A method for preparing a nanocatalyst for the reduction reaction of p-nitrophenol

Abstract

The invention relates to the technical field of catalyst preparation, and specifically discloses a method for preparing a nanocatalyst for the reduction reaction of p-nitrophenol. The method specifically comprises the following steps: S1, preparation of MoS2: S101, adding 1 mmol of ammonium heptamolybdate and 30 mmol of thiourea to 40 mL of deionized water, and magnetically stirring for 30 minutes; S102, pouring the stirred transparent solution into a stainless steel polytetrafluoroethylene-lined autoclave, and heating at 200 DEG C for 12 hours; S103, centrifuging the obtained sample, washing it with pure water and ethanol, and drying it at 80 DEG C for 8 hours to obtain MoS2; S2, preparation of CoMoS2: S201, adding 1 mmol of a mixture containing ammonium heptamolybdate and cobalt chloride hexahydrate, and 30 mmol of thiourea to 40 mL of deionized water, and magnetically stirring for 30 minutes. In the invention, the synthesized Au / CoMoS2 catalyst exhibits excellent catalytic activity and has a short reaction processing time.

Description

Technical Field

[0001] The invention relates to the technical field of catalyst preparation, in particular to a method for preparing a nano catalyst for p-nitrophenol reduction reaction. Background Art

[0002] Nitrophenol compounds have become one of the main sources of water pollution due to their high toxicity, good water solubility and stability. Particularly 4-nitrophenol (4-NP), as a major pollutant in the pharmaceutical and dye industries, finding a method to control and process it seems particularly urgent. And in the prior art, there is a variety of methods for processing 4-NP, specifically including adsorption, biodegradation, electrochemical removal and chemical reduction etc. However, in actual use, it is found that these methods have the problem of long processing time. Summary of the Invention

[0003] In view of the technical problem that the processing time in the prior art methods is too long, the present invention provides a method for preparing a nanocatalyst for the reduction reaction of p-nitrophenol.

[0004] The technical solution adopted by the present invention is: a method for preparing a nanocatalyst for the reduction reaction of p-nitrophenol, which specifically comprises the following steps:

[0005] Preparation of S1, MoS2:

[0006] S101, adding 1 mmol of ammonium heptamolybdate and 30 mmol of thiourea to 40 mL of deionized water and magnetically stirring for 30 minutes;

[0007] S102, pouring the stirred transparent solution into a stainless steel polytetrafluoroethylene-lined autoclave and heating it at 200° C. for 12 hours;

[0008] S103, the obtained sample was centrifuged and washed with pure water and ethanol, and dried at 80 °C for 8 h to obtain MoS2;

[0009] S2, CoMoS2 preparation:

[0010] S201, adding 1 mmol of a mixture containing ammonium heptamolybdate and cobalt chloride hexahydrate and 30 mmol of thiourea to 40 mL of deionized water, and magnetically stirring the mixture for 30 minutes;

[0011] S202, pouring the stirred transparent solution into a stainless steel polytetrafluoroethylene-lined autoclave and heating it at 200° C. for 12 hours;

[0012] S203, the obtained sample was centrifuged and washed with pure water and ethanol, and dried at 80°C for 8 hours to obtain CoMoS2;

[0013] Preparation of S3, Au / MoS2 and Au / CoMoS2 catalysts:

[0014] S301, anchoring Au nanoparticles on the support by NaBH4 reduction:

[0015] The details are as follows: 40 mg of MoS2 or CoMoS2 was ultrasonically dispersed into 20 mL of a mixed solution of water and ethanol, wherein the volume ratio of water to ethanol was 18:2; 5.17 mL of HAuCl4 solution with a molar concentration of 0.01 mol / L was added to the above mixed solution and magnetically stirred for 24 hours; 30 mg of NaBH4 was added to the above mixture and magnetically stirred for 1 hour; finally, the product was separated, washed with pure water and ethanol and dried at 80°C for 8 hours to obtain Au / MoS2 and Au / CoMoS2 nanocomposites.

