Method for promoting performance of producing H2O2 by electrocatalytic water oxidation reaction through interface regulation and control

Abstract

The invention discloses a method for promoting the performance of producing hydrogen peroxide (H2O2) by electrocatalytic water oxidation reaction through interface regulation and control, which comprises the following steps: (1) carrying out interface modification on a two-dimensional material MXene (V2CTx, Ti3C2Tx, Nb2CTx and Mo2CTx) with negative charges on the surface, loading a cationic polymer poly (diallyldimethylammonium chloride) (PDDA) on the surface through long-time magnetic stirring, and carrying out magnetic stirring on the surface of the two-dimensional material MXene (V2CTx, Ti3C2Tx, Nb2CTx and Mo2CTx) for a long time; regulating and controlling the types of charges on the surface to obtain the MXene / PDDA modified material with positive charges on the surface; and (2) loading the modified material on carbon paper as an anode, taking a graphite flake as a cathode, taking a mixed solution of potassium carbonate and potassium bicarbonate as an electrolyte, and carrying out electro-catalysis two-electron water oxidation reaction under the conditions of normal temperature, normal pressure and constant input voltage to obtain a high-concentration H2O2 product.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrocatalytic water oxidation, and particularly relates to a method for improving the production efficiency of H2O2 in the electrocatalytic water oxidation reaction through interface regulation means. Background Art

[0002] With the increase in human production and living needs, the unsustainability of traditional fossil fuels and the resulting environmental problems have demanded alternative energy sources and green solutions. As an extremely attractive strong chemical oxidant, H2O2 has received extensive attention worldwide since its first appearance in 1818 and has shown great application advantages in many application fields such as fiber bleaching, disinfection, pollutant degradation, and water treatment. It is predicted that by 2024, the global consumption of H2O2 will reach approximately 6 million tons, and the huge demand has put forward higher requirements for the efficient and mild production of H2O2. Currently, the anthraquinone oxidation method is the mainstream process for producing H2O2, and its output has reached more than 95% of the total global H2O2. This method mainly involves the hydrogenation of anthraquinone, the generation and regeneration of H2O2, the extraction, distillation of H2O2, and subsequent storage, transportation, and dilution processes. Although the product cost and energy consumption of the anthraquinone method are low, the H2O2 output is high, and it is suitable for large-scale production, it involves many side reactions and requires the addition of hydrogen, noble metal catalysts, and organic sacrificial agents, which are costly. Moreover, due to chemical instability, the storage and transportation safety problems of H2O2 are also fatal. For a long time, frequent explosion and fire accidents in H2O2 workshops worldwide have caused huge economic losses and a large number of casualties. Therefore, it is crucial to explore a greener and safer method for producing H2O2. In recent years, the method of electrocatalytic water oxidation for synthesizing H2O2 has gradually attracted the attention of many scholars. Compared with the above-mentioned anthraquinone oxidation method, this method has multiple advantages: (1) using the abundant H2O on the earth as the reaction raw material and renewable electricity as the energy supply, it is green, energy-saving, and economical; (2) having few by-products, mild reaction conditions, usually being able to proceed at normal pressure and room temperature, and being able to get rid of the limitations of large reaction facilities, which can significantly reduce storage and transportation risks; (3) this method can also be applied to oxygen-deficient environments such as plateaus and sewers. Therefore, the synthesis of H2O2 by electrocatalytic water oxidation using this method has great prospects. Summary of the Invention

[0003] In view of the urgent requirements for the efficient, green, and safe production of H2O2, the present invention aims to provide a method for promoting the performance of producing H2O2 in the electrocatalytic water oxidation reaction through interface regulation. The method of the present invention has the advantages of simple equipment, convenient operation, low price, and green energy-saving.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A method for promoting the performance of electrocatalytic water oxidation reaction to produce H2O2 through interface regulation, the method comprising the following steps:

[0006] (1) Interface modification of two-dimensional material Mxene with negatively charged surface by cationic polymer:

[0007] Add a certain amount of Mxene powder material into deionized water to obtain a Mxene dispersion of 0.1mg mL -1 , and add 10 mL of cationic polymer PDDA to 100 mL of the dispersion. Further, load PDDA on the surface of Mxene by long-term magnetic stirring, so as to regulate the type of charge on the surface of Mxene. Then, centrifuge and dry the stirred mixed solution to obtain a positively charged MXene / PDDA modified powder material;

