CN110681370B

CN110681370B - Molybdenum disulfide/gold/nitrogen-doped carbon nanotube complex and preparation method and application thereof

Info

Publication number: CN110681370B
Application number: CN201910967349.5A
Authority: CN
Inventors: 马淑兰; 杨燕; 史可人; 王惠
Original assignee: Beijing Normal University; Ningxia University
Current assignee: Beijing Normal University; Ningxia University
Priority date: 2019-10-12
Filing date: 2019-10-12
Publication date: 2020-08-14
Anticipated expiration: 2039-10-12
Also published as: CN110681370A

Abstract

The invention relates to a molybdenum disulfide/gold/nitrogen-doped carbon nanotube complex and a preparation method and application thereof. The preparation method comprises the following steps: mixing (Ppy) -MoS₄Putting into a water body, oscillating for 2-5h, centrifuging after adsorption is finished to obtain an adsorption product, and calcining the adsorption product to obtain the catalyst; wherein the water body contains Au (III); the (Ppy) -MoS₄The preparation method comprises the following steps: nano-tube shaped NO₃Preparing (Ppy) as a dispersion in water, (NH)₄)₂MoS₄Dropwise adding into the dispersion, reacting for 60-80h, stirring, vacuum filtering, washing with water and ethanol until the filtrate is colorless, and drying to obtain the final product; the conductivity of the elemental Au obtained by adsorbing the gold ion solution by the polypyrrole and the N-doped carbon nano tube obtained by calcining the Ppy makes up the MoS₂Insufficient conductivity.

Description

Molybdenum disulfide/gold/nitrogen-doped carbon nanotube complex and preparation method and application thereof

Technical Field

The invention relates to the technical field of electrocatalysts, in particular to a molybdenum disulfide/gold/nitrogen-doped carbon nanotube complex and a preparation method and application thereof.

Background

The development of new energy storage materials is particularly concerned by people under the large background of increasingly serious energy crisis. Hydrogen is currently considered to be the most promising clean energy source that can replace fossil energy. The hydrogen energy can be directly obtained through a hydrogen evolution reaction (abbreviated as HER) by electrolysis, and the HER process needs higher overpotential, so that the overpotential can be obviously reduced by a suitable electrocatalyst, and industrial application is realized. To date, noble metals, represented by platinum (Pt), remain the most powerful electrocatalysts. However, the precious metal resources are scarce and expensive, the production cost is very high, and the industrialization of the method is limited. Therefore, the search for highly efficient and stable catalysts has become an important research task.

NiS₂、CoS₂、MoS₂The transition metal sulfides have certain HER catalytic activity, are low in price and easy to obtain, are paid attention to by researchers, but the catalytic performance needs to be improved. In order to improve the catalytic performance of such materials, researchers have adopted various methods, such as compounding with conductive matrix graphene to improve the conductivity of the catalyst, reducing the particle size of the material to expose more catalytic active sites, doping elements to change the electronic structure, and the like. Polypyrrole (Ppy) is an intrinsic conductive polymer containing a conjugated large pi-bond structure, and can be used for preparing a polypyrrole framework with positive charges and conveniently introducing MoS₄ ^2-Anion, polypyrrole can be converted into nitrogen-doped carbon by calcination method to increase the surface area of the catalyst and accelerate electron transfer, and MoS with catalytic activity is obtained₂。

Disclosure of Invention

Based on the above-mentioned drawbacks, the present invention provides a (Ppy) -MoS₄Materials and methods for their preparation.

Unless otherwise specified, Ppy referred to in the present invention is polypyrrole.

Preparation of (Ppy) -MoS₄The method comprises the following steps:

forming a nano tubeNO₃Preparing (Ppy) as a dispersion in water, (NH)₄)₂MoS₄Dropwise adding into the dispersion, reacting for 60-80h, stirring, vacuum filtering, washing with water and ethanol until the filtrate is colorless, and drying.

The (Ppy) -MoS prepared by the method provided by the invention₄Has a large specific surface area, can be used as an adsorbing material to achieve a good adsorbing effect, and the (Ppy) -MoS₄The conductive performance of (2) is excellent.

