CN115672357A

CN115672357A - Preparation method and application of plasma modified molybdenum-doped nickel sulfide

Info

Publication number: CN115672357A
Application number: CN202211209717.8A
Authority: CN
Inventors: 沈拥军; 房帅康; 陈银; 周全法; 吴泽颖; 周品; 冯坤; 柏寄荣; 沈海林; 张微
Original assignee: Nantong University; Changzhou Institute of Technology
Current assignee: Nantong University; Changzhou Institute of Technology
Priority date: 2022-09-30
Filing date: 2022-09-30
Publication date: 2023-02-03

Abstract

The invention discloses a preparation method of plasma modified molybdenum doped nickel sulfide, which comprises the following steps of respectively carrying out ultrasonic treatment on nickel foam in hydrochloric acid, ethanol and water in sequence, and then carrying out vacuum drying; mixing Na ₂ MoO ₄ ·2H ₂ Adding O into ultrapure water, stirring and dissolving; thiourea is put into the dissolved solution and stirred to obtain a clear solution; then foaming the nickelThe surface is cleaned and then is immersed into a clear solution, the hydrothermal reaction is carried out after the ultrasonic treatment in water, and the Mo-Ni which grows uniformly is obtained after the cooling to the room temperature ₃ S ₂ /NF-200; then washing the mixture by ultrapure water and ethanol respectively and drying the washed mixture in a vacuum furnace; and finally, transferring the synthesized molybdenum-doped nickel sulfide to the center of a dielectric barrier discharge reactor, and processing under alternating voltage to obtain PA @ Mo-Ni3S2/NF-200. The product electrode of the invention has good nano structure, uniform growth, enhanced charge transmission capability and good effect of degrading orange G dye, and can be used for large-scale hydrogen production by water decomposition and environmental pollution treatment.

Description

Preparation method and application of plasma modified molybdenum-doped nickel sulfide

Technical Field

The invention relates to a plasma modification method, in particular to a preparation method and application of plasma modified molybdenum doped nickel sulfide.

Background

The current fossil fuel resources are gradually decreasing, and the use of fossil fuels also causes significant environmental pollution, so the development of sustainable and environmentally friendly energy is crucial for human survival. Hydrogen has excellent energy density and environmental compatibility, and thus is an ideal solution to the problem of energy in the future. Sustainable hydrogen production can be achieved by electrochemical and photoelectrochemical water splitting because both technologies benefit from abundant water resources and produce high purity H ₂ . Electrochemical water contentThe process can be used to produce clean hydrogen with zero carbon emissions. Platinum (Pt) is the most effective HER electrocatalyst, with zero overpotential and various pH tolerance. However, the scarcity and expense of noble metal-based electrocatalysts has prevented their large-scale application in commercial electrolyzers. Therefore, there is a need to design an active, durable, inexpensive and readily available electrocatalyst to serve as an effective electrode material for HER.

Layered Transition Metal Dihalides (LTMDs), e.g. MoS ₂ 、WS ₂ And Ni ₃ S ₂ Has been studied as a HER catalyst and has been the leading edge of electrocatalysts. For HER in alkaline solution, the kinetics are influenced by the balance between water dissociation and the subsequent chemisorption of water-splitting intermediates. Experimental research and Density Functional Theory (DFT) calculation results show that the uncoordinated Mo-S sites along the edge of the molybdenum disulfide have high chemical adsorption capacity of hydrogen, moS ₂ And Ni ₃ S ₂ The transition metals have excellent HER performance. In the industrial production process, the discharge of a large amount of sewage is inevitable, and particularly, the sewage in the printing and dyeing industry is large in amount and difficult to treat.

Disclosure of Invention

The invention aims to solve the technical problem of providing a preparation method of plasma modified molybdenum-doped nickel sulfide, which can be used for preparing efficient and stable Mo-doped Ni on foamed nickel ₃ S ₂ Electrocatalyst of Mo-doped Ni ₃ S ₂ In the structure, ni is embedded ₃ S ₂ Mo ions in the nano particles form a large number of Mo-S interface parts, are prepared at different temperatures and are subjected to water decomposition, and the water is decomposed to have the best hydrogen analysis effect and is used for treating dye wastewater.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows:

a preparation method of plasma modified molybdenum doped nickel sulfide comprises the following steps:

firstly, sequentially carrying out ultrasonic treatment on nickel foam in hydrochloric acid, ethanol and water respectively, and then carrying out vacuum drying;

step two, na is added ₂ MoO ₄ ·2H ₂ Adding ultra-pure OStirring and dissolving in water;

step three, putting thiourea into the solution dissolved in the step two, and stirring to obtain a clear solution;

step four, immersing the nickel foam surface into a clear solution after cleaning, then carrying out ultrasonic treatment in water, carrying out hydrothermal reaction at 180 ℃, and cooling to room temperature to obtain uniformly grown Mo-Ni ₃ S ₂ /NF-180；

