Two-dimensional titanium carbide supported iron selenide composite electrode catalyst and its preparation method

Abstract

The present invention discloses a two-dimensional titanium carbide supported iron selenide composite electrode catalyst and a preparation method thereof. The preparation method includes: dissolving titanium carbide nanosheets in N,N-dimethylformamide, performing ultrasonic treatment to obtain a two-dimensional titanium carbide nanosheet suspension; adding hydrazine hydrate and selenium powder to the two-dimensional titanium carbide nanosheet suspension, and performing mixing and stirring; adding Fe(NO3)3·9H2O and polyvinylpyrrolidone to the stirred mixture for reaction; performing a solvothermal reaction on the composite product obtained after the reaction at a high temperature; after the solvothermal reaction, performing centrifugation and washing with water to collect the product, removing the supernatant, and freeze-drying to obtain the two-dimensional titanium carbide supported iron selenide composite electrode catalyst. The present invention optimizes the composite structure of the catalyst, which is beneficial to the contact between the electrolyte and the components of the catalyst, promotes electron transfer in the catalytic reaction, and exhibits good cycle stability and electrocatalytic activity.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparation of electrode catalysts, and relates to a two-dimensional titanium carbide supported iron selenide composite electrode catalyst and a preparation method thereof. Background Art

[0002] Facing the depletion of fossil fuels and environmental pollution, the clean and efficient utilization of traditional fossil energy and the large-scale development of sustainable energy have become the top priorities. Among the alternative renewable energies, hydrogen (H2) has attracted much attention to meet the growing energy demand due to its high combustion value, diverse usage forms, and rich reserves. Currently, the most effective method for clean hydrogen production is generally considered to be the electrochemical water splitting based on noble metal electrode materials. Among them, platinum (Pt) is widely regarded as the best single-metal catalyst for the hydrogen evolution reaction (HER). However, the scarcity and high cost of noble metals have severely hindered their large-scale commercial applications. In this context, promoting the development of efficient and noble-metal-free HER electrocatalysts has become a research hotspot.

[0003] In recent years, binary selenium compounds (such as FeSe x , MoSe2, WSe2, etc.) are expected to replace Pt electrocatalysts due to their low price, good electrocatalytic effect, etc. In particular, FeSe2 is considered to be an efficient hydrogen evolution electrocatalyst because of its natural abundance, additional catalytic electron structure, and good electrocatalytic ability. However, compared with Pt-based electrocatalysts, pure FeSe2 usually lacks sufficient edge sites and has low electrical conductivity, resulting in a decrease in electrocatalytic efficiency and thus a low charge transfer rate in the catalytic system. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a two-dimensional titanium carbide supported iron selenide composite electrode catalyst and a preparation method thereof. The electrode catalyst has high electrical conductivity and improves the catalytic efficiency of the hydrogen evolution reaction.

[0005] To achieve the above purpose, the present invention is implemented by the following technical solutions:

[0006] A preparation method of a two-dimensional titanium carbide supported iron selenide composite electrode catalyst includes the following steps:

[0007] Dissolve titanium carbide nanosheets in N, N-dimethylformamide, and perform ultrasonic treatment to obtain a two-dimensional titanium carbide nanosheet suspension;

[0008] Add hydrazine hydrate and selenium powder to the two-dimensional titanium carbide nanosheet suspension, and perform mixing and stirring;

[0009] Add Fe(NO3)3·9H2O and polyvinylpyrrolidone to the stirred mixture for reaction;

[0010] The composite product obtained after the reaction is subjected to a solvothermal reaction at a high temperature;

[0011] After the solvothermal reaction, centrifugation and water washing are carried out to collect the product, the supernatant is removed, and freeze-drying is carried out to obtain a two-dimensional titanium carbide supported iron selenide composite electrode catalyst.

[0012] Optionally, the mass ratio of titanium carbide nanosheets to the volume of N, N-dimethylformamide is 2:5.

[0013] Optionally, the mass ratio of titanium carbide nanosheets to selenium powder is 500:237.

[0014] Optionally, the volume ratio of N, N-dimethylformamide to hydrazine hydrate is 625:6.