In the preparation method of the present invention, preferably, the nanotube-shaped NO₃-Ppy and (NH)₄)₂MoS₄The mass ratio of (1): (2-5); more preferably 1: 3.

Under the mass ratio, the nanotube type (Ppy) -MoS can be better prepared₄。

In the preparation method of the present invention, preferably, the nanotube shaped NO₃-Ppy was prepared as follows:

mixing Fe (NO)₃)₃And reacting Methyl Orange (MO) and pyrrole in an ice-water bath for 2-6h to obtain the compound.

Wherein, the Fe (NO)₃)₃And methyl orange in a molar ratio of (4-8): 1; said Fe (NO)₃)₃And pyrrole in a molar volume ratio of (100- & 150): (5-10) mmol/mL.

Preferably, the Fe (NO)₃)₃And methyl orange at a molar ratio of (4.8-7): 1 (most preferably 6: 1); and/or, said Fe (NO)₃)₃And pyrrole in a molar volume ratio of (100- & 150): 7mmol/mL (most preferably 120:7 mmol/mL).

It was verified that nanotubular NO can be obtained without the above-defined limits₃Ppy, but nanotube-shaped NO obtained₃Agglomeration of-Ppy occurs, and the like, so that nanotube-shaped NO having desired superior properties cannot be obtained well₃-Ppy. The inventor does not need to carry out a large amount of experiments to optimize the optimal range ratio.

More specifically, the nanotube-shaped NO of the present invention₃-Ppy was prepared as follows:

mixing Fe (NO)₃)₃Dissolving Methyl Orange (MO) in deionized water, stirring for 0.5-1h, adding pyrrole, stirring in ice-water bath for 2-4h, washing, and drying to obtain black solid, namely nanotube NO₃-Ppy; wherein, the Fe (NO)₃)₃And the molar volume of the deionized water is (0.5-2): 40mmol/mL (more preferably (0.8-1.5): 40mmol/mL, most preferably 1.2: 40 mmol/mL).

The invention also provides (Ppy) -MoS prepared by the preparation method of any one of the technical schemes₄. (Ppy) -MoS provided by the invention₄Has a large specific surface area, thereby having good adsorption performance.

The invention further provides (Ppy) -MoS according to any of the above technical solutions₄Use as an adsorbent; preferably as an adsorbed reducing agent for gold.

The invention also provides a method for adsorbing and reducing gold from the water body, which comprises the following steps: (Ppy) -MoS according to any of the above embodiments₄Is an adsorbent.

The inventors have surprisingly found that (Ppy) -MoS₄The adsorbent can effectively adsorb Au (III) in the water body. The method provided by the invention provides a good solution for solving the problems.

Preferably, the (Ppy) -MoS₄The mass concentration ratio of Au (III) to Au (III) in the water body is (0.01-0.1) g: (10-100) ppm; by way of illustration and explanation, (Ppy) -MoS as described in the present invention₄The mass concentration ratio of Au (III) to Au (III) in the water body is (0.01-0.1) g: (10-100) ppm, and also in equal proportions (0.1-1) g: (100-1000) ppm, (1-10) g: (1000-10000) ppm, and so on.

More preferably, the concentration of Au (III) in the water body is 5-1000 ppm.

The method specifically comprises the following steps: subjecting the (Ppy) -MoS₄Throwing into the water bodyAnd oscillating for 2-5h to obtain the product.

The invention further provides a MoS₂an/Au/N-CNT (molybdenum disulfide/gold/nitrogen doped carbon nanotube) composite and a preparation method thereof.

Specifically, the technical scheme of the preparation method is as follows:

MoS₂The preparation method of the/Au/N-CNT complex comprises the following steps:

subjecting the (Ppy) -MoS₄Putting into a water body, oscillating for 2-5h, centrifuging after adsorption is finished to obtain an adsorption product, and calcining the adsorption product to obtain the catalyst; wherein the water body contains Au (III).

(unless otherwise specified, the N-CNTs referred to herein are nitrogen-doped carbon nanotubes)

Preferably, the (Ppy) -MoS₄The mass concentration ratio of Au (III) to Au (III) in the water body is (0.01-0.1) g: (10-100) ppm; more preferably (0.01-0.1) g: (20-60) ppm; most preferably (0.01-0.1) g: 50 ppm.