[0008] (2) Electrocatalytic water oxidation of the modified material to produce H2O2:

[0009] Under normal temperature and pressure, load the MXene / PDDA modified material and Mxene material in step (1) on carbon paper as the anode, with a loading area of 1*1cm 2 , use graphite sheet as the cathode, and a mixed solution of 0-3.5M potassium carbonate and 0-0.5M potassium bicarbonate as the electrolyte. Carry out electrocatalytic two-electron water oxidation reaction under the condition of a constant input voltage of 2.2-3.4V vs. RHE, and high-concentration H2O2 products can be obtained.

[0010] Preferably, the Mxene material in step (1) includes V2CT x , Ti3C2T x , Nb2CT x and Mo2CT x .

[0011] Preferably, the mass fraction of the cationic polymer PDDA added in step (1) is 1wt%.

[0012] Preferably, the time of magnetic stirring in step (1) is 24-48h.

[0013] Preferably, the centrifugation speed and time in step (1) are 4000rpm and 60min respectively, and the drying temperature and time are 60°C and 48h.

[0014] Preferably, the anode material loaded on the carbon paper in step (2) includes V2CT x / PDDA, Ti3C2T x / PDDA, Nb2CT x / PDDA, Mo2CTx / PDDA, V2CT x , Ti3C2T x , Nb2CT x and Mo2CT x 。

[0015] Preferably, the loading area of the anode material on the carbon paper in step (2) is 1 * 1 cm 2 。

[0016] Preferably, the reaction cell used for the electrocatalytic reaction in step (2) is an H-type double cell. The Nafion membrane installed in the middle of the cell only allows protons to pass through, and the anode and cathode are located on both sides of the Nafion membrane respectively.

[0017] Preferably, the input voltage of the electrocatalytic reaction in step (2) is 2.2 - 3.4 V vs. RHE, and the time is 30 min.

[0018] Compared with the prior art, the present application has the following advantages:

[0019] (1) Only using the organic matter PDDA as a modifier, through long-term stirring, the charge type on the surface of the MXene material can be changed from negative to positive, and further the performance of H2O2 generation in electrocatalytic water oxidation can be improved. The operation is simple and the cost is low;

[0020] (2) For electrocatalytic water oxidation

[0021] The reaction uses the widely existing H2O as a raw material, a cheap carbon rod as the cathode, and cheap carbonates and bicarbonates as electrolytes, and high-concentration H2O2 can be prepared, which has the advantages of on-site rapid preparation, greenness, and low energy consumption;

[0022] (3) The reaction can occur at normal temperature and pressure, the conditions are mild, the by-products are few, and it can get rid of the limitations of large reaction facilities, and can significantly reduce the storage and transportation hazards of H2O2. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is the X-ray diffraction (XRD) pattern of V2CT x / PDDA and V2CT x ;

[0024] Figure 2 is the Zeta potential pattern of V2CT x / PDDA and V2CT x ;

[0025] Figure 3 is the V2CT x / PDDA and V2CT xLinear sweep voltammetry (LSV) performance graph in the potential range of 1.9 - 3.4 V vs. RHE;

[0026] Figure 4 For V2CT x / PDDA and V2CT x Concentration graph of electrocatalytic water oxidation to produce H2O2 in the potential range of 2.2 - 3.4 V vs. RHE;

[0027] Figure 5 For V2CT x / PDDA and V2CT x Rate graph of electrocatalytic water oxidation to produce H2O2 in the potential range of 2.2 - 3.4 V vs. RHE;

[0028] Figure 6 For V2CT x / PDDA and V2CT x Faraday efficiency graph of electrocatalytic water oxidation to produce H2O2 in the potential range of 2.2 - 3.4 V vs. RHE;

[0029] The realization, functional features, and advantages of the purpose of this application will be further described in conjunction with the embodiments and with reference to the accompanying drawings. Detailed implementation manners

[0030] The following will further describe the present invention in conjunction with the accompanying drawings. It should be noted that the following embodiments are based on this technical solution and give detailed implementation manners and specific operation processes, but the protection scope of the present invention is not limited to this embodiment.