[0015] Optionally, the mass ratio of titanium carbide nanosheets to polyvinylpyrrolidone is 20:13.

[0016] Optionally, the mass ratio of titanium carbide nanosheets to Fe(NO3)3·9H2O is 250:303.

[0017] Optionally, the temperature of the solvothermal reaction is 180 °C and the time is 12 h; the temperature during freeze-drying is -180 °C and the drying pressure is 1000 Pa.

[0018] Optionally, the preparation method of titanium carbide nanosheets includes:

[0019] Adding LiF powder to the HCl solution and stirring;

[0020] Slowly adding Ti3AlC2 powder to the stirred solution and stirring for an etching reaction;

[0021] Centrifuging the product after the etching reaction, adding deionized water to the centrifuged precipitate and stirring until the pH is greater than 6 to obtain a Ti3C2Tx suspension;

[0022] Under the protection of an inert gas, the Ti3C2Tx suspension is ultrasonically treated, and after ultrasonic treatment, centrifugation and vacuum drying are carried out to obtain titanium carbide nanosheets.

[0023] Optionally, the mass ratio of LiF powder to Ti3AlC2 powder is 1:1.

[0024] A two-dimensional titanium carbide supported iron selenide composite electrode catalyst is prepared by the above preparation method.

[0025] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0026] A two-dimensional titanium carbide supported iron selenide composite electrode catalyst provided by the present invention is a battery device with a high current density and long lifespan.

[0027] FeSe2 nanocrystals can be embedded into the Ti3C2T x interlayer. This uniform growth effectively prevents the stacking between Ti3C2T x nanolayers, thereby enhancing the effective active sites of the electrode catalyst. The excellent composite structure is also conducive to improving the electron transfer rate. The introduction of a large number of FeSe2 nanocrystals, combined with the intrinsically high conductivity of FeSe2 in the composite material, reflects the synergistic effect of multiple materials and is beneficial to the improvement of the catalytic efficiency.

[0028] The preparation method of a two-dimensional titanium carbide supported iron selenide composite electrode catalyst of the present invention is simple, has excellent performance, uses abundant and inexpensive raw materials, has high utilization value, and is conducive to large-scale industrial production. Description of the Drawings

[0029] Figure 1 It is a process schematic diagram of the present invention;

[0030] Figure 2 It is the XPS spectra (a); C element spectrum (b), Ti element spectrum (c), Se element spectrum (d), Fe element spectrum (e) of the two-dimensional titanium carbide supported iron selenide composite electrode catalyst prepared in Example 1 of the present invention;

[0031] Figure 3 It is the field emission scanning electron microscope (FE-SEM) images (a-c) of the two-dimensional titanium carbide supported iron selenide composite electrode catalyst prepared in Example 1 of the present invention;

[0032] Figure 4 It is the transmission electron microscope (TEM) photograph of the two-dimensional titanium carbide supported iron selenide composite electrode catalyst prepared in Example 1 of the present invention;

[0033] Figure 5 It is the linear sweep voltammetry (Figure a) and (Figure b) Tafel slope comparison curves of the two-dimensional titanium carbide supported iron selenide composite electrode catalyst (FeSe2 / Ti3C2T x ) prepared in Example 1 of the present invention for the electrocatalytic hydrogen production reaction compared with the iron selenide electrode catalyst (FeSe2) and the titanium carbide electrode catalyst ((Ti3C2T x ));

[0034] Figure 6 It is the linear voltammetric cycling test graph of the two-dimensional titanium carbide supported iron selenide composite electrode catalyst (FeSe2 / Ti3C2T x ) prepared in Example 1 of the present invention. Detailed implementation manners

[0035] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention, and cannot be used to limit the protection scope of the present invention.

[0036] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0037] For the purposes of this specification and the appended claims, unless otherwise stated, all numbers expressing amounts, percentages or proportions and other numerical values used in this specification and the appended claims are understood to be modified by the term "about" in all cases. In addition, all ranges disclosed herein include the endpoints and can be combined independently.