[0016] The present invention is further configured such that, in step S3, M Co :M Mo The molecular ratio ranges from 1:9 to 4:6.

[0017] The present invention is further configured to include a catalytic reaction experiment, the specific steps of which are as follows:

[0018] 3 mL of 4-NP solution (0.1 mmol / L) was added to a quartz cuvette, followed by 0.15 mL of NaBH4 solution (0.1 mol / L). After thorough mixing, 1 mg of Au / MoS2 or Au / CoMoS2 catalyst was added to initiate the catalytic reduction reaction. The progress of the reduction reaction was monitored by monitoring the UV-visible absorption spectrum (400 nm) of 4-NP at different reaction times.

[0019] The present invention is further configured to further include testing the crystal structure of the catalyst using an X-ray diffractometer under Cu radiation at 40 kV and 30 mA, the specific steps being as follows:

[0020] First, the XRD patterns of different samples were measured by scanning in the angle range of 5–90° (2θ) at a speed of 5° / min;

[0021] Secondly, the morphology of the catalyst was characterized by obtaining SEM images on a field emission scanning electron microscope to observe the catalyst morphology, and the elemental spectrum was analyzed by an energy dispersive X-ray (EDX) elemental analysis system.

[0022] Again, transmission electron microscopy (TEM) images were obtained by a Tecnai G220 TWIN microscope operated at 200 kV;

[0023] Subsequently, Raman spectra were measured on a Renishaw Raman microspectrometer;

[0024] Finally, X-ray photoelectron spectroscopy was performed on a ThermoFischer ESCALAB Xi+ using an Al K monochromatic light source to obtain elemental information.

[0025] The beneficial effects of the present invention are as follows: in the present invention, a series of CoMoS2 samples with different Co and Mo molar ratios are prepared by introducing Co as a heteroatom, and used to anchor gold nanoparticles, and the synthesized Au / CoMoS2 catalysts show excellent catalytic activity, especially when the molar ratio of Co to Mo is 2:8, the Au / CoMoS2 (M Co :M Mo =2:8) showed the best catalytic performance, and its apparent rate constant (k app ) can reach 1.063. The physicochemical properties of the catalyst were analyzed in detail using a series of characterization methods, including XRD, SEM, TEM, Raman spectroscopy, and XPS. This analysis also discusses the role of cobalt in promoting the catalytic reduction of 4-NP over the Au / CoMoS2 catalyst. In summary, the present invention synthesizes cobalt-modified MoS2 via a simple hydrothermal method, which serves as a perfect support for Au nanoparticles to prepare a catalytic system with enhanced activity for the 4-NP reduction reaction, while also shortening the reaction time. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the preparation process of CoMoS2 and Au / CoMoS2, and the catalytic application of 4-NP reduction to 4-AP;

[0027] Figure 2a -f is the UV-visible absorption spectrum (ae) of the NaBH4-catalyzed reduction of p-NP and the ln(C t / C0) versus reaction time (t) (f);

[0028] Figure 3a -b is a series of X-ray diffraction patterns of CoMoS2 (a) and Au / CoMoS2 (b);

[0029] Figure 4a -b is the Raman spectra of Au / MoS2 and Au / CoMoS2, where the molar ratio of Co / Mo varies from 1:9 to 4:6;

[0030] Figure 5a -b is the UV-visible absorption spectra of MoS2 and Au / MoS2 (a); UV-visible absorption spectra of CoMoS2 (2 / 8) and Au / CoMoS2 (2 / 8) (b);

[0031] Figure 6a-k are morphological diagrams of the synthesized samples: SEM images of MoS2 (a), Au / MoS2 (b), CoMoS2 (2 / 8) (c) and Au / CoMoS2 (2 / 8) (d); TEM images of MoS2 (e), Au / MoS2 (f), CoMoS2 (2 / 8) (h) and Au / CoMoS2 (2 / 8) (i); size distribution of Au nanoparticles of Au / MoS2 (g) and Au / CoMoS2 (2 / 8) (j); SEM spectrum of Au / CoMoS2 (2 / 8) (k);

