High-performance multifunctional catalyst and application thereof

Abstract

The application belongs to the technical field of electrocatalytic water decomposition, and relates to a high-performance multifunctional catalyst and application thereof. The application is developed around the design and preparation of efficient and stable OER and HER catalysts, and particularly focuses on the modification of NiFe-LDH precursors by using plasma-enhanced atomic layer deposition (PE-ALD) technology to prepare a heterostructure catalyst. This innovative method not only simplifies the preparation process of the catalyst, but also realizes self-reconstruction of the catalyst in the preparation stage, avoids a subsequent complex electrochemical activation process, and greatly improves the preparation efficiency and environmental friendliness.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electrocatalytic water decomposition, and relates to a high-performance multifunctional catalyst and application thereof. BACKGROUND

[0002] Ru / Ir-based noble metal catalysts can accelerate the reaction kinetics and reduce the overpotential of OER. However, the high price and scarcity of these noble metal catalysts limit the widespread commercialization of renewable energy technologies. Therefore, it is urgent to promote the design and development of OER catalysts that are rich in resources, low in cost and excellent in performance to improve the efficiency of renewable energy equipment.

[0003] Transition metal catalysts, including transition metal oxides, sulfides, nitrides and hydroxides, are of great concern due to their low cost, rich resources and inherent OER catalytic activity. The transition metal hydroxyl oxide (TMOOH, TM represents transition metals such as Ni, Fe, Co, etc.) restructured by electrochemical activation is considered to be a real active species. Therefore, researchers have developed many strategies such as doping, leaching and heterostructure engineering to reduce the reconstitution overpotential and improve the OER catalytic activity. Although these methods reduce the reconstitution potential and improve the OER kinetics, multiple cyclic voltammetry (CV) electrochemical activation must be performed to reconstitute and form high-activity TMOOH species. In addition, the reconstitution of the electrode material usually involves a transition from a crystalline state to an amorphous state, which will reduce the conductivity of the material and hinder the transfer of electrons / protons. At the same time, the transition metal active centers will dissolve during long-term operation, resulting in a shortened service life of the electrode. Therefore, directly synthesizing high-activity, high-stability TMOOH species and improving its conductivity at the same time is a feasible method to develop high-performance OER catalysts. SUMMARY

[0004] The purpose of the present application is to solve the problems of slow reconstitution process and poor activity of existing transition metal-based catalysts, and provide a NiFeOOH@TiN-V heterostructure utilizing plasma effect, which is a high-performance multifunctional catalyst that completes self-reconstitution and forms NiFeOOH active centers during the material preparation stage.

[0005] The purpose of the present application can be achieved by the following technical solutions: a high-performance multifunctional catalyst, which is a TiN prepared by plasma-enhanced atomic layer deposition on a NiFe-LDH precursor, wherein the number of cycles of plasma-enhanced atomic layer deposition is 10xN, and N is 1-3.

[0006] In the above-mentioned high-performance multifunctional catalyst, the preparation method of the NiFe-LDH precursor comprises the following steps:

[0007] S1, preparing a NiFe-LDH precursor by mixing a nickel salt, a ferric salt and a hydroxide salt, and stirring to obtain a mixed solution;. 6H2O, FeCl3 . 6H2O and CO(NH2)2 are dissolved in water to form a mixture under uniform stirring;

[0008] S2, the pretreated foamed nickel is added into the mixture to perform high-temperature reaction;

[0009] S3, after cooling, drying treatment is performed to obtain the NiFe-LDH precursor.

[0010] In the above high-performance multifunctional catalyst, in step S1, the molar ratio of NiCl2 . 6H2O, FeCl3 . The molar ratio of 6H2O and CO(NH2)2 is 1:0.1-0.5:5-10.

[0011] In the above high-performance multifunctional catalyst, the pretreatment in step S2 includes the following steps: the foamed nickel is first ultrasonically cleaned in an HCl solution, and then ultrasonically cleaned in a mixture of acetone and ethanol.

[0012] In the above high-performance multifunctional catalyst, the high-temperature reaction temperature in step S2 is 110-125℃, and the time is 12-20h.

[0013] In the above high-performance multifunctional catalyst, the drying treatment in step S3 is performed in a vacuum, the temperature is 50-70℃, and the time is 12-24h.