Step five, taking the Mo-Ni out of the solution ₃ S ₂ NF-180, washing with ultrapure water and ethanol for 3 times respectively to remove unreacted residues, and drying in a vacuum furnace;

step six, repeating the step one to the step five, and preparing Mo-Ni at 200 ℃ and 220 ℃ respectively ₃ S ₂ NF-200 and Mo-Ni ₃ S ₂ /NF-220；

And seventhly, shearing part of the molybdenum-doped nickel sulfide synthesized at 200 ℃ and transferring the molybdenum-doped nickel sulfide to the center of the dielectric barrier discharge reactor, and treating under alternating voltage to obtain PA @ Mo-Ni3S2/NF-200.

Preferably, the size of the upper and lower bottom surfaces of the nickel foam is 3cm × 3cm, and the thickness is 2mm.

Preferably, in the first step, the concentration of hydrochloric acid is 3mol/L, the concentration of ethanol is 95%, and the ultrasonic treatment time is 15min.

Preferably, na in the second step ₂ MoO ₄ ·2H ₂ The mass of O was 0.2g, and the volume of ultrapure water was 40mL.

Preferably, the mass of the thiourea in the third step is 0.2g, and the stirring time is 15min.

Preferably, the ultrasonic treatment time in the fourth step is 15min, and the hydrothermal reaction is 16h.

Preferably, the step five is dried in a vacuum furnace at the temperature of 80 ℃ for 8-12h.

Preferably, the alternating voltage in the seventh step is 70V, and the processing time is 60s.

Preferably, the application of the plasma modified molybdenum doped nickel sulfide in degrading orange G wastewater.

Compared with the prior art, the invention has the following beneficial effects:

(1) The invention grows Mo-doped Ni on 3D Ni foam ₃ S ₂ Nanostructured arrays as highly efficient electrocatalysts, PA @ Mo-Ni ₃ S ₂ the/NF-200 electrode has good nano structure, uniform growth and enhanced charge transmission capability, PA @ Mo-Ni ₃ S ₂ The overpotential for hydrogen evolution of the/NF-200 electrode was 114mV.

(2) The invention prepares high-efficiency and stable Mo-doped Ni on foamed nickel ₃ S ₂ Electrocatalyst of Mo-doped Ni ₃ S ₂ In the structure, ni is embedded ₃ S ₂ Mo ions in the nano particles form a large amount of Mo-S interface parts, are prepared at 200 ℃ and are subjected to water decomposition, and the water is decomposed to be used for treating dye wastewater with the best hydrogen decomposition effect, so that the dye wastewater can be treated efficiently.

(3) The plasma of the invention is combined with the catalyst to degrade orange G dye, when the conductivity is 3mS/cm, the voltage is 70V, the initial concentration of the dye is 50mg/L, and the pH value is 3, the degradation rate can reach 83.28 percent, and the stable, cheap and abundant electrocatalyst is suitable for large-scale water decomposition hydrogen production and environmental pollution treatment.

Drawings

FIG. 1 is an XRD pattern of molybdenum doped nickel sulfide synthesized at different temperatures and plasma modified molybdenum doped nickel sulfide;

FIG. 2 XPS spectra of plasma modified molybdenum doped nickel sulfide: (a) PA @ Mo-Ni ₃ S ₂ A full spectrum of NF-200; (b) Mo 3d; (c) Ni 2p; (d) S2 p;

(a-h) are SEM images of molybdenum doped nickel sulfide plasma modified synthesized at 200 ℃; (h-i) PA @ Mo-Ni in selected regions ₃ S ₂ EDS profile of NF-200;

FIG. 4 (a-b) TEM image of plasma modified molybdenum doped nickel sulfide; (c) HRTEM of plasma modified molybdenum doped nickel sulfide; (d) Plasma modified molybdenum doped nickel sulfide selective area electron diffraction patterns; (e-i) elemental mapping of the plasma modified molybdenum doped nickel sulfide;

FIG. 5 electrochemical HER Properties of electrocatalyst in 1.0M Potassium hydroxide solution (a) Scan Rate 5mV s ^-1 Polarization curve over time (iR correction); (b) 10mA cm ^-2 Overpotential corresponding to current density; (c) Tafel spectra corresponding to each catalyst; (d) Electrochemical Impedance Spectroscopy (EIS) of various catalysts; polarization plots (inset) after initial and 1000 cycles of CV cycling;