[0038] Embodiment 1

[0039] As Figures 1 to 6 shown, a preparation method of a two-dimensional titanium carbide supported iron selenide composite electrode catalyst includes the following steps:

[0040] S1. Add 1 g of LiF powder to 20 mL of 9 M HCl solution and magnetically stir for 0.5 h;

[0041] S2. Slowly add 1 g of Ti3AlC2 powder to the solution after stirring in S1, and magnetically stir for 36 h at 35 °C for an etching reaction;

[0042] S3. Centrifuge the product after the etching reaction, add deionized water to the centrifuged precipitate and stir repeatedly until the pH is greater than 6 to obtain a Ti3C2Tx suspension;

[0043] S4. Under the protection of argon gas, ultrasonically treat the Ti3C2Tx suspension for 0.5 h, centrifuge at 3500 rpm for 1 h, and vacuum dry to obtain titanium carbide nanosheets;

[0044] S5. Dissolve 20 mg of titanium carbide nanosheets in 50 ml of N, N-dimethylformamide, and perform ultrasonic treatment until a uniformly dispersed solution is obtained, that is, a two-dimensional titanium carbide nanosheet suspension;

[0045] S6. Add 0.48 ml of hydrazine hydrate and 9.48 mg of selenium powder to the two-dimensional titanium carbide nanosheet suspension, and magnetically stir for 75 min to mix evenly;

[0046] S7, Add 24.24 mg of Fe(NO3)3·9H2O and 13 mg of polyvinylpyrrolidone to the mixed solution after stirring in S6, and react at room temperature for 20 min;

[0047] S8, Transfer the composite product obtained after the reaction in S7 to a stainless steel autoclave with a Telfon liner for solvothermal reaction. The temperature of the solvothermal reaction is 180 °C and the time is 12 h;

[0048] S9, After the solvothermal reaction, perform centrifugation and wash with deionized water 3 times, with each washing time being 8 min. Collect the product, remove the supernatant, and freeze-dry to maintain its composite structure. The temperature during freeze-drying is -180 °C and the drying pressure is 1000 Pa to obtain a two-dimensional titanium carbide supported iron selenide composite electrode catalyst.

[0049] Example Two

[0050] As Figures 1 to 6 shown, based on the preparation method of a two-dimensional titanium carbide supported iron selenide composite electrode catalyst described in Example One, this example provides a two-dimensional titanium carbide supported iron selenide composite electrode catalyst, which is prepared by the above preparation method.

[0051] Comparative Example One

[0052] A preparation method of an iron selenide electrode catalyst includes the following steps:

[0053] S1, Add 0.48 mL of hydrazine hydrate and 9.48 mg of selenium powder to 50 ml of N, N-dimethylformamide, and stir magnetically to mix evenly;

[0054] S2, Mix 24.24 mg of Fe(NO3)3·9H2O and 13 mg of polyvinylpyrrolidone into the mixed solution after stirring in S1, and react at room temperature for 20 min;

[0055] S3, Transfer the mixture solution after the reaction in S2 to a stainless steel autoclave with a Telfon liner for solvothermal reaction. The temperature of the solvothermal reaction is 180 °C and the time is 12 h;

[0056] S4, After the solvothermal reaction, perform centrifugation and washing with water, remove the supernatant, and freeze-dry to maintain its composite structure, and finally obtain an FeSe2 electrode catalyst.

[0057] Comparative Example Two

[0058] A preparation method of a two-dimensional titanium carbide electrode catalyst includes the following steps:

[0059] S1. Add 1 g of LiF powder into 20 mL of 9 M HCl solution and stir magnetically for 0.5 h.

[0060] S2. Slowly add 1 g of Ti3AlC2 powder into the solution after stirring in S1, and carry out an etching reaction by magnetic stirring at 35 °C for 36 h.

[0061] S3. Centrifuge the product after the etching reaction, add deionized water to the centrifuged precipitate and stir repeatedly until the pH is greater than 6 to obtain a Ti3C2Tx suspension.

[0062] S4. Under the protection of argon gas, ultrasonically treat the Ti3C2Tx suspension for 0.5 h, centrifuge at 3500 rpm for 1 h, and vacuum dry to obtain titanium carbide nanosheets.