[0014] In the above high-performance multifunctional catalyst, in the plasma-enhanced atomic layer deposition, tetrakis(dimethylamino)titanium is used as the precursor, and a nitrogen-hydrogen mixed gas is used as the reducing agent, wherein the hydrogen content in the nitrogen-hydrogen mixed gas is 15-25v%.

[0015] Tetrakis(dimethylamino)titanium has good stability at room temperature, which is conducive to its storage and transportation. At the same time, it also has a relatively high vapor pressure, ensuring that it can be effectively evaporated and transported to the reaction chamber during the ALD process, laying the foundation for uniform thin film deposition. Tetrakis(dimethylamino)titanium has very strong reactivity with the nitrogen-hydrogen mixed gas reducing agent, and can react with nitrogen and hydrogen in the carrier gas to form a TiN thin film at a relatively low temperature. This high reactivity ensures the controllability of the thin film growth rate and the efficiency of the deposition process. Due to the high reactivity and good chemical stability of tetrakis(dimethylamino)titanium, using it as a precursor can obtain a dense, uniform and defect-free TiN thin film, which is crucial for maintaining the electrical and mechanical properties of the thin film.

[0016] Under the action of plasma, the nitrogen-hydrogen mixed gas can react with the (dimethylamino) titanium precursor to generate a TiN film. Nitrogen provides nitrogen elements, and hydrogen acts as a reducing agent. The two work together to accelerate the formation of the TiN film. When using nitrogen-hydrogen mixed gas as a reducing agent, it is crucial to control the proportion of hydrogen. Too high hydrogen content will increase the risk of explosion of the system, because hydrogen can easily form an explosive mixture when mixed with air within a certain concentration range.

[0017] In the above-mentioned high-performance multifunctional catalyst, the substrate, tube, chamber and titanium source are heated to 320-380 DEG C, 120-180 DEG C, 130-160 DEG C and 50-80 DEG C respectively during the plasma enhanced atomic layer deposition process.

[0018] In the preparation process of the high-performance multifunctional catalyst, the plasma enhanced atomic layer deposition (PE-ALD) technology is an effective means for precise control of material structure and performance. Especially for the deposition of TiN (titanium nitride) film, temperature is one of the most critical variables in the PE-ALD process. Precise control of the temperature at each stage can ensure the repeatability of the reaction and the high quality of the film. Temperature directly affects the crystallinity, density and adhesion of the film to the substrate, which directly relates to the activity, selectivity and stability of the catalyst.

[0019] In the above-mentioned high-performance multifunctional catalyst, the deposition cycle during the plasma enhanced atomic layer deposition process is set to 0.1-0.5s precursor pulse, 35-45s post-purification, 5-15s gas plasma treatment and 15-25s post-plasma purification.

[0020] The application also provides a use of the high-performance multifunctional catalyst in an electrocatalytic water decomposition reaction.

[0021] Compared with the prior art, the application has the following beneficial effects:

[0022] 1. The application focuses on the design and preparation of efficient and stable OER and HER catalysts, especially the use of plasma enhanced atomic layer deposition (PE-ALD) technology to modify the NiFe-LDH precursor to prepare a heterogeneous structure catalyst. This innovative method not only simplifies the preparation process of the catalyst, but also realizes the self-reconstruction of the catalyst during the preparation stage, avoiding the subsequent complex electrochemical activation process, greatly improving the preparation efficiency and environmental friendliness.

[0023] 2.The catalyst prepared by the present application exhibits excellent OER and HER catalytic activity, as well as outstanding stability. The introduction of the TiN layer not only enhances the electrical conductivity of the catalyst, but also provides additional active sites, significantly reduces the reaction overpotential, and improves the catalytic efficiency. In addition, the TiN layer can effectively protect the active center and prevent it from dissolving during long-term operation, ensuring the long service life of the catalyst.

[0024] 3.The catalyst of the present application can be directly applied to the electrocatalytic water decomposition reaction as a working electrode, efficiently promoting water decomposition to produce hydrogen and oxygen. This not only contributes to the production of hydrogen energy, but also provides a new way for the storage and utilization of clean energy.