FIG. 6 is a graph comparing the predicted value and the actual value of plasma degradation orange G;

FIG. 7 Effect of initial concentration and pH interaction on orange G degradation Rate in combination: a contour map; a response surface;

FIG. 8. Effect of initial concentration and voltage interaction on orange G degradation rate in combination: a contour map; a response surface;

FIG. 9. Effect of interaction of initial concentration and conductivity on orange G degradation Rate in combination: a contour map; a response surface;

FIG. 10. Effect of the interaction of pH and voltage of solutions under the combined system on the rate of orange G degradation: a contour map; a response surface;

FIG. 11. Effect of the interaction of pH and conductivity of solutions on orange G degradation Rate in combination: a contour map; a response surface;

FIG. 12. Effect of the interaction between voltage and conductivity on the rate of orange G degradation under the combined system: a contour map; a responsive surface.

Detailed Description

1. Experimental part

1. Experimental reagents and instruments

TABLE 1 Experimental reagents

TABLE 2 Experimental instruments

2. Sample characterization test

XRD patterns were obtained on a Bruker D8 Advance X-ray diffractometer with Cu ka radiation. SEM images and EDS spectra were recorded with a Zeiss Gemini 300 microscope. High resolution TEM and mapping analysis were performed using a JEOL JEM 2100F microscope. XPS spectra were obtained on a Thermo Kalpha photoelectron spectrometer.

3. Method for producing a material

cutting nickel foam with the thickness of 2mm to obtain upper and lower bottom surfaces of 3cm multiplied by 3cm, respectively carrying out ultrasonic treatment for 15min in hydrochloric acid with the concentration of 3mol/L, ethanol with the concentration of 95% and water in sequence, and then carrying out vacuum drying;

step two 0.2g of Na ₂ MoO ₄ ·2H ₂ Adding O into 40mL of ultrapure water, stirring and dissolving;

step three, 0.2g of thiourea is put into the solution dissolved in the step two, and is stirred for 15min to obtain a clear solution;

step four, immersing the nickel foam into a clear solution after the surface of the nickel foam is cleaned, then carrying out ultrasonic treatment for 15min in water, carrying out hydrothermal reaction for 16h at 180 ℃, and cooling to room temperature to obtain uniformly grown Mo-Ni ₃ S ₂ /NF-180；

Step five, taking Mo-Ni out of the solution ₃ S ₂ NF-180, washing with ultrapure water and ethanol for 3 times respectively to remove unreacted residues, and drying in a vacuum furnace for 10h;

Seventhly, shearing 1cm multiplied by 1cm of molybdenum-doped nickel sulfide synthesized at the temperature of 200 ℃, transferring the molybdenum-doped nickel sulfide to the center of a dielectric barrier discharge reactor, and treating for 60S under the alternating voltage of 70V to obtain PA @ Mo-Ni3S2/NF-200.

The plasma modified molybdenum-doped nickel sulfide is suitable for degrading orange G wastewater.

4. Electrochemical testing

Tested in 1M KOH by a three-electrode system, the catalyst-loaded NF served as the working electrode, the counter electrode and the reference electrodeThe specific electrodes are graphite rods and Ag/AgCl electrodes respectively. All initial data were calibrated using 85% ir offset and the potential of the Reversible Hydrogen Electrode (RHE) was calculated using the following formula: e (vs. RHE) = E (vs. Ag/AgCl) +0.197+0.059 × pH. Linear Sweep Voltammetry (LSV) and Cyclic Voltammetry (CV) were used to determine the activity of the catalyst on HER, respectively. Before recording, at 100mV s ^-1 Scanning until a stable cyclic voltammogram is obtained. At 5mV s ^-1 Linear sweep voltammograms were recorded and the Tafel slope was obtained by plotting the overpotential pair log (J) from the LSV curve. Electrochemical Impedance Spectroscopy (EIS) in the frequency range of 0.01 to 10 ⁵ Recorded in Hz.

5. Response surface catalytic degradation dye

Adopting Box-Behnken design (BBD) to combine catalyst PA @ Mo-Ni with DBD ₃ S ₂ the/NF-200 degradation process of orange G was analyzed by using the decolorization ratio of orange G as a response value, denoted as Y, and concentration, pH, voltage and conductivity as action factors, denoted as A, B, C and D, respectively (Table 3). 29 groups of interactive experiments are designed, the influence of four factors on orange G degradation is examined, and the optimal process conditions are determined.