More preferably, the concentration of Au (III) in the water body is 5-1000 ppm. Further preferably, the concentration of Au (III) is 30-60 ppm.

The above concentrations allow the MoS to be prepared₂the/Au/N-CNT composite has more excellent performance and is beneficial to the hydrogen evolution performance.

In the preparation method of the invention, preferably, the calcination is carried out at 700-900 ℃ for 3-6h under an inert gas atmosphere. More preferably, calcination is carried out at 800 ℃ for 4h under an inert gas.

The invention also provides the MoS prepared by the preparation method of any one of the technical schemes₂a/Au/N-CNT composite.

In the preparation method provided by the invention, due to the selection and optimization of reagents and conditions, the problem of MoS is solved₂Adding surfactant-methyl orange during polypyrrole synthesis to obtain nitrate radical doped Ppy nanotube, and ion exchange to obtain MoS₄ ^2-Doping polypyrrole nanotubes; the conductivity of the elemental Au obtained by adsorbing the gold ion solution by the polypyrrole and the N-doped carbon nano tube obtained by calcining the Ppy makes up forMoS₂Insufficient conductivity.

The invention further provides the MoS of any one of the technical schemes₂The application of the/Au/N-CNT complex (molybdenum disulfide/gold/nitrogen doped carbon nanotube complex) in the field of HER electrocatalysis.

The preparation method provided by the invention provides a new idea for treating and recycling heavy metal waste liquid, and the material prepared by the preparation method can be converted into a HER electrocatalyst, so that the preparation method has practical application significance.

Of course, not all of the advantages described above need to be achieved at the same time in the practice of any one product or method of the invention.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 shows NO of example 2₃SEM picture of Ppy;

FIG. 2 shows NO of example 3₃SEM picture of Ppy;

FIG. 3 shows NO in examples 4 and 5₃SEM picture of Ppy;

FIG. 4 shows NO of example 1₃SEM picture of Ppy;

FIG. 5 shows (Ppy) -MoS of example 7₄、(Ppy)-MoS₄Adsorption of gold product, (Ppy) -MoS₄Calcined product, (Ppy) -MoS₄XRD pattern of calcined product after gold adsorption, wherein (a) is (Ppy) -MoS₄And (b) is (Ppy) -MoS₄Adsorbing the gold product, (c) is (Ppy) -MoS₄The calcined product (d) is (Ppy) -MoS₄Calcining the product after gold adsorption;

FIG. 6 shows (Ppy) -MoS in example 7₄SEM photographs of the calcined product before and after adsorbing Au, wherein (a, b) is (Ppy) -MoS₄Before Au is adsorbed, (c, d) is adsorptionAfter Au is attached, (e, f) is SEM photograph of calcination product after Au is adsorbed;

FIG. 7 shows (Ppy) -MoS in example 7₄XPS spectrum of calcined product after gold adsorption; wherein (a) is full spectrum, (b) is Au 4f, (C) is Mo 3d, (d) is S2 p, (e) is N1S, and (f) is fine spectrum of C1S.

FIG. 8 shows Au/(Ppy) -MoS as a pre-calcination product in example 7₄XPS spectra of (a); wherein, the left graph is an N fine spectrum, and the right graph is a C fine spectrum;

FIG. 9 is a MoS of the present invention₂HER polarization curve of/Au/N-CNT complex as electrocatalyst, wherein (a) is MoS₂Au/N-CNT, and (b) is MoS₂(ii)/N-CNT and (C) is Pt/C;

FIG. 10 is a MoS of the present invention₂The LSV pattern obtained by repeating the measurement 3 times for the/Au/N-CNT.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

This example provides a (Ppy) -MoS₄The preparation method comprises the following steps:

(1) nanotube shaped NO₃Synthesis of-Ppy

Weigh 1.937g (4.8mmol) Fe (NO)₃)₃·9H₂O, 0.262g (0.8mmol) Methyl Orange (MO) dissolved in 160ml deionized water, stirred for 0.5h, added with 0.28ml pyrrole, stirred for 4h in ice water bath, washed and dried to obtain black solid, namely nano-tube shaped NO₃-Ppy；