[0025] 4.The catalyst of the present application is also suitable for zinc-air batteries as electrode material, which can significantly improve the discharge performance and cycle stability of the battery. This application has important significance for the development of high-energy density, low-cost energy storage systems, and provides the possibility for large-scale storage and utilization of renewable energy. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 X-ray diffraction (XRD) pattern of the NiFeOOH@TiN-V catalyst prepared in Example 1 of the present application;

[0027] Figure 2 Scanning electron microscope (SEM) image of the NiFeOOH@TiN-V catalyst prepared in Example 1 of the present application;

[0028] Figure 3 Transmission electron microscope (TEM) image and energy dispersive spectroscopy (EDS) of the NiFeOOH@TiN-V catalyst prepared in Example 1 of the present application;

[0029] Figure 4 Raman spectrum of the NiFeOOH@TiN-V catalyst prepared in Example 1 of the present application;

[0030] Figure 5 X-ray photoelectron spectroscopy (XPS) spectrum of the NiFeOOH@TiN-V catalyst prepared in Example 1 of the present application;

[0031] Figure 6 X-ray diffraction (XRD) pattern of the NiFe-LDH catalyst prepared in Comparative Example 1 of the present application;

[0032] Figure 7 Scanning electron microscope (SEM) image of the NiFe-LDH catalyst prepared in Comparative Example 1 of the present application;

[0033] Figure 8X-ray photoelectron spectroscopy (XPS) diagram of the NiFe-LDH catalyst prepared for Invention Comparative Example 1;

[0034] Figure 9 Raman diagram of the NiFe-LDH catalyst prepared for Invention Comparative Example 1;

[0035] Figure 10 Raman diagram of the TiN catalyst prepared for Invention Comparative Example 2;

[0036] Figure 11 OER performance test diagram of the catalyst prepared for Invention Example 1 and Invention Comparative Examples 1-2;

[0037] Figure 12 HER performance test of the catalyst prepared for Invention Example 1 and Invention Comparative Examples 1-2;

[0038] Figure 13 OER and HER performance test diagram of the catalyst prepared for Invention Examples 1-3 and Invention Comparative Example 1;

[0039] Figure 14 OER and HER performance diagram of the catalyst prepared for Invention Example 1 and Invention Comparative Examples 1, 3-5;

[0040] Figure 15 OER stability test diagram of the catalyst prepared for Invention Example 1 and Invention Comparative Example 1;

[0041] Figure 16 HER stability test diagram of the catalyst prepared for Invention Example 1 and Invention Comparative Example 1.

[0042] Figure 17 Full hydrolysis performance test diagram of the catalyst prepared for Invention Example 1 and Invention Comparative Example 1. DETAILED DESCRIPTION

[0043] The following are specific embodiments of the present application, which further describe the technical solutions of the present application, but the present application is not limited to these embodiments.

[0044] Example 1:

[0045] S1, clean the commercial foam nickel with a thickness of 1.5 mm in 6M HCl for 20 minutes with an ultrasonic machine to remove surface oxides, and then sequentially clean with acetone and ethanol for 20 minutes.

[0046] S2, under magnetic stirring, add 0.95 mmol NiCl2 . 6H2O, 0.3 mmol FeCl3 .6H2O and 8 mmol CO(NH2)2 were dissolved in 50 mL of deionized water and stirred uniformly for 30 min, and the obtained solution was transferred into a 100 mL Teflon-lined stainless steel autoclave, the cleaned nickel foam was placed in the liner, and kept at 120℃ for 16 h;

[0047] S3, after the reaction, then naturally cooled to room temperature, the nickel foam was taken out and washed repeatedly with deionized water, and finally vacuum dried in a vacuum drying oven at 60℃ for 12 h, and after drying, the NiFe-LDH was obtained;

[0048] S4, the obtained NiFe-LDH sample was deposited with TiN, and by controlling the cycle number to 10×N (N=2), a high-performance multifunctional catalyst NiFeOOH@TiN-V was obtained.

[0049] Figure 1 For the XRD diffraction pattern of the prepared NiFeOOH@TiN-V, only nickel diffraction peaks were observed in the NiFeOOH@TiN-V sample, which may be due to the fact that the TiN nanofilm is too thin to be detected, and the crystallinity of NiFeOOH is poor. The presence of nickel diffraction peaks may be due to the scraping of nickel from the NF substrate.

[0050] Figure 2 For the SEM images of NiFeOOH@TiN-V at different magnifications, it can be seen from the figure that the sample presents a uniform three-dimensional nanowire distribution, which may be the result of the plasma effect in the PE-ALD process.

[0051] Figure 3 a-d are the TEM, HRTEM and diffraction ring of NiFeOOH@TiN-V, which proves the typical nanowire structure, and there are FeOOH, NiOOH and TiN phases, which are consistent with the high-resolution image conclusion. Figure 3 e is the EDS image of NiFeOOH@TiN-V, from which it can be seen that the elements Ni, Fe, Ti, N and O are uniformly distributed. These results confirm that TiN is successfully deposited on the nanowire, and NiFe-LDH is converted into NiFeOOH.