TABLE 3 values and horizontal ranges of the factors

2. Characterization and Performance analysis of the catalyst

1. XRD analysis

Nickel foam is the substrate of choice due to its 3D macroporous structure, excellent conductivity and various electrochemical properties that are advantageous for the intended application. First, ultrapure water, sodium molybdate, thiourea and clean nickel foam were placed in a stainless steel autoclave. The autoclave was run at different temperatures of 180 ℃,200 ℃ and 220 ℃ for 16 hours. During the reaction, na ₂ MoO ₄ Is reduced, ni is oxidized by thiourea, and plasma modified Mo-doped Ni is formed after electric shock of plasma ₃ S ₂ And (4) array. Nickel foam not only acts as a nickel source, but also as an anchoring PA @ Mo-Ni ₃ S ₂ /NF-200 matrix. The resulting foamed nickel surface was all black, indicating that the plasma modified Mo-doped Ni was uniformly formed ₃ S ₂ And (3) array. Figure 1 shows the X-ray diffraction (XRD) patterns of electrocatalysts prepared under various conditions. In fig. 1, the diffraction peaks are evident for Ni except at 44.3 °,51.6 ° and 76.2 °. A peak of 21.5 ° may be assigned to the (101) plane, a peak of 30.9 ° to the (110) plane, a peak of 38.0 ° to the (003) plane, a peak of 49.5 ° to the (113) plane, a peak of 50.0 ° to the (211) plane, a peak of 55.0 ° to the (122) plane, and a peak of 56.3 ° to the (300) plane. Although these peaks confirmed Ni ₃ S ₂ But the diffraction peak of the molybdenum compound is not significant, because it may be due to partial doping of Mo to Ni ₃ S ₂ In the lattice, they are masked by the Ni diffraction peak, as observed in other metal-doped catalysts.

2. XPS analysis

X-ray photoelectron spectroscopy (XPS) measurements (fig. 2) were performed to identify the major constituent elements and characterize the chemical valence states of these elements. Selection of PA @ Mo-Ni ₃ S ₂ the/NF-200 is used as a target sample because it has a series of better electrochemical performances as an electrocatalyst. In addition to the C1S and O1S peaks, the Ni 2p, mo 3d and S2 p peaks, PA @ Mo-Ni, are clearly observed ₃ S ₂ the/NF-200 sample clearly showed the presence of Ni, mo, S, C, O elements (FIG. 2 a). FIGS. 2b-d are Mo 3d, ni 2p and S2 p high resolution X-ray photoelectron spectra of the samples. FIG. 2b shows PA @ Mo-Ni ₃ S ₂ Typical Mo 3d fitting peaks for/NF-200, mo 3d at 234.7 and 231.6eV _3/2 And Mo 3d _5/2 Peak indicates PA @ Mo-Ni ₃ S ₂ Characteristic Mo in/NF-200 ⁴⁺ And (4) doping. Ni doped with Mo ₃ S ₂ Containing pure Ni ₃ S ₂ Missing Mo in the sample ⁴⁺ Peak of (2). This indicates that Mo is mainly Mo ⁴⁺ Form of (2) is doped in Ni ₃ S ₂ In (1). Furthermore, the lower the binding energy, meaning the lower the valence of Mo, for PA @ Mo-Ni ₃ S ₂ This is advantageous for NF-200 to enhance HER performance under alkaline conditions. As shown in FIG. 2c, two strong peaks at 872.8 and 855.2eV are included, forCorresponding to Ni 2p _1/2 And Ni 2p _3/2 The binding energy of (2), the peak indicates Ni precisely ₃ S ₂ Ni in (1) ³⁺ And Ni ²⁺ In the oxidized state. Two other satellite peaks were also observed, two broad peaks at 878.9 and 860.9eV coinciding with the satellite peaks, corresponding to the vibroseis-type peaks of Ni. FIG. 2d shows that the two peaks at 160.9eV and 162.2eV belong to S2 p, respectively _3/2 And S2 p _1/2 The peak at 168.0eV is due to oxidation in air to produce sulfate. All results of the study showed that Ni ₃ S ₂ And Mo ⁴⁺ There is a strong electronic interaction between them, and a coupling interface is established.