(2) Synthesis of (Ppy) -MoS by ion exchange method₄

Synthesis of (Ppy) -MoS by ion exchange method₄. Adding 0.15g NO₃Adding 5ml of water into Ppy, and performing ultrasonic treatment to obtain a dispersion liquid. 0.45g (NH)₄)₂MoS₄Adding 10ml water, ultrasonic dissolving, and adding above NO dropwise₃Stirring the Ppy dispersion liquid, and reacting for 72 hours at normal temperature. With stirring, the system gradually changed from black to brown. Filtering, washing with large amount of water and ethanol until the filtrate is colorless to obtain black solid, and drying to obtain (Ppy) -MoS₄。

Example 2

This example provides a (Ppy) -MoS₄Compared with example 1, the difference is only: in the step (1), the dosage of methyl orange is 0.5 mmol.

Example 3

This example provides a (Ppy) -MoS₄Compared with example 1, the difference is only: in the step (1), the reaction was carried out directly at room temperature without using an ice-water bath.

Example 4

This example provides a (Ppy) -MoS₄Compared with example 1, the difference is only: in the step (1), stirring in ice-water bath for 24 h.

Example 5

This example provides a (Ppy) -MoS₄Compared with example 1, the difference is only: in the step (1), stirring for 6 hours in ice-water bath.

The following characteristics are given for the combined examples 1 to 5:

example 1 and example 2 only differ in the amount of methyl orange, and when the amount of methyl orange is 0.5mmol, the NO obtained is prepared₃the-Ppy has two forms of particles and nano-tubes, and agglomeration phenomenon occurs. As shown at a and b in figure 1.

Example 1 and example 3 differ only in the reaction temperature, and when the reaction is carried out at room temperature, particulate NO is obtained₃-Ppy, SEM pictures are shown as a, b in FIG. 2.

Example 1 and examples 4, 5 differ only in reaction time. When the reaction time is 24h, the nanotube-shaped NO can be generated₃Ppy, but agglomeration, as shown by a, b in FIG. 3; when the reaction time is shortened to 6h, NO is produced₃The Ppy is still in the shape of a nanotube and can be clearly seen from the broken notchThe hollow structure is seen, confirming that the nanotubes are hollow, but the agglomeration phenomenon still exists, as shown in c, d in fig. 3.

NO obtained as prepared in example 1₃SEM photograph of-Ppy As shown in FIG. 4, it can be seen that NO was produced by the method provided in example 1₃the-Ppy has a good structure, so that (Ppy) -MoS with a good structure can be obtained₄。

Example 6

This example provides a method for adsorbing and reducing gold from a body of water, as in (Ppy) -MoS provided in example 1₄Is an adsorbent.

The method specifically comprises the following steps:

first, 1g of chloroauric acid (HAuCl)₄·3H₂O) is dissolved in 10ml deionized water to prepare a solution with the concentration of 0.1g/ml, 100 mul is taken and added into a 100ml volumetric flask to prepare 100ml of a solution containing 50ppm Au (III), 30ml of the solution is taken and 0.03g (Ppy) -MoS is added₄The complex was shaken for 3 h.

Example 7

The present embodiment provides a MoS₂the/Au/N-CNT complex and the preparation method thereof specifically comprise the following steps:

(1) nanotube shaped NO₃Synthesis of-Ppy

(2) Synthesis of (Ppy) -MoS by ion exchange method₄

Synthesis of (Ppy) -MoS by ion exchange method₄. Adding 0.15g NO₃Adding 5ml of water into Ppy, and performing ultrasonic treatment to obtain a dispersion liquid. 0.45g (NH)₄)₂MoS₄Adding 10ml water, ultrasonic dissolving, and adding above NO dropwise₃Stirring the Ppy dispersion liquid, and reacting for 72 hours at normal temperature. With stirring, the system gradually changed from black to brown. Filtering, washing with large amount of water and ethanol until the filtrate is colorless to obtain black solid, and drying to obtain (Ppy) -MoS₄；