[0032] Figure 7a -c are XPS spectra of Au / MoS2 and Au / CoMoS2(2 / 8), respectively (a) Au 4f; (b) Mo 3d; (c) S2P. DETAILED DESCRIPTION

[0033] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0034] refer to Figure 1 -7. In order to solve the problems existing in the background technology, the present application proposes the following technical solution: a method for preparing a nanocatalyst for the reduction reaction of p-nitrophenol, which specifically comprises the following steps:

[0035] Preparation of S1, MoS2 (synthesized by hydrothermal method):

[0036] S101, adding 1 mmol of ammonium heptamolybdate and 30 mmol of thiourea to 40 mL of deionized water and magnetically stirring for 30 minutes;

[0037] S102, pouring the stirred transparent solution into a stainless steel polytetrafluoroethylene-lined autoclave and heating it at 200° C. for 12 hours;

[0038] S103, the obtained sample was centrifuged and washed with pure water and ethanol, and dried at 80 °C for 8 h to obtain MoS2;

[0039] S2, CoMoS2 preparation (synthesized by hydrothermal method):

[0040] S201, adding 1 mmol of a mixture containing ammonium heptamolybdate and cobalt chloride hexahydrate and 30 mmol of thiourea to 40 mL of deionized water, and magnetically stirring the mixture for 30 minutes;

[0041] S202, pouring the stirred transparent solution into a stainless steel polytetrafluoroethylene-lined autoclave and heating it at 200° C. for 12 hours;

[0042] S203, the obtained sample was centrifuged and washed with pure water and ethanol, and dried at 80°C for 8 hours to obtain CoMoS2;

[0043] Preparation of S3, Au / MoS2 and Au / CoMoS2 catalysts:

[0044] S301, anchoring Au nanoparticles on the support by NaBH4 reduction:

[0045] Specifically, 40 mg of MoS2 or CoMoS2 was ultrasonically dispersed in 20 mL of a mixed solution of water and ethanol, wherein the volume ratio of water to ethanol was 18:2. 5.17 mL of a 0.01 mol / L HAuCl4 solution was added to the mixed solution and magnetically stirred for 24 h. 30 mg of NaBH4 was added to the mixture and magnetically stirred for 1 h. Finally, the product was separated, washed with pure water and ethanol, and dried at 80°C for 8 h to obtain Au / MoS2 and Au / CoMoS2 nanocomposites.

[0046] The products used in the present invention are as follows: ethanol (C2H5OH), chloroauric acid (HAuCl4·4H2O), sodium borohydride (NaBH4), and cobalt chloride hexahydrate (CoCl2·6H2O) were purchased from Aladdin Industrial Co., Ltd. (Shanghai, China). 4-Nitrophenol (C6H5NO3), ammonium molybdate tetrahydrate ((NH4)6Mo7O 24 ·4H2O) and thiourea (CH4N2S) were purchased from Merck (Darmstadt, Germany).

[0047] In step S3, M Co :M Mo The molecular ratio ranges from 1:9 to 4:6.

[0048] Experimental example

[0049] Experimental Example 1 also includes a catalytic reaction experiment (UV-visible spectroscopy), and the specific steps are as follows:

[0050] 3 mL of 4-NP solution (0.1 mmol / L) was added to a quartz cuvette, followed by 0.15 mL of NaBH4 solution (0.1 mol / L). After thorough mixing, 1 mg of Au / MoS2 or Au / CoMoS2 catalyst was added to initiate the catalytic reduction reaction. The progress of the reduction reaction was monitored by monitoring the UV-visible absorption spectrum (400 nm) of 4-NP at different reaction times.

