layer. After the etching is completed, wash the Ti 3 C 2 T x with ethanol and deionized water until the pH is 6.5. Disperse the Ti 3 C 2 T x nanosheets in N,N-dimethylformamide (DMF), and ultrasonically treat for 8 hours to obtain a Ti 3 C 2 T x dispersion with a concentration of 1 mg / mL. Add CoCl 2 ·6H 2 O (89.2 mg) and NiCl 2 ·6H 2 O (89.1 mg), as well as 12 mL of DMF, 2 mL of deionized water, and 2 mL of absolute ethanol, and stir well. Then add 21 mg of urea and 62.3 mg of terephthalic acid (BDC), and continue to stir evenly. Transfer the solution to a polytetrafluoroethylene-lined container, react at 140 °C for 48 hours, naturally cool to room temperature after the reaction, wash with deionized water and absolute ethanol until there is no residue, and finally dry in vacuum at 60 °C to obtain the NiCo-BDC / Ti 3 C 2 T x precursor material. Place the NiCo-BDC / Ti 3 C 2 T x precursor material in an argon-hydrogen mixed atmosphere, anneal at 400 °C with a heating rate of 2 °C / min, and hold for 3 hours. After the reaction is completed, naturally cool to room temperature. Finally, obtain the NiCo / TiO 2 -G H composite material.

[0039] For the above Example 1, cases of heat treatment for 0 hours (i.e., no annealing), 1 h annealing, and 3 h annealing were also carried out. From Figure 1Among them, the diffraction patterns of samples with different heat treatment times show that Ni-MOF is first reduced to elemental nickel, while Co-MOF needs to undergo the transformation process of Co-MOF-CoO-Co, and the oxidation of Ti 3 C 2 T x also proceeds step by step with the heat treatment time.

[0040] Figure 3 In the sample NiCo / TiO 2 -G H added with urea during the synthesis process exhibits a layered morphology beneficial to the electrochemical reaction, and the nanosheet structure composed of numerous nanoparticles is particularly prominent. Since both MXene and BDC are two-dimensional layered materials, after heat treatment and decomposition, the target product is oxidized / reduced into nanoparticles while retaining the precursor structure, thus significantly increasing the specific surface area and electrochemical active sites of the product, which has a positive effect on the electrocatalytic process. The results show that the introduction of urea can effectively inhibit the mutual stacking between nanosheets and help the composite material maintain its original layered structure.

[0041] Example 2: Preparation of NiCo / TiO 2 -G L Composite material Without adding urea and with other experimental conditions the same as in Experimental Example 1, NiCo / TiO 2 -G L can be obtained.

[0042] Example 3: Preparation of Ni / TiO 2 -G H Composite material Without adding cobalt salt CoCl 2 ·6H 2 O and with other experimental conditions the same as in Experimental Example 1, Ni / TiO 2 -G H can be obtained.

[0043] Example 4: Preparation of Ni / TiO 2 -G L Composite material Without adding cobalt salt CoCl 2 ·6H 2 O and urea and with other experimental conditions the same as in Experimental Example 1, Ni / TiO 2 -G L can be obtained.

[0044] Example 5: Preparation of Co / TiO 2 -G H Composite material Without adding nickel salt NiCl 2 ·6H2 O, with other experimental conditions the same as in Experimental Example 1, Co / TiO 2 -G H .

[0045] Example 6: Preparation of Ni / TiO 2 -G L Composite material Without adding cobalt salt CoCl 2 ·6H 2 O and urea, with other experimental conditions the same as in Experimental Example 1, Ni / TiO 2 -G L .

[0046] Figure 4 The effect diagrams of different composite materials obtained in Examples 1-6 are given. Among the samples without morphology regulation, for NiCo / TiO 2 -G L at η = 10 mA cm -2 the overpotential is 219 mV, which is better than 305 mV of Ni / TiO 2 -G L and 290 mV of Co / TiO 2 -G L . After morphology regulation, the hydrogen evolution performance of the samples shows the same trend. For NiCo / TiO 2 -G H the overpotential is 177 mV, significantly better than 283 mV of Ni / TiO 2 -G H and 210 mV of Co / TiO 2 -G H . It should be noted that the regulated electrode materials all show a certain performance improvement compared with the unregulated samples. This phenomenon can be attributed to the fact that morphology regulation can effectively expose more electrochemically active sites, increase the effective area participating in the electrochemical reaction, and thus improve the overall performance.

[0047] Example 7: Preparation of NiCo / TiO 2 -G L -300 composite material Change the annealing temperature to 300 °C, with other experimental conditions the same as in Experimental Example 1, NiCo / TiO 2 -G L -300 can be obtained. In Example 7, the overpotential corresponding to 10 mA cm -2 is η = 273 mV, and the Tafel slope is 185 mV dec -1 .

[0048] Example 8: NiCo / TiO2 -G L Preparation of -350 composite material Change the annealing temperature to 300 °C, and other experimental conditions are the same as in Experimental Example 1, then NiCo / TiO can be obtained 2 -G L -350. In Example 8, the overpotential corresponding to 10 mA cm -2 is η = 240 mV, and the Tafel slope is 200 mV dec -1 .

[0049] Example 9: Preparation of NiCo / TiO 2 -G L -450 composite material Change the annealing temperature to 300 °C, and other experimental conditions are the same as in Experimental Example 1, then NiCo / TiO can be obtained 2 -G L -450. In Example 9, the overpotential corresponding to 10 mA cm -2 is η = 230 mV, and the Tafel slope is 180 mV dec -1 .