[0063] S5. Dissolve 20 mg of titanium carbide nanosheets in 50 ml of N, N-dimethylformamide, and carry out ultrasonic treatment until a uniformly dispersed solution is obtained, namely a two-dimensional titanium carbide nanosheet suspension.

[0064] Taking the two-dimensional titanium carbide supported iron selenide composite electrode catalyst prepared by the method of Example 1 as an example for performance characterization.

[0065] As Figure 2 shown, the XPS spectrum reveals that the FeSe2 / Ti3C2T x structure mainly contains five elements: Ti, C, O, Fe and Se. Among them, the C1s fine spectrum shows that the C element in the composite structure is mainly composed of four different chemical bonds, namely C-Ti-T x , C-C, CH x / C-O and C=O, which correspond to the combined peaks at 281.0, 284.2, 285.8 and 287.8 eV ( Figure 2 b). The N1s spectrum consists of three peaks, namely sp 2 c=N with a lower binding energy, N-(C)3 with an energy of 399 eV and amino N with an energy of 400.6 eV. In addition, the Se 3d and Fe 2p fine spectra also show the binding peaks of different orbital valence states, among which Se 3 d 5 / 2 and Se 3 d 3 / 2 signals are located at 55.3 and 59.8 eV, and the 2 2+ of Fe p 2 / 3 and 2 p 1 / 3The signals are located at 711.7 (S1) and 725.3 eV (S’1), and those at 714.1 (S2) and 724.3 eV (S’2) are the binding peaks of Fe. 3+ The binding peaks.

[0066] As Figure 3 shown, the Ti3C2T x hybrid has a two-dimensional layered structure. This image indicates that the two-dimensional Ti3C2T x nanosheets are well exfoliated and have a suitable surface area, which provides many exposed active edges for the loading of FeSe2 nanocrystals. The FeSe2 nanocrystals are confined to grow on the surface of Ti3C2T x effectively preventing the stacking between the layers of Ti3C2T x nanosheets.

[0067] As Figure 4 shown, it is further confirmed that the well-dispersed FeSe2 nanocrystals distributed on the surface of Ti3C2T x have abundant edge sites, which are expected to provide sufficient catalytic active sites for HER. The typical lattice spacing of the FeSe2 nanocrystals and Ti3C2T x nanosheets also indicates the successful loading of the FeSe2 nanocrystals. It also corroborates that an effective interconnection is formed between the FeSe2 nanocrystals and Ti3C2T x nanosheets, avoiding the stacking and aggregation of two-dimensional nanomaterials and constructing a novel two-dimensional composite electrode catalyst.

[0068] The catalytic activity of the prepared catalyst samples was tested as follows:

[0069] The electrochemical tests of the samples were all carried out on a CHI760E electrochemical workstation. The test system was a standard three-electrode system, in which a Pt wire was used as the counter electrode, a saturated calomel electrode was used as the reference electrode, and a glassy carbon electrode with a diameter of 3 mm coated with the two-dimensional composite catalytic material was used as the working electrode. The preparation process of the working electrode was as follows: Weigh 2 mg of the two-dimensional composite catalytic material and disperse it in a mixed solution (475 μL of deionized water, 475 μL of ethanol, and 50 μL of 5% Nafion 117), and ultrasonically treat it for 30 min. Drop 5 μL of the above catalyst sample on the surface of the pretreated glassy carbon electrode and dry it at room temperature before testing. The catalytic activity and cyclic stability of the catalyst for the electrocatalytic hydrogen production reaction were measured by linear sweep voltammetry. The hydrogen precipitation performance was tested in a 0.5 M H2SO4 aqueous solution, and the polarization curve was collected at a potential sweep rate of 2 mV s -1 The potential sweep rate was 10 mV s at a potential of -0.258~-0.338 V (VS RHE) at room temperature for 3000 cycles.-1 The hydrogen precipitation performance was tested in a 0.5 M H2SO4 aqueous solution, and polarization curves were collected at a potential scanning rate of 2 mV s -1 . The durability test was carried out in 0.5 M H2SO4, and 3000 cycles were performed at 10 mV s -1 (VS RHE), and the current-PME response was monitored for 4000 s using chronoamperometry technique.