[0051] Experimental Example 2:

[0052] The crystal structure of the catalyst was also tested using an X-ray diffractometer (XRD 6000, Shimadzu, Japan) under Cu radiation at 40 kV and 30 mA. The specific steps are as follows:

[0053] First, the XRD patterns of different samples were measured by scanning in the angle range of 5–90° (2θ) at a speed of 5° / min;

[0054] Secondly, the morphology of the catalysts was observed using a field emission scanning electron microscope (FE-SEM) (model SU8010, Hitachi, Japan), and the elemental spectrum was analyzed using an energy dispersive X-ray (EDX) elemental analysis system.

[0055] Again, transmission electron microscopy (TEM) images were obtained by a Tecnai G220 TWIN microscope operated at 200 kV;

[0056] Subsequently, the Raman spectra were measured on a Renishaw Raman microspectrometer (model invia, UK);

[0057] Finally, X-ray photoelectron spectroscopy was performed on a ThermoFischer ESCALAB Xi+ using an Al K monochromatic light source (hv = 1486.6 eV) to obtain elemental information.

[0058] Experimental case analysis:

[0059] Testing of the catalytic performance of 4-NP reduction:

[0060] The catalytic effect of the synthesized catalyst on the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) was evaluated by UV-visible spectroscopy. 4-NP showed a characteristic absorption peak at 320 nm. With the addition of NaBH4, the absorption peak shifted to 400 nm, forming p-nitrophenolate ions. In the control group without the addition of the catalyst, the peak at 320 nm did not change even after a considerable period of time.

[0061] After adding the catalyst, refer to Figures 2a-2e As shown in the figure, the peak of 4-AP at 400nm gradually decays, while the peak of 4-AP at 300nm gradually increases. For different catalysts, the decay rate of the peak at 400nm is different. Among them, Au / MoS2 has the lowest catalytic activity. After adding cobalt to the catalyst, the activity of various Au / CoMoS2 catalysts is improved to a certain extent. Au / CoMoS2 (2 / 8) with a Co / Mo molar ratio of 2 / 8 shows the highest activity, which can complete the conversion of 4-NP to 4-AP within 4 minutes.

[0062] By plotting ln(C t The relationship between C0 and C0) and reaction time is used to study the kinetics of the catalytic reaction. t are the 4-NP concentrations at the initial moment and t minutes, respectively. Figure 2f As shown, the apparent rate constant (k app ) was calculated based on the slope of the fitting curve, and the data are listed in Table 1;

[0063] k of Au / CoMoS2(2 / 8) app 1.063 min -1 , Table 2 lists the comparison of Au / CoMoS2(2 / 8) with some other Au-based catalysts reported in the literature. The results show that the synthesized Au / CoMoS2(2 / 8) catalyst exhibits excellent performance in 4-NP reduction;

[0064] catalyst <![CDATA[K app (min -1 )]]> <![CDATA[Au / MoS2]]> 0.083 <![CDATA[Au / CoMoS2(1 / 9)]]> 0.234 <![CDATA[Au / CoMoS2(2 / 8)]]> 1.063 <![CDATA[Au / CoMoS2(3 / 7)]]> 0.426 <![CDATA[Au / CoMoS2(4 / 6)]]> 0.235

[0065] Table 1: Apparent rate constants (k app ).

[0066]

[0067]

[0068] Table 2: Comparison of catalyst Au / CoMoS2 (2 / 8) with other catalysts.

[0069] Among them, Figure 3 shows the XRD patterns (X-ray diffraction patterns) of MoS2 and a series of Au / CoMoS2 samples. Figure 3a It can be observed that MoS2 shows XRD peaks at 14.3°, 33.7°, 40.1° and 59.2°, corresponding to the (002), (100), (103) and (110) crystal planes, respectively, which include the characteristic peaks of 1T-MoS2 (2θ=33.7°) and 2H-MoS2 (2θ=40.1o);

[0070] Therefore, the synthesized MoS2 contains both 1T and 2H phases. For a series of CoMoS2 samples with different Co / Mo ratios, their diffraction peaks are almost the same as those of MoS2. No new diffraction peaks are shown after the addition of cobalt, which means that the CoMoS2 support maintains the crystal structure of MoS2, and cobalt is more evenly dispersed in the prepared catalyst or the cobalt particles are relatively small.