3. SEM analysis

FIG. 3 shows PA @ Mo-Ni prepared with a nickel foam support ₃ S ₂ SEM image and EDS map of/NF-200 catalyst. PA @ Mo-Ni formed after plasma modification at 200 DEG C ₃ S ₂ SEM images of/NF-200 samples illustrate the specific morphology of the post-synthesis samples. In the 3D skeleton of the nickel foam shown in fig. 3a it can be seen that the originally smooth nickel foam surface becomes rough and a dense hemp blank grows on top (fig. 3 b-c). Upon further magnification, it was found that the rough structure is actually formed by numerous tiny nanorods piled together to form a nano forest (fig. 3 d-g), the nanorods are uniformly agglomerated together and attached to the surface of the nickel foam, and the entire surface of the Ni substrate is uniformly and densely covered. During the reaction process, the porous three-dimensional (3D) Ni foam carrier not only serves as anchoring PA @ Mo-Ni ₃ S ₂ Conductive network of/NF-200, and for forming high-density branching-like PA @ Mo-Ni ₃ S ₂ the/NF-200 nano-carrier provides a source of Ni. Furthermore, the morphology of these catalysts is subject to MoO due to the anisotropic growth characteristics of molybdate anions ₄ ^2- A significant effect of (a). Therefore, it does not contain Na ₂ MoO ₄ Prepared pure Ni ₃ S ₂ The catalyst is uniform nano-sheets instead of dendritic nano-rods growing on the surface of the Ni foam. Dendritic PA @ Mo-Ni ₃ S ₂ the/NF-200 nanorods exhibit 3D anisotropy, which connects to form a nano forest. FIG. 3h-i is a selection areaThe EDS spectrum of (a) confirms the presence of Mo, ni and S elements in the vulcanizate.

4. TEM analysis

The prepared PA @ Mo-Ni is further discussed by adopting two methods of a transmission electron microscope and a high-resolution transmission electron microscope (HRTEM) ₃ S ₂ Detailed morphology and crystal structure of/NF-200. Their individual structures are good, forming nanorod structures. As shown in FIGS. 4a-b, PA @ Mo-Ni in dendritic form ₃ S ₂ the/NF-200 nano rods have uniform diameter. In contrast, pure Ni ₃ S ₂ The shape of the nano-film is similar to that of a thick nano-sheet with a smooth surface, and shows that Mo cation induces dendritic Mo to dope Ni ₃ S ₂ Important role in the formation of nano-forests. It is noted that in Ni ₃ S ₂ Has remarkable lattice spacing after being doped with Mo, and can pass through PA @ Mo-Ni ₃ S ₂ HRTEM image of/NF-200 confirmed that the lattice spacing of (110) plane was 0.29nm, that of (003) plane was 0.24nm, and that of (113) plane was 0.18nm (FIG. 4 c). Furthermore, a single PA @ Mo-Ni ₃ S ₂ The Selected Area Electron Diffraction (SAED) mode of the/NF-200 nanorod shows PA @ Mo-Ni ₃ S ₂ The polycrystalline structure of/NF-200 has a cyclic polycrystalline structure (FIG. 4 d), with pure Ni ₃ S ₂ And (4) the same. This further confirms that Mo was successfully doped with Ni by doping ₃ S ₂ In (1). Elemental mapping analysis (FIGS. 4 e-i) by energy dispersive X-ray spectroscopy in combination with Transmission Electron microscopy (STEM-EDS) clearly shows that the Mo, ni and S elements are in Mo-doped Ni ₃ S ₂ The distribution in the sample is uniform.

5. Catalytic properties of HER

The HER activity of the electrocatalyst was evaluated in alkaline solution (1M KOH) using a standard three-electrode system (fig. 5), and the effect of temperature and plasma modification on the hydrogen evolution reaction after addition of the Mo source was investigated. Mo-Ni was tested under the same conditions ₃ S ₂ /NF-180、Mo-Ni ₃ S ₂ /NF-200、Mo-Ni ₃ S ₂ /NF-220、PA@Mo-Ni ₃ S ₂ HER activity of NF-200. In addition, a current density of 10mA cm was analyzed ^-2 Tafel slope of time (log j-eta)) And overpotential, electrochemical Impedance Spectroscopy (EIS) to estimate and compare the HER performance of the electrocatalyst. As shown in FIG. 5a, PA @ Mo-Ni ₃ S ₂ the/NF-200 has a small over potential of 114mV, which can reach 10mA cm ^-2 Current density of (2) and corresponding Tafel slope of 134mV dec ^-1 . FIG. 5b shows the overpotential Mo-Ni for other electrocatalysts ₃ S ₂ /NF-180，Mo-Ni ₃ S ₂ NF-200 and Mo-Ni ₃ S ₂ the/NF-220 (309, 267 and 145 mV) is relatively high compared to it. Fig. 5c shows the Tafel slope for other electrocatalysts as follows: for Mo-Ni ₃ S ₂ /NF-180，Mo-Ni ₃ S ₂ /NF-200，Mo-Ni ₃ S ₂ NF-220 of 243, 227 and 147mV dec respectively ^-1 . We apply PA @ Mo-Ni ₃ S ₂ The excellent activity of the/NF-200 is attributed to the in situ growth of the electrocatalyst on the nickel foam without any binder. This method, in addition to allowing uniform growth, also enhances the mechanical adhesion and electrical conductivity of the catalyst, placing it on a larger electrochemical surface area and a large number of active sites available for electrochemical redox reactions. Ion and transport resistance are also important factors affecting HER response in electrolytes, and to determine the role impedance plays in HER, we recorded a Nyquist plot (fig. 5 d). The ionic and charge transfer resistance values of the HER catalyst in 1M KOH electrolyte were obtained, which enabled us to explain the reaction kinetics of the catalyst. PA @ Mo-Ni ₃ S ₂ The charge transfer resistance of/NF-200 was 1.395. OMEGA, while that of Mo-Ni ₃ S ₂ /NF-180，Mo-Ni ₃ S ₂ NF-200 and Mo-Ni ₃ S ₂ The values of/NF-220 are slightly higher (4.477, 3.41 and 2.224. Omega.). The resistance obtained from EIS spectra of various catalysts indicates PA @ Mo-Ni ₃ S ₂ The impedance of/NF-200 is significantly lower, and therefore the HER kinetics are significantly improved. And after 1000 cycles, the original catalytic performance can still be maintained.