[0031] Embodiment 1

[0032] Perform interfacial modification on V2CT x :

[0033] Step 1: Add 10 mg of V2CT x powder material into 100 mL of deionized water to obtain a 0.1 mg mL -1 V2CT x dispersion, and add 10 mL of 1 wt% cationic polymer PDDA to this dispersion. Further, load PDDA on the surface of V2CT x by magnetic stirring for 24 h, so as to regulate the charge type on the surface of V2CT x . Then, centrifuge the stirred mixed solution at 4000 rpm for 60 min and dry it at 60 °C for 48 h to obtain the V2CT x / PDDA modified powder material with a positive charge on the surface.

[0034] Step 2: Use an X-ray diffractometer and a Zeta potential analyzer to detect the crystal structure and surface Zeta potential of V2CT x / PDDA and V2CT x .

[0035] The results are as Figure 1 , shown in Figure 2, and it can be seen that:

[0036] Compared with V2CT x , the crystal structure of the V2CT x / PDDA modified material does not change significantly, and the crystallinity is very good. However, the surface Zeta potential changes from -49 mV to 13 mV.

[0037] Therefore, this method can successfully prepare V2CT x / PDDA and effectively regulate the charge type at the interface of the V2CT x material.

[0038] Example 2

[0039] Load V2CT x / PDDA and V2CT x onto the carbon paper as the anode material:

[0040] First, weigh 20 mg of the electrode material powder and 15 mg of polyvinylidene fluoride (PVDF), mix them, and then add 200 μL of N-methylpyrrolidone (NMP) solvent. After stirring well for 30 min, a uniform slurry is obtained. Place the carbon paper substrate on a heating plate, use a pipette to coat the slurry on the front of the carbon paper, and then heat it. The heating temperature and time are 150 °C and 7 min, respectively, to obtain the V2CT x / PDDA and V2CT x anode electrode sheet.

[0041] Example 3

[0042] LSV performance of the anode material for electrocatalytic water oxidation:

[0043] Set up an electrochemical reaction system. The electrochemistry is an H-type double cell. The Nafion membrane installed in the middle of the cell only allows protons to pass through. The anode and cathode are located on both sides of the Nafion membrane, respectively. The anode is the V2CT x / PDDA, V2CT x anode electrode sheet, the cathode is a graphite sheet, and the electrolyte is a mixed solution of 3.5 M potassium carbonate and 0.5 M potassium bicarbonate. Subsequently, the LSV performance of the anode material is tested in the potential range of 1.9 - 3.4 V vs. RHE.

[0044] The results are as Figure 3 shown, and it can be seen that:

[0045] V2CT x The LSV performance of V2CT / PDDA is significantly higher than that of V2CT x , V2CT x can reach 50 mA cm at 2.81 vs. RHE -2 , while for V2CT x / PDDA it can be achieved at a lower 2.36 vs. RHE

[0046] Therefore, this method can significantly improve the electrochemical performance of MXene materials

[0047] Example 4

[0048] Performance of the anode material for electrocatalytic water oxidation to produce H2O2:

[0049] Step 1: Set up an electrochemical reaction system. Electrochemistry uses an H-type double cell. The Nafion membrane installed in the middle of the cell only allows protons to pass through. The anode and cathode are located on both sides of the Nafion membrane respectively. The anode is the V2CT x / PDDA, V2CT x electrode sheet, and the cathode is a graphite sheet. The electrolyte is a mixed solution of 3.5 M potassium carbonate and 0.5 M potassium bicarbonate. 20 mL of electrolyte is used on both sides of the Nafion membrane. Subsequently, the electrocatalytic water oxidation reaction is carried out for 30 min in the potential range of 2.2, 2.4, 2.6, 2.8, 3.0, 3.2, and 3.4 V vs. RHE

[0050] Step 2: Use ultraviolet-visible spectrophotometry to detect the H2O2 absorbance of the V2CT x / PDDA and V2CT x anodes, and calculate the corresponding H2O2 production concentration, H2O2 yield, and Faraday efficiency

[0051] The results are as Figures 4 - 6 shown, and it can be seen that:

[0052] V2CT x / PDDA has significantly better performance in producing H2O2 than V2CT x . At 3.2 V vs. RHE, for V2CT x / PDDA, the H2O2 production concentration, rate, and Faraday efficiency reach 55.2 mM, 78.8 μmol min -1 cm -2 and 80% respectively

[0053] Therefore, this method can effectively improve the performance of MXene materials in electrocatalytic water oxidation to produce H2O2

[0054] In summary, it can be seen that the present invention only uses the organic matter PDDA as a modifier, and through long-term stirring, the charge type distribution on the surface of the MXene material can be changed, realizing the improvement of the production performance of H2O2 products in electrocatalytic water oxidation, with the characteristics of simple operation, low cost and green high efficiency, and having great practical application prospects.