[0071] like Figure 3bAs shown in the figure, after Au was loaded on a series of samples, some new peaks appeared at 38.5°, 44.6°, 64.8°, 77.9° and 82.1°. The appearance of these peaks was attributed to the diffraction effect of Au nanoparticles, corresponding to the (110), (200), (220), (311) and (222) crystal planes, respectively, which indicated that Au was successfully loaded on MoS2 and CoMoS2.

[0072] Among them, in the prior art, Raman spectroscopy has been used to characterize the interface quality of MoS2, which is affected by strain, defects and dislocations; Figure 4a As shown, two Raman bands of MoS2 were observed, located at 379.7 cm -1 404.8cm -1 They are respectively attributed to the in-plane E 1 2g Mode and out-of-plane A 1g Mode; E 1 2g The mode originates from the opposite vibrations of two S atoms relative to the Mo atoms in the basal plane. 1g The mode originates from the out-of-plane vibration of the Mo-S bond;

[0073] from Figure 4a It can be observed that the E of CoMoS2(2 / 8) 1 2g The mode shifts 1.1cm to a lower angle -1 , which may be caused by the dislocation or defects of Mo and S atoms, which also causes more active edge sites to be exposed and improves the catalytic activity; the spectrum of Au / CoMoS2(2 / 8) shows a rather broad and weak E 1 2g band, which indicates the presence of crystal defects in the basal plane. The typical E 1 2g and A 1g The spectral bands were blue-shifted to 381.1 cm -1 and 407.3cm -1 , which reveals the effect of metal doping on MoS2;

[0074] Although Au / MoS2 does not blue-shift but red-shifts after Au loading, this difference may be due to the effect of cobalt addition on the structure and composition of MoS2. Figure 4b A series of Au / MoS2(1 / 9-4 / 6), E 1 2g and A 1g The peak of E is basically the same as that of Au / CoMoS2(2 / 8). 12g and A 1g The distance between them is a signal of the number of MoS2 layers. The distance will increase with the increase of MoS2 layers. The distances of a series of Au / CoMoS2 samples and Au / MoS2 are 25.6 cm and 25.6 cm, respectively. -1 and 24.1cm -1 , these values ​​are consistent with those reported for the three-layer structure.

[0075] Among them, the UV-Vis spectra of MoS2, Co-doped CoMoS2 (2 / 8), and Au-loaded samples are shown in Figure 5;

[0076] MoS2 and CoMoS2 (2 / 8) at 550nm -1 There is an adsorption peak near the surface of the Au nanoparticles, and after the Au nanoparticles are loaded, the peak red-shifts to 590 nm. -1 This indicates that the band gap of MoS2 is narrowed. This phenomenon reveals that there is a strong metal-support interaction between Au and the support. During the catalytic reduction of 4-NP, the reaction involves the adsorption process of 4-NP and borohydride on the catalyst surface, as well as the electron transfer between the catalyst and the reactants or reaction products. The narrowing of the support's band gap helps electron transport, thereby further promoting the catalytic reaction.

[0077] Among them, it can be seen from the SEM images shown in Figure 6 (ad) that both the synthesized MoS2 and the cobalt-doped MoS2 exhibit nanosheet structures with rich edges. The nanosheets aggregate to form flower-like nanoclusters with a diameter of about 1 μm, and it can be concluded that the loading of Au nanoparticles on the sample does have a significant effect on the sample morphology;

[0078] The nanosheet structures of MoS2 and CoMoS2 can be further confirmed by TEM images (Figure 6(e,h)). After loading Au nanoparticles on these supports, as shown in Figure 6(f,i), it can be observed that the Au nanoparticles are uniformly dispersed on the nanosheets, and the size of the Au nanoparticles is mainly distributed in the range of 5-20 nm.