6. Orange G degradation system by response surface method

(1) Model building

Design-Expert software is utilized, 29 groups of experimental schemes are designed by adopting BBD, and DBD-PA @ Mo-Ni is subjected to ₃ S ₂ The response surface design is carried out in the process of degrading orange G by the NF-200, and the degradation time is set as 180s. And experiments were performed according to each set of process conditions and the degradation rate of each set of degradation experiments was calculated, the results are shown in table 4.

From the results in Table 4, the empirical relationship between the response (Y-degradation rate) and the independent variables (A-concentration, B-pH, C-voltage, D-conductivity) gives the following second order polynomial equation:

Y＝58.27-6.23A+0.45B+4.98C-2.05D+2.49AB-1.54AC+2.67AD+0.97BC+0.79BD-0.52CD+4.55A ² +14.05B ² +1.08C ² +2.95D ²

table 4 design of the experimental protocol

(2) Analysis of variance

As shown in fig. 6, the experimental value data are relatively dispersed, but are uniformly distributed in the left and right range regions of a straight line, which indicates that the experimental value is relatively close to the theoretical value, and the two values have relatively high correlation, and thus it is proved that the experimental design idea is correct, and some experimental operation errors exist, but within a controllable range. Table 5 is an analysis of variance table of the degradation rate of orange G wastewater. Combined PA @ Mo-Ni by plasma ₃ S ₂ When the/NF-200 degrades orange G wastewater, the effects of the four factors of initial concentration, initial pH value, voltage and conductivity on the reaction alone, the interaction of the combination of the four factors in pairs on the reaction and the influence of the quadratic power of the four factors on the orange G degradation rate are examined. In the model established by the response surface method, the experimental effect is required to be effective, and it must be explained that the effect of the established response surface model is obvious, and the data table directly indicates that the P value is less than 0.0001 and the F value is larger, the better. Comparing F values of A, B, C and D to obtain A>C>D>B, showing the influence of single factor on the degradation effect of orange G wastewaterThe initial concentration is obtained from the degree of sound>Voltage of>Electrical conductivity>And (4) pH value. The F value of the mismatching term of the model is 1.21, the mismatching probability of the model is 46.15 percent, and the mismatching term is not significant, which indicates that the model is available. In addition, as can be seen from the data table, the P values of a and C in the first term are both less than 0.0001, which shows that the two factors of initial concentration and voltage have very significant influence on the degradation effect of orange G wastewater, and the P value of AD is the smallest of the two factors, which proves that the interaction between the initial concentration and conductivity has a good degradation effect on orange G wastewater, while the P values of other interactions have a large influence. The model is available through data analysis, and the degradation effect of the response surface model on orange G wastewater under the action of pairwise interaction factors can be really seen.