(3)(Ppy)-MoS₄Adsorbing chloroauric acid and reducing to simple substance Au

First, 1g of chloroauric acid (HAuCl)₄·3H₂O) is dissolved in 10ml deionized water to prepare a solution with the concentration of 0.1g/ml, 100 mul is taken and added into a 100ml volumetric flask to prepare 100ml of a solution containing 50ppm Au (III), 30ml of the solution is taken and 0.03g (Ppy) -MoS is added₄Complex, shaking for 3 h; centrifuging after the adsorption is finished, taking the solid, washing the solid with water and ethanol, and drying to obtain an adsorption product Au/(Ppy) -MoS₄；

(4)MoS₂Preparation of/Au/N-CNT

Calcining the adsorption product obtained in the step (3) for 4 hours at 800 ℃ under inert gas to obtain MoS₂a/Au/N-CNT composite.

Meanwhile, the present embodiment provides the following characterizing information:

XRD pattern:

(Ppy) -MoS obtained in step (2)₄As shown in fig. 5 (a), no significant diffraction peak was observed.

(Ppy)-MoS₄After adsorbing 35ppm chloroauric acid solution for 3h, the XRD spectrum of the adsorbed solid is shown as (b) in FIG. 5, and a face-centered cubic Au diffraction peak (PDF card number: 04-0784) appears, which indicates that Au (III) in the solution is reduced to Au simple substance.

In contrast, the inventors additionally adsorbed no sample, i.e. (Ppy) -MoS₄Direct calcination (calcination at 800 ℃ for 4h in an inert atmosphere) was carried out, and the XRD spectrum of the product is shown in (c) of FIG. 5, in which hexagonal phase MoS was observed₂(PDF card No. 37-1492) showing MoS of Ppy precursor₄ ^2-Can be converted into MoS by calcination₂。

The adsorption product Au/(Ppy) -MoS obtained in the step (3) is used₄Calcination at 800 ℃ for 4h in an inert atmosphere, as shown in FIG. 5 (d), except that hexagonal phase MoS appears₂Besides, obvious diffraction peaks of the Au simple substance are observed at the same time.

The above results demonstrate that (Ppy) -MoS can be successfully prepared by calcination₄And the adsorption product Au/(Ppy) -MoS₄Conversion of molybdenum sulfide to MoS₂While the adsorption process can be obtainedAnd (5) gold.

By way of illustration and explanation, the asterisks in FIG. 5 indicate MoS₂Diffraction peaks of the phases, diamonds represent diffraction peaks of the Au crystal phase.

SEM photograph:

FIG. 6 shows (Ppy) -MoS₄SEM photographs of samples before and after gold adsorption and after calcination of the adsorbed product. As can be seen from (a) and (b) in FIG. 6, (Ppy) -MoS₄Has a nano-tube shape (the diameter is about 200nm) and has a smooth surface. After adsorbing the chloroauric acid solution for 3 hours, the morphology of the solid sample is shown in (c) and (d) in fig. 6, and it can be seen that a large number of gold particles (particle diameter 80-100nm, marked by circles in the figure) are attached to the surface of the nanotube, which indicates that the reduced Au simple substance is loaded on the Ppy nanotube in the form of nanoparticles after adsorption. After calcination, the morphology was substantially maintained, as shown in (e), (f) of FIG. 6, and a large number of Au particles were attached to the nanotubes, and MoS appeared around the nanotubes₂Nanoplatelets (indicated by arrows in the figure).

XPS characterization:

to further study the elemental composition and chemical state of the calcined sample of the adsorbed product, the sample was characterized using XPS. From the (a) -full spectrum in FIG. 7, it can be seen that (Ppy) -MoS₄The presence of the elements Au, S, Mo, C, N, O in the calcined product after gold adsorption may be due to partial oxidation of the surface of the sample upon exposure to air.

FIG. 7 (b) shows 4f of elemental Au_5/2(87.7eV) and 4f_7/2The binding energy (84.1eV) indicates that Au exists in the elementary substance after being reduced.

As shown in (c) of FIG. 7, the characteristic peaks at 232.0 and 228.8eV are assigned to MoS, respectively₂Middle Mo⁴⁺Mo 3d of_3/2And Mo 3d_5/2The binding energy of (c); the peak at 226.2eV corresponds to the binding energy of S2S.