[0052] Figure 4 For the Raman spectrum of NiFeOOH@TiN-V, new Raman peaks of TiN and FeOOH can be observed. The former proves that TiN is successfully deposited on NiFeOOH. The latter indicates that new FeOOH is formed during the PE-ALD process, and FeOOH is a well-known high-activity OER species, and the sample has undergone self-reconstruction again.

[0053] Figure 5The XPS chart of NiFeOOH@TiN-V indicates the formation of high valence Ni and Fe species.

[0054] Example 2:

[0055] The difference from Example 1 is that the number of cycles in step S4 of Example 1 is 10xN (N=3), and a high-performance multifunctional catalyst NiFeOOH@TiN-V-30 can be obtained.

[0056] Example 3:

[0057] The difference from Example 2 is that the number of cycles in step S4 of Example 1 is 10xN (N=3), and a high-performance multifunctional catalyst NiFeOOH@TiN-V-30 can be obtained.

[0058] Comparative Example 1:

[0059] Under magnetic stirring, 1 mmol of NiCl2 . 6H2O, 0.3 mmol of FeCl3 . 6H2O and 8 mmol of CO(NH2)2 were dissolved in 50 mL of deionized water, and after stirring for 30 minutes, the obtained solution was transferred into a 100 mL Teflon-lined stainless steel autoclave, the cleaned foam nickel was placed in the liner, and the foam nickel was kept at 120°C for 16 hours, and then naturally cooled to room temperature. The foam nickel was taken out and repeatedly washed with deionized water, and finally vacuum dried in a vacuum drying box. The final sample obtained is NiFe-LDH.

[0060] Comparative Example 2:

[0061] After the cleaned foam nickel was dried, it was cut into a size of 3*5 cm and directly subjected to step S4.

[0062] Comparative Example 3:

[0063] The sample obtained in Comparative Example 1 was placed in an atomic layer deposition chamber, and the Ti source was not controlled to be turned on, and the remaining parameters were consistent with S4 in Example 1. The sample taken out is NiFe-LDH-P-H.

[0064] Comparative Example 4:

[0065] The sample obtained in Comparative Example 1 was placed in an atomic layer deposition chamber, and the Ti source was not controlled to be turned on, and the remaining parameters were consistent with S4 in Example 1. The sample taken out is NiFe-LDH-P-H.

[0066] The XRD diffraction chart of the prepared NiFe-LDH catalyst is shown in Figure 6 , which proves that the NiFe-LDH sample is successfully synthesized. The SEM chart under different magnifications corresponding thereto is shown in Figure 7As shown, the NiFe-LDH presents an irregular nanowire structure.

[0067] Figure 8 To correspond to its corresponding X-ray photoelectron spectroscopy (XPS) picture, there are peaks of Ni 2p, Fe2p and O1s in the XPS full spectrum, which proves the existence of the above four elements in the NiFe-LDH. In addition, Raman spectroscopy can further confirm the successful synthesis of NiFe-LDH. In the Raman spectrum of Example 1, the Raman peaks at 465 and 535 cm Figure 9 -1 Ⅱ g 1g

[0068] Figure 10 The Raman spectrum of the TiN catalyst prepared in Comparative Example 2 of the present application can be seen in the figure that the vibration peak at 320 cm -1

[0069] The catalysts prepared in Examples 1-3 and Comparative Examples 1-4 were respectively used as working electrodes for electrochemical performance testing. OER and HER performance testing was carried out in 1M KOH. The electrode test was a three-electrode test system, in which a graphite sheet was used as a counter electrode, Hg / HgO was used as a reference electrode, and the prepared electrode was used as a working electrode. Electrochemical measurements were carried out on an electrochemical workstation (Autolab PGSTAT302N, Switzerland).

[0070] Since the electrocatalyst prepared in the present application mainly induces self-reconstruction of the sample surface interface through plasmonic effect, it does not need further electrochemical activation, and high active NiFeOOH is formed to promote its oxygen evolution reaction; the presence of TiN enhances the HER performance of the sample.

[0071] Figure 11 and Figure 12 are respectively the OER and HER performance test figures of the electrocatalyst of Example 1 and Comparative Examples 1-2. As can be seen from the figures, the performance of the NiFeOOH@TiN-V electrode after the deposition of TiN after the plasma effect is more excellent than that of NiFe-LDH and TiN.