[0079] Figure 6g and Figure 6h The size distribution of Au nanoparticles was summarized, and the average Au particle sizes of Au / MoS2 and Au / CoMoS2 (2 / 8) were 10.70 nm and 9.15 nm, respectively;

[0080] like Figure 6k In the EDX analysis of Au / CoMoS2 (2 / 8) shown, the elemental mapping of Mo, Co, and Au confirmed that the Au nanoparticles were successfully and uniformly loaded on the surface, while cobalt was highly dispersed in MoS2, which is consistent with the XRD results.

[0081] Among them, in order to explore the surface valence state of elements, XPS spectroscopy was used to characterize two typical catalysts Au / MoS2 and Au / CoMoS2; Figure 7a The Au 4f spectra of the two catalysts are shown, where the peak at 84.1 eV corresponds to the (4f 7 / 2 ), and 87.8 eV corresponds to the (4f 5 / 2 ), which is similar to the metal gold (Au 0 ) features, for Au / CoMoS2, its binding energy decreases slightly, by about 0.1eV, which may be due to the interaction between Au and Co;

[0082] like Figure 7b In the Mo 3d spectrum shown, the double peaks at 232.4 eV and 229.2 eV correspond to Mo 4+ 3d 3 / 2 and Mo 4+ 3d 5 / 2 Characteristic peaks, these two peaks are Mo 4+ Characteristic peaks associated with sulfur, despite the presence of Mo 4+ There are also double peaks at 235.8eV and 233.3eV, corresponding to Mo 6+ 3d 3 / 2 and Mo 6+ 3d 5 / 2 characteristic peaks;

[0083] In summary, the appearance of these peaks indicates that MoS2 has been oxidized, which is caused by the reactivity of the synthesized catalyst, especially at the edge sites. 6+ The ratio is higher than that of Au / MoS2, which indicates that Co improves the reactivity of the catalyst by creating more active edge sites, which is consistent with the results of Raman spectroscopy;

[0084] Figure 7c The double peaks of S2p are shown, located at 163.2eV and 162.0eV, respectively. These two peaks correspond to S2p 1 / 2 and S2p 3 / 2 , indicating the presence of divalent sulfide ions; in addition, the oxidized species of S also appeared at 168.5 eV, which may be the result of partial oxidation of the active surface, more specifically, the oxidation of exposed sulfur atoms at the edge sites.

[0085] It is well known that sulfur atoms at the edge of the catalyst are active sites for catalytic reactions. The sulfur oxide peak area of ​​Au / CoMoS2(2 / 8) is larger than that of Au / MoS2, indicating that its active sites are more exposed. The addition of cobalt can improve the reactivity of the catalyst. In addition, the binding energies of Au 4f, Mo S 3d, and S2P in Au / CoMoS2(2 / 8) are all lower than those of Au / MoS2, confirming the influence of the strong electronic interactions between Co, Mo, S, and Au on the chemical environment.

[0086] In addition, Table 3 lists the binding energy and peak area data of this series of peaks.

[0087]

[0088] Table 3: XPS data of Au / MoS2 and Au / CoMoS2 (2 / 8);

[0089] In summary, the present invention synthesized cobalt-modified MoS2 via a simple hydrothermal method as a perfect support for Au nanoparticles to prepare a catalytic system with enhanced activity for 4-NP reduction reaction;

[0090] In the present invention, a series of CoMoS2 samples with different Co and Mo molar ratios were prepared by introducing cobalt (Co) as a heteroatom and used to anchor gold nanoparticles. The synthesized Au / CoMoS2 catalysts showed excellent catalytic activity, especially when the molar ratio of Co to Mo was 2:8. Co :M Mo =2:8) showed the best catalytic performance, and its apparent rate constant (k app ) can reach 1.063. The experiment used a series of characterization methods such as XRD, SEM, TEM, Raman spectroscopy, XPS, etc. to analyze the physicochemical properties of the catalyst in detail, and on this basis discussed the promoting effect of cobalt on the catalytic reduction of 4-NP over Au / CoMoS2 catalyst.