TABLE 5 ANOVA TABLE

(3) Plasma DBD combined with PA @ Mo-Ni ₃ S ₂ Interaction analysis of/NF-200 degradation of orange G

1) Interaction between concentration and pH of solution

FIG. 7 shows the interaction between the solution concentration and the initial pH during the orange G wastewater degradation reaction. The change of the two in the experiment has a remarkable influence on the degradation rate of orange G, which is obtained from the change trend of the contour lines in the graph, and the interaction of the two on the treatment of the orange G wastewater is remarkable, and the P value of AB is the second smallest value in the interaction, so that the conclusion illustrated in the contour line graph is verified. According to the high and low conditions of the three-dimensional graph, the highest removal rate can occur above one of the four critical points, and the optimal degradation effect is obtained at low concentration and acidic pH value. Because the concentration of the dye is low, dye molecules can be fully adsorbed by the catalyst, and the acid environment beneficial to catalysis is provided, and the plasma can be better combined with the acid environment so as to achieve the optimal degradation effect. Therefore, the treatment effect on the orange G wastewater can be improved by keeping the initial concentration lower and reducing the pH value in the experiment, and the optimal orange G wastewater removal rate can be obtained.

2) Interaction between solution concentration and voltage

FIG. 8 shows the interaction between solution concentration and voltage during the degradation reaction of orange G wastewater. Observing a contour diagram, the contour value has small variation span, the P value of the initial concentration and the voltage of the solution is slightly larger than 0.3228, and the interaction between the two influencing factors is not particularly remarkable in the experiment. As can be seen from the contour plot, the contour values are substantially bluish low, indicating a lower removal rate for this portion. In addition, it can be seen from the three-dimensional perspective view that the lower the concentration, the higher the voltage, the higher the degradation rate, wherein the voltage is in the range of 82V upwards, which is obvious. Therefore, the orange G wastewater can obtain the optimal degradation rate in the range when the initial pH =7, the initial concentration of the solution is 50mg/L, the conductivity is 3mS/cm, and the voltage is greater than or equal to 82V.

3) Interaction between concentration and conductivity of a solution

FIG. 9 shows the interaction between both initial concentration and conductivity of the solution during the orange G wastewater degradation reaction. According to the change trend of the contour lines, the following is obviously seen by contrasting the three-dimensional stereogram: the lower the initial concentration is, the smaller the solution conductivity is, and the better the degradation efficiency of the orange G wastewater is; the reason is that when the concentration is low, the number of dye molecules is small, the dye molecules are more easily degraded by the combination of the plasma and the catalyst, the low conductivity can enable the free radicals generated by the plasma to rapidly move and be utilized by the catalyst, and conversely, the high conductivity can enable the free radical molecules to rapidly move in the solution and be not successfully combined with the catalyst, so that the degradation rate is low. Therefore, it can be concluded that under the conditions of a voltage of 70V and an initial pH value of 7, when the initial concentration is 50mg/L and the solution conductivity is 1mS/cm, better orange G wastewater degradation efficiency can be obtained.

4) Interaction between pH and voltage of solution

FIG. 10 shows the extent of the interaction between pH and voltage in the experiment. From the contour map, it can be seen that the contour lines are almost semi-elliptical in shape, and the radian is large, and the interaction of the influencing factors is significant. More active substances such as free radicals can be generated under high voltage, and the catalyst can better utilize the active substances under proper alkaline conditions, so that the degradation is better carried out, and the three-dimensional perspective view shows that: the highest area of the stereogram is positioned at two sides, and the contour map is contrasted, so that the part is positioned at the rightmost upper corner and is slightly orange red in color, and the degradation effect is better. Therefore, under the conditions that the initial concentration is 125mg/L and the conductivity =3mS/cm, when the pH value is 11 and the voltage is 90V, the better orange G wastewater degradation efficiency under the influence factor condition can be obtained.

5) Interaction between pH and conductivity of a solution

Fig. 11 reflects the interaction of pH and conductivity during orange G wastewater treatment, with a P value of 0.6090 indicating that these two factors are not particularly significant, and from the contour plot, the degree of effect of these two factors on the experiment is symmetrical about pH = 7; in the whole contour diagram, a red area hardly appears, and it can be seen that the overall degradation efficiency is not high under the interaction of the two factors. Then, the following three-dimensional perspective views are shown: along with the change of pH and conductivity from low to high, the degradation rate of the orange G wastewater also fluctuates. At higher pH and low conductivity, relatively high degradation rates are obtained. Therefore, in order to increase the degradation rate of the orange G wastewater, the pH value should be properly controlled to be about 11 under the condition that the solution conductivity is low. The removal rate of the orange G wastewater is relatively high when the initial concentration is 125mg/L, the voltage is 70V, the pH value is about 11, and the conductivity is 1 mS/cm.