The above results all prove that the molybdenum in the calcined product is MoS₂The form exists. The very weak peaks with binding energies of 235.3 and 233.1eV correspond to Mo 3d bound to oxygen (Mo-O)_3/2And Mo 3d_5/2The binding energy of (a) is due to oxidation of part of the surface of the sample exposed to air, and the weak of the two peaks indicates a very small amount of the binding energy.

Peaks at 162.4 and 163.6eV in (d) in FIG. 7 correspond to S ^2-2p of_3/2And 2p_1/2Further demonstrates the MoS after calcination₂Is present.

Fig. 7 (e) is a fine spectrum of the N1s region, with peaks at 398.7, 400.1, and 401.0eV corresponding to the binding energies of pyridine nitrogen (pyridine N), pyrrole nitrogen (pyrolic N), and graphite nitrogen (graphtic N), respectively, indicating that the calcined carbon nanotubes are N-doped carbon. The peak at 394.9eV corresponds to the binding energy of Mo 3 p.

As shown in fig. 7 (f) is a fine spectrum of the C1s region, and peaks at 284.6, 284.9, 285.8 and 288.1eV are binding energies of C1s corresponding to C — C, C-N, C — N bonds, respectively.

Comparative analysis of the Pre-calcination product Au/(Ppy) -MoS₄The XPS spectrum of (1) as shown in FIG. 8 shows that, in the N-fine spectrum (left panel a in FIG. 8), peaks at 396.2, 399.6 and 401.6eV correspond to imine (═ N-), amine (-NH-) and positively charged amine (-NH-) of the pyrrole ring, respectively⁺-) N1s binding energy. In the C fine spectrum (right panel b in fig. 8), 284.2 and 284.6eV correspond to C ═ C and C — C bond C1s binding energies of the pyrrole ring, and 285.7 and 287.6eV correspond to C-N, C ═ N bond C1s binding energies.

Comparing FIGS. 7 (post-calcination product) and 8 (pre-calcination product), it can be seen from a comparison of XPS fine spectra of N and C before and after calcination that Ppy was converted to nitrogen-doped carbon by calcination, indicating that the adsorbed gold product was successfully converted to MoS by calcination₂/Au/N-CNT。

Test example 1

This experimental example provides the results of the ICP test for Au adsorption of example 1.

The adsorption was performed according to the method of example 6, and after completion of the adsorption, centrifugation was carried out, and the supernatant was taken out by a syringe for ICP measurement.

(Ppy) -MoS of example 1 was calculated according to the formulas (1) and (2)₄Removal rate and distribution coefficient K for Au (III)_d。

Wherein C is₀And C_fInitial and equilibrium concentrations of Au (III) (ppm,. mu.g/mL), respectively, V is the solution volume (mL) and m is the mass of the adsorbent (g).

Wherein, the formulas (1) and (2) are as follows:

removal rate (%) ═ C₀-C_f)/C₀×100％ (1)

K_d＝(V[(C₀-C_f)/C_f])/m (2)

As can be seen from the data in Table 1 above, (Ppy) -MoS of example 1₄Has good effect of removing Au (III), the adsorption rate can reach 99.99 percent and approach 100 percent when the initial concentration of Au is 35ppm, and the distribution coefficient K_dThe value is very large (3.5 × 10)⁷mL/g), description (Ppy) -MoS₄Has good adsorption effect on Au (III).

The research shows that the MoS is possible₄The soft-phase affinity of the S group (S) with the Au (III) ion and the reducibility of Ppy to the Au (III) ion both contribute to the adsorption of Au (III).

Test example 2

This test example provides the MoS prepared in example 7₂And testing the performance of the/Au/N-CNT composite body as an electrocatalyst.

The experimental method comprises the following steps: adopts a traditional three-electrode system (graphite rod electrode as a counter electrode, SCE electrode as a reference electrode, the diameter of 3mm and the area of 0.07 cm)^-2The glassy carbon electrode as a working electrode), wherein the slurry is prepared by the following steps: 4mg of the catalyst sample was dispersed in a mixed solution of 1mL of water, ethanol and 5 wt% Nafion solution (binder) (3:1:0.34v/v/v), and after 30 minutes of ultrasonication, 8. mu.L of the slurry was dropped on a glassy carbon electrode, and allowed to stand under an infrared lamp until dried, with a catalyst loading of 0.46mgcm^-2。

HER test is 0.5M H₂SO₄The sweep rate is 5mV^-1。

The experimental results are as follows: as shown in fig. 9.