[0050] Example 10: Preparation of NiCo-G L -400 Without adding Ti 3 C 2 T x MXene, and other experimental conditions are the same as in Experimental Example 1, then NiCo -G L -400 can be obtained. In Example 10, the overpotential corresponding to 10 mA cm -2 is η = 271 mV, and the Tafel slope is 189 mV dec -1 .

[0051] The present invention provides a novel catalyst preparation strategy, aiming to optimize the electrocatalytic hydrogen evolution (HER) performance by regulating the composite mode of metal-organic framework (MOF) and MXene materials. First, a solvothermal method is used to synthesize Ti 3 C 2 T x / NiCo-BDC precursor material, and through heat treatment in an argon-hydrogen mixed atmosphere, it is converted into NiCo / TiO with a multiphase interface 2 -G HComposite material. This strategy realizes precise control over the morphology and graphitization degree of the target product by introducing urea during the synthesis process, thereby improving the structural stability and electrochemical performance of the material. Specifically, the addition of urea effectively regulates the graphitization degree of the composite material and optimizes its morphological characteristics, thus promoting the synergistic effect among the components. This strategy not only improves the stability of the catalyst but also optimizes the efficiency of the hydrogen evolution reaction in water electrolysis.

[0052] The core innovation of the present invention lies in achieving a significant improvement in material performance through precise control of the composite mode of MOF and MXene, especially through the graphitization and morphology optimization strategy regulated by urea. This technology provides a new design idea for MOFs / MXenes-derived materials and has broad application potential, especially in the fields of electrocatalysis and other electrochemical reactions.

[0053] The above embodiments are only the preferred technical solutions of the present invention and should not be regarded as limitations on the present invention. The embodiments in this application and the features in the embodiments can be arbitrarily combined with each other without conflict. The protection scope of the present invention should be the technical solutions recorded in the claims, including the equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, the equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A novel method based on NiCo-MOF / Ti3C2T x A method for preparing a derivative multiphase interface composite, characterized in that: The synthesis method comprises the following steps: (1) Ti3AlC2 powder is added to a hydrofluoric acid solution and stirred to etch the aluminum layer. After etching, it is washed and vacuum dried, dispersed in an appropriate solvent, and ultrasonically peeled to obtain Ti3C2T x Nanosheets; (2) Ti3C2T prepared in step (1) x The nanosheets were dispersed in N,N-dimethylformamide (DMF) and ultrasonicated to obtain Ti3C2T x Dispersion liquid; (3) Add CoCl2·6H2O and NiCl2·6H2O to the Ti3C2T x The mixed solvent of DMF, water and anhydrous ethanol is added to the dispersion in sequence and stirred thoroughly. Then, urea and terephthalic acid BDC are uniformly dissolved in the above solution, and nickel foam is added to obtain NiCo-BDC / Ti3C2T after thermal reaction. x Precursor materials; (4) NiCo-BDC / Ti3C2T obtained in step (3) x The precursor material was placed in a mixed atmosphere for a certain period of heat treatment. After the reaction was completed, it was naturally cooled to room temperature to finally obtain a NiCo-MOF / Ti3C2T x Derivatization of multiphase interface composites.

2. The NiCo-MOF / Ti3C2T based on claim 1 x A method for preparing a derivative multiphase interface composite, characterized in that: The mass concentration of the hydrofluoric acid solution in step (1) is 35-40%; The etching temperature of the aluminum layer is 40-80°C, and the etching time of the aluminum layer is 1-6 h.

3. The NiCo-MOF / Ti3C2T based on claim 1 x A method for preparing a derivative multiphase interface composite, characterized in that: Ti3C2T in step (3) x The dispersion concentration is 0.5-5 mg / mL.

4. The NiCo-MOF / Ti3C2T based on claim 1 x A method for preparing a derivative multiphase interface composite, characterized in that: The molar mass of the CoCl2·6H2O in step (3) is 0.125-0.75 mmol; the molar mass of the NiCl2·6H2O is 0.125-0.75 mmol.

5. The NiCo-MOF / Ti3C2T based on claim 1 x A method for preparing a derivative multiphase interface composite, characterized in that: The volume ratio of DMF, water and anhydrous ethanol in step (3) is 4-12:1-2:1-2.

6. The NiCo-MOF / Ti3C2T based on claim 1 x A method for preparing a derivative multiphase interface composite, characterized in that: The mass ratio of urea to terephthalic acid in step (3) is 4:1-1:

4.

7. The NiCo-MOF / Ti3C2T based on claim 1 x A method for preparing a derivative multiphase interface composite, characterized in that: The heating temperature of step (3) is 100-160°C, and the thermal reaction time is 12-36 h.

8. The NiCo-MOF / Ti3C2T based on claim 1 x A method for preparing a derivative multiphase interface composite, characterized in that: The annealing temperature in step (4) is 300-500°C, and the annealing time is 2-5 h.

9. The NiCo-MOF / Ti3C2T based on claims 1-8 x A method for preparing a derivative multiphase interface composite, characterized in that: In the prepared composite material, the NiCo metal element is uniformly dispersed in the TiO2 matrix, and the mass ratio of the NiCo metal element is 1:1-1:

3. The composite material has a specific surface area greater than 50 m 2 / g porous structure with pore size ranging from 2-10 nm.

10. The NiCo-MOF / Ti3C2T3O3 prepared according to the method described in any one of claims 1 to 9 x Application of derived multiphase interface composites as hydrogen evolution catalyst materials.

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