[0072] Figure 13 are the OER and HER performance tests of Examples 1-3 and Comparative Example 1, and it can be seen that different cycle numbers have a greater impact on their performance.

[0073] Figure 14 are the OER and HER performance comparisons of Example 1 and Comparative Examples 1-4, and it can be seen that the plasmonic effect is the key to the improvement of the OER performance. ​​​​​​

[0074] Figure 15 and Figure 16 OER and HER stability tests of Example 1 and Comparative Example 1, respectively, can see that the electrode stability is excellent.

[0075] Figure 17 The electrode full-hydrolysis performance test of the catalyst assembly of the application is tested in fresh water and seawater of 1M KOH, respectively, and is stably operated for up to 400 and 250h, indicating its huge practical application potential.

[0076] In summary, the application directly synthesizes a high-activity NiFeOOH species by a plasma-enhanced atomic layer deposition (PE-ALD) technology, and the multifunctional catalyst prepared has excellent catalytic activity and stability, and the preparation process is simple and environmentally friendly.

[0077] The embodiments of the present application do not exhaust the technical scope of the point of the claimed technical range, and the new technical solutions formed by the same or multiple technical features in the technical solutions of the embodiments are also within the scope of the claimed technical range of the present application; at the same time, in all the enumerated or unenumerated embodiments of the present application, the various parameters in the same embodiment only represent one example (i.e. a feasible scheme) of the technical solution, and there is no strict cooperation and limitation relationship between the various parameters, and the various parameters can be replaced with each other without violating the axioms and the claims of the present application, except for the special declaration.

[0078] The technical means disclosed by the present application is not limited to the technical means disclosed by the above technical means, but also includes the technical solutions composed of any combination of the above technical features. The above is the specific implementation of the present application, and it should be pointed out that for ordinary skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements are also considered within the scope of the present application.

[0079] The specific embodiments described herein are merely illustrative of the spirit of the present application. Those skilled in the art can make various modifications or supplements to the described specific embodiments or use similar ways to replace them, without departing from the spirit of the present application or exceeding the scope defined by the appended claims.

Claims

1. A high-performance, multifunctional catalyst, characterized in that, The catalyst is TiN deposited by plasma-enhanced atomic layer deposition on a NiFe-LDH precursor, wherein the number of plasma-enhanced atomic layer deposition cycles is 10×N, and N is 1-3; The method for preparing the NiFe-LDH precursor includes the following steps: S1, NiCl2 . 6H2O, FeCl3 . 6H2O and CO(NH2)2 are dissolved in water and stirred evenly to obtain a mixed solution; S2. Add the pretreated nickel foam to the mixture and react it at high temperature. S3. After cooling, the NiFe-LDH precursor is obtained by drying. The high-temperature reaction in step S2 is carried out at a temperature of 110-125℃ for 12-20 hours. In plasma-enhanced atomic layer deposition, tetrakis(dimethylamino)titanium is used as a precursor, and a nitrogen-hydrogen mixed gas is used as a reducing agent, wherein the hydrogen content in the nitrogen-hydrogen mixed gas is 15-25% v%. During plasma-enhanced atomic layer deposition, the substrate, tube, chamber, and titanium source are heated to 320-380℃, 120-180℃, 130-160℃, and 50-80℃, respectively. The deposition cycle during plasma-enhanced atomic layer deposition is set as follows: 0.1-0.5s precursor pulse, 35-45s precursor purification, 5-15s gas plasma treatment, and 15-25s plasma purification.

2. The high-performance multifunctional catalyst according to claim 1, characterized in that, NiCl2 in step S1 . 6H2O, FeCl3 . The molar ratio of 6H2O to CO(NH2)2 is 1:0.1-0.5:5-10.

3. The high-performance multifunctional catalyst according to claim 1, characterized in that, The pretreatment in step S2 includes the following steps: the nickel foam is first ultrasonically cleaned in HCl solution, and then ultrasonically cleaned in a mixture of acetone and ethanol.

4. The high-performance multifunctional catalyst according to claim 1, characterized in that, Step S3, the drying process, is carried out in a vacuum at a temperature of 50-70℃ for 12-24 hours.

5. The application of a high-performance multifunctional catalyst as described in any one of claims 1-4 in the electrocatalytic water splitting reaction.

Images