6) Interaction effects between voltage and conductivity

Fig. 12 reflects the interaction effect of voltage and conductivity in the orange G wastewater treatment process, the P value of both voltage and conductivity is 0.7360, the value is large, the effect is not significant, and the gentle trend of the three-dimensional stereogram can also indicate that the interaction effect of the factor is not particularly significant. As can be seen from fig. 12, the two factors of voltage and conductivity affect the experiment to a similar extent, and the relative effects are not obvious. At high voltages, the lower conductivity has a higher degradation rate. Will be known from the three-dimensional perspective: under the conditions of an initial concentration of 125mg/L and a pH value of 7, a voltage of 90V and a conductivity of 1mS/cm, the degradation rate of the orange G wastewater is relatively high. Therefore, under the condition of certain conductivity, increasing the voltage by a proper amount can improve the treatment effect of the orange G wastewater, but the voltage is not too high, so that the energy consumption is reduced.

The invention discloses the growth of Mo-doped Ni on 3D Ni foam ₃ S ₂ The nano-structure array is used as an efficient electrocatalyst, and Mo-doped Ni modified by plasma is analyzed ₃ S ₂ Morphology, composition and performance of the catalyst. PA @ Mo-Ni ₃ S ₂ the/NF-200 electrode has good nano structure, uniform growth and enhanced charge transmission capability, PA @ Mo-Ni ₃ S ₂ The hydrogen evolution overpotential of the/NF-200 electrode was 114mV. The plasma is combined with the catalyst to degrade orange G dye, four influence factors selected in the experiment are analyzed by using a response surface method, a quadratic polynomial model established by taking the removal rate as a response value has high significance, and the variance analysis of a fitting equation shows that the four single factors have influence sequence on the degradation effect of orange G wastewater: initial concentration>Voltage of>Electrical conductivity of>The pH value; when influencing factors interact, the interaction of the initial concentration and the conductivity has a certain remarkable effect, the interaction of the initial concentration and the pH value is more remarkable, other influencing factors are not remarkable, and the degradation effect of the whole dye is good. Comprehensively, the optimal conditions are that when the conductivity is 3mS/cm, the voltage is 70V, the initial concentration of the dye is 50mg/L, and the pH value is 3, the degradation rate can reach 83.28 percent. The stable, cheap and abundant electrocatalyst produced by the invention is suitable for large-scale hydrogen production by water decomposition and environmental pollution treatment.

Claims

1. A preparation method of plasma modified molybdenum doped nickel sulfide is characterized by comprising the following steps:

firstly, sequentially carrying out ultrasonic treatment on nickel foam in hydrochloric acid, ethanol and water for 12-18min respectively, and then carrying out vacuum drying;

step two, adding Na ₂ MoO ₄ ·2H ₂ Adding O into ultrapure water, stirring and dissolving;

step three, putting thiourea into the solution dissolved in the step two, and stirring for 12-18min to obtain a clear solution;

step four, immersing the nickel foam after surface cleaning into a clear solution, carrying out ultrasonic treatment for 12-18min in water, carrying out hydrothermal reaction for 14-18h at 180 ℃, and cooling to room temperature to obtain uniformly grown Mo-Ni ₃ S ₂ /NF-180；

And seventhly, shearing part of the molybdenum-doped nickel sulfide synthesized at 200 ℃ and transferring the molybdenum-doped nickel sulfide to the center of the dielectric barrier discharge reactor, and treating the molybdenum-doped nickel sulfide for 50-70 seconds under alternating voltage to obtain PA @ Mo-Ni3S2/NF-200.

2. The method of claim 1, wherein the nickel foam has a top and bottom surface size of 3cm x 3cm and a thickness of 2mm.

3. The method for preparing the plasma modified molybdenum-doped nickel sulfide as claimed in claim 1, wherein the hydrochloric acid concentration in the first step is 3mol/L, and the ethanol concentration in the first step is 95%.

4. The method for preparing the plasma modified molybdenum-doped nickel sulfide as claimed in claim 1, wherein Na is added in the second step ₂ MoO ₄ ·2H ₂ The mass of O was 0.2g, and the volume of ultrapure water was 40mL.

5. The method for preparing the plasma modified molybdenum-doped nickel sulfide as claimed in claim 1, wherein the mass of thiourea in the third step is 0.2g.

6. The method for preparing the plasma modified molybdenum-doped nickel sulfide as claimed in claim 1, wherein the temperature in the step five vacuum furnace is 80 ℃.

7. The method for preparing plasma modified molybdenum-doped nickel sulfide as claimed in claim 1, wherein the size of the upper and lower bottom surfaces of molybdenum-doped nickel sulfide sheared in step seven is 1cm x 1cm.

8. The method for preparing nickel sulfide doped with molybdenum according to claim 1, wherein the alternating voltage in the seventh step is 70V.

9. Use of the plasma modified molybdenum doped nickel sulfide of claim 1 in degrading orange G wastewater.