[0091] The optimal addition ratio of Co:Mo (mol) is 2:8, and the synthesized Au / CoMoS2 (2 / 8) exhibits the best activity. This experimental process uses a simple method to achieve high performance results. The addition of cobalt effectively improves the catalytic activity. This is because more crystal defects are generated, more edge active sites are exposed, and electron transfer becomes more convenient, thus making the reactive surface properties better.

[0092] This study further explored cobalt (Co)-modified molybdenum disulfide (MoS2)-loaded gold (Au) nanoparticles (Au / Co-MoS2) as a catalyst for the reduction reaction of 4-NP;

[0093] Experimental results show that the introduction of cobalt significantly improves the catalytic activity of the catalyst compared to unmodified Au / MoS2. In particular, the catalyst exhibits optimal catalytic performance when the molar ratio of Co to Mo is 2:8. Catalyst characterization results indicate that the introduction of cobalt increases crystal defects and promotes the exposure of active edge sites, thereby enhancing the catalytic activity of the catalyst surface.

[0094] While the embodiments of the present invention have been shown and described, it will be apparent to those skilled in the art that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a nanocatalyst for the reduction reaction of p-nitrophenol, characterized in that: The specific steps include: S1, CoMoS2 preparation: S101, 1 mmol of a mixture containing ammonium heptamolybdate and cobalt chloride hexahydrate and 30 mmol of thiourea were added to 40 mL of deionized water and magnetically stirred for 30 min; S102, pouring the stirred transparent solution into a stainless steel polytetrafluoroethylene-lined autoclave and heating it at 200°C for 12 hours; S103, the obtained sample was centrifuged and washed with pure water and ethanol, and dried at 80 °C for 8 h to obtain CoMoS2; Preparation of S2, Au / CoMoS2 catalyst: S201, anchoring Au nanoparticles on the support by NaBH4 reduction: Specifically, 40 mg of CoMoS2 was ultrasonically dispersed into 20 mL of a mixed solution of water and ethanol, where the volume ratio of water to ethanol was 18:

2. 5.17 mL of HAuCl4 solution with a molar concentration of 0.01 mol / L was added to the above mixed solution and magnetically stirred for 24 h. 30 mg of NaBH4 was added to the above mixture and magnetically stirred for 1 h. Finally, the product was separated, washed with pure water and ethanol, and dried at 80 °C for 8 h to obtain Au / CoMoS2 nanocomposite material.

2. The method for preparing a nanocatalyst for the reduction reaction of p-nitrophenol according to claim 1, wherein: Including catalytic reaction experiments, the specific steps are as follows: 3 mL of 0.1 mol / L 4-NP solution was added to a quartz cuvette, followed by 0.15 mL of 0.1 mol / L NaBH4 solution. After thorough mixing, 1 mg of Au / CoMoS2 catalyst was added to initiate the catalytic reduction reaction. The progress of the reduction reaction was monitored by monitoring the UV-visible absorption spectrum of 4-NP at different reaction times.

3. The method for preparing a nanocatalyst for the reduction reaction of p-nitrophenol according to claim 2, wherein: The crystal structure of the catalyst was also tested using an X-ray diffractometer under Cu radiation at 40 kV and 30 mA. The specific steps are as follows: First, in 5–90 o The angle range is 5 o The catalyst was scanned at a speed of 100 nm / min, and the morphology was characterized on a field emission scanning electron microscope to observe the catalyst morphology, and the element spectrum was analyzed by an energy dispersive X-ray elemental analysis system. Secondly, X-ray photoelectron spectroscopy was performed on a ThermoFischer ESCALAB Xi+ using an AlK monochromatic light source to obtain elemental information; Subsequently, Raman spectra were measured on a Renishaw Raman microspectrometer; Finally, transmission electron microscopy images were acquired by a Tecnai G2 20 TWIN microscope operated at 200 kV.

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