As shown in FIG. 9 (a), MoS₂the/Au/N-CNT shows better HER catalytic activity, and the overpotential of 318mV is only needed to reach 10mAcm^-2The current density of (1).

As can be seen from (b) in FIG. 9, the MoS obtained by direct calcination of the unadsorbed gold sample₂The HER catalytic performance of the/N-CNT is very poor, and the current density is 10mA cm^-2The overpotential is 596 mV.

As can be seen from (c) in FIG. 9, MoS is compared with that of the commercial catalyst₂the/Au/N-CNT has better HER catalytic activity.

Test example 3

This test example provides the MoS prepared in example 7₂the/Au/N-CNT complex is used as a repeatability test of the electrocatalyst.

The results are shown in FIG. 10.

As can be seen from FIG. 10, the MoS test was repeated₂Electrocatalysis of/Au/N-CNT three times, reaching 10mAcm^-2The overpotentials required by the current density are 320mV, 318mV and 323mV respectively, thus the MoS provided by the invention₂the/Au/N-CNT complex has better repeatability.

The MoS provided by the invention is synthesized by integrating the embodiments and the test examples₂The HER performance was nearly doubled compared to the Au/N-CNT complex before gold adsorption (nearly doubled overpotential reduction at the same current density). Illustrated by (Ppy) -MoS₄The adsorbent is used for adsorbing and reducing Au (III), so that the pollution of gold-containing waste liquid to the environment is solved, the precious metal material is enriched and recovered, and meanwhile, the adsorbent can be used as a hydrogen evolution electrocatalyst, the HER catalytic activity is improved, and high-efficiency MoS is obtained₂a/Au/N-CNT composite catalyst.

Although the invention has been described in detail hereinabove by way of general description, specific embodiments and experiments, it will be apparent to those skilled in the art that many modifications and improvements can be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.

Claims

1. MoS with hydrogen evolution performance₂The preparation method of the/Au/N-CNT complex is characterized by comprising the following steps:

1) mixing Fe (b), (c), (d), (NO₃)₃Reacting methyl orange and pyrrole in ice water bath for 2-6h to prepare nano tubular NO₃-Ppy, said Fe (NO)₃)₃And methyl orange at a molar ratio of (4.8-7): 1; said Fe (NO)₃)₃And pyrrole in a molar volume ratio of (100- & 150): 7 mmol/mL;

2) nano-tube shaped NO₃Preparing (Ppy) as a dispersion in water, (NH)₄)₂MoS₄Dropping into the dispersion, the nano-tube shaped NO₃-Ppy and (NH)₄)₂MoS₄The mass ratio of (1): (2-5); reacting for 60-80h, stirring, filtering, washing with water and ethanol until the filtrate is colorless, and drying to obtain (Ppy) -MoS₄；

3) The resulting (Ppy) -MoS₄Putting the powder into a water body containing Au (III), oscillating for 2-5h to adsorb Au (III), centrifuging after adsorption is finished to obtain an adsorption product, and calcining the adsorption product for 3-6h under the inert gas atmosphere at the temperature of 700-900 ℃, wherein the concentration of Au (III) in the water body is 5-1000 ppm; the (Ppy) -MoS₄The mass concentration ratio of Au (III) to Au (III) in the water body is (0.01-0.1) g: (10-100) ppm.

2. The method of claim 1, wherein the nanotube-shaped NO₃-Ppy and (NH)₄)₂MoS₄The mass ratio of (A) to (B) is 1: 3.

3. The method according to claim 1, wherein the concentration of au (iii) is 30 to 60 ppm;

the (Ppy) -MoS₄The mass concentration ratio of Au (III) to Au (III) in the water body is (0.01-0.1) g: (20-60) ppm.

4. MoS₂The Au/N-CNT composite, which is produced by the production method according to any one of claims 1 to 3.

5. The MoS of claim 4₂HER electrocatalytic activity of/Au/N-CNT complexApplication in chemical field.