[0070] As can be seen from Figure 5 a, the two-dimensional titanium carbide supported iron selenide composite electrode catalyst has the lowest initial potential and the highest current density for the reaction, indicating good catalytic durability; as can be seen from Figure 5 a, the two-dimensional titanium carbide supported iron selenide composite electrode catalyst has the smallest Tafel slope, indicating the best catalytic activity of the catalyst. At the same time, as Figure 6 shown, after 3000 cycle tests, the activity of the catalyst hardly decays, indicating its excellent cycle stability.

[0071] In addition, the hydrogen production catalytic activity of the electrode catalysts prepared by the methods of Example 1 and Comparative Examples 1 and 2 was detected, and the results are shown in Table 1.

[0072] Table 1 Performance indexes of the catalysts prepared in Example 1 and Comparative Examples 1 and 2 for hydrogen production reaction

[0073]

[0074] As can be seen from Table 1, the catalysts prepared by the method of Example 1 all have low overpotential, low Tafel slope and large exchange current density, and high catalytic activity. Compared with Example 1, the Tafel slopes of the iron selenide electrode catalyst in Comparative Example 1 and the titanium carbide nanoelectrode catalyst in Comparative Example 2 are high, and the performance of the catalysts is low. The composite of iron selenide and titanium carbide in a certain proportion is beneficial to comprehensively exert the catalytic performance of the two, produce a synergistic effect, and improve the catalytic activity and catalytic stability of the sample

[0075] The above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and deformations can be made, and these improvements and deformations should also be regarded as the protection scope of the present invention.

Claims

1. A preparation method of a two-dimensional titanium carbide supported iron selenide composite electrode catalyst, characterized in that, The steps include: Dissolve titanium carbide nanosheets in N, N-dimethylformamide and perform ultrasonic treatment to obtain a two-dimensional titanium carbide nanosheet suspension; Add hydrazine hydrate and selenium powder to the two-dimensional titanium carbide nanosheet suspension and perform mixing and stirring; Add Fe(NO3)3·9H2O and polyvinylpyrrolidone to the stirred mixture for reaction; Perform solvothermal reaction on the composite product obtained after the reaction at 180 °C; After the solvothermal reaction, perform centrifugation, washing with water to collect the product, remove the supernatant, and freeze-dry to obtain a two-dimensional titanium carbide-supported iron selenide composite electrode catalyst; The preparation method of titanium carbide nanosheets includes: Add LiF powder to the HCl solution and stir; Slowly add Ti3AlC2 powder to the stirred solution and stir for an etching reaction; Centrifuge the product after the etching reaction, add deionized water to the centrifuged precipitate and stir until the pH is greater than 6 to obtain a Ti3C2Tx suspension; Under the protection of inert gas, perform ultrasonic treatment on the Ti3C2Tx suspension, and after ultrasonic treatment, perform centrifugation and vacuum drying to obtain titanium carbide nanosheets; The mass ratio of LiF powder to Ti3AlC2 powder is 1:1; The mass ratio of titanium carbide nanosheets to selenium powder is 500:237; The mass ratio of titanium carbide nanosheets to Fe(NO3)3·9H2O is 250:

303.

2. The preparation method of a two-dimensional titanium carbide supported iron selenide composite electrode catalyst according to claim 1, wherein: The mass ratio of titanium carbide nanosheets to the volume of N, N-dimethylformamide is 2:

5.

3. The preparation method of a two-dimensional titanium carbide supported iron selenide composite electrode catalyst according to claim 1, characterized in that: The volume ratio of N, N-dimethylformamide to hydrazine hydrate is 625:

6.

4. The preparation method of a two-dimensional titanium carbide supported iron selenide composite electrode catalyst according to claim 1, characterized in that: The mass ratio of titanium carbide nanosheets to polyvinylpyrrolidone is 20:

13.

5. The preparation method of a two-dimensional titanium carbide supported iron selenide composite electrode catalyst according to claim 1, characterized in that: The solvothermal reaction time is 12 h; the temperature during freeze-drying is -180 °C, and the drying pressure is 1000 Pa.

6. A two-dimensional titanium carbide supported iron selenide composite electrode catalyst, characterized in that: Prepared by the preparation method described in any one of claims 1-5.

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