[0055] For those skilled in the art, various corresponding changes and deformations can be given according to the above technical solutions and concepts, and all these changes and deformations should be included within the protection scope of the claims of the present invention.

Claims

1. A method for promoting the performance of electrocatalytic water oxidation reaction to produce hydrogen peroxide (H2O2) through interface regulation, the method comprising the following steps: (1) Interface modification of two-dimensional material Mxene with negatively charged surface by cationic polymer: A certain amount of Mxene powder material was added to deionized water to obtain a Mxene dispersion of 0.1 mg mL -1 −1. Then, 10 mL of the cationic polymer poly(diallyldimethylammonium chloride) (PDDA) was added to 100 mL of the dispersion. PDDA was further loaded onto the surface of Mxene by long-term magnetic stirring to regulate the type of charge on the Mxene surface. Then, the stirred mixed solution was centrifuged and dried to obtain a positively charged MXene / PDDA modified powder material; (2) Electrocatalytic water oxidation of the modified material to produce H2O2: Under normal temperature and pressure, both the MXene / PDDA modified material and the Mxene material described in step (1) are loaded on carbon paper as the anode, and the loading area is 1*1 cm 2 , graphite flakes are used as the cathode, and a mixed solution of 0-3.5 M potassium carbonate and 0-0.5 M potassium bicarbonate is used as the electrolyte. The electrocatalytic two-electron water oxidation reaction is carried out under the condition of a constant input voltage of 2.2-3.4 V vs. RHE, and a high-concentration H2O2 product can be obtained.

2. The method for promoting the performance of electrocatalytic water oxidation reaction to produce H2O2 through interface regulation according to claim 1, characterized in that, The Mxene material in the step (1) includes V2CT x , Ti3C2T x , Nb2CT x and Mo2CT x .

3. The method for promoting the performance of electrocatalytic water oxidation reaction to produce H2O2 through interface regulation according to claim 1, characterized in that, The mass fraction of the cationic polymer PDDA added in the step (1) is 1 wt%.

4. The method for promoting the performance of electrocatalytic water oxidation reaction to produce H2O2 through interface regulation according to claim 1, characterized in that The magnetic stirring time in the step (1) is 24 - 48 h.

5. The method for promoting the performance of electrocatalytic water oxidation reaction to produce H2O2 through interface regulation according to claim 1, wherein, The centrifugation speed and time in the step (1) are 4000 rpm and 60 min, and the drying temperature and time are 60 °C and 48 h.

6. The method for promoting the performance of electrocatalytic water oxidation reaction to produce H2O2 through interface regulation according to claim 1, characterized in that, The anode material loaded on the carbon paper in the step (2) includes V2CT x / PDDA, Ti3C2T x / PDDA, Nb2CT x / PDDA, Mo2CT x / PDDA, V2CT x , Ti3C2T x , Nb2CT x and Mo2CT x electrode materials. Among them, 20 mg of the electrode material powder is first mixed with 15 mg of polyvinylidene fluoride (PVDF), then 200 μL of N-methylpyrrolidone (NMP) solvent is added, and after stirring well for 30 min, a uniform slurry is obtained. The carbon paper substrate is placed on a hot plate, and the slurry is applied to the front of the carbon paper using a pipette and then heated. The heating temperature and time are 150 °C and 7 min.

7. The method for promoting the performance of electrocatalytic water oxidation reaction to produce H2O2 through interface regulation according to claim 1, wherein, The loading area of the anode material in step (2) on the carbon paper is 1*1 cm 2 .

8. The method for promoting the performance of electrocatalytic water oxidation reaction to produce H2O2 through interface regulation according to claim 1, characterized in that, The reaction cell used for the electrocatalytic reaction in the step (2) is an H-type double cell, and the Nafion membrane installed in the middle of the cell only allows protons to pass through, and the anode and cathode are located on both sides of the Nafion membrane respectively.

9. The method for promoting the performance of electrocatalytic water oxidation reaction to produce H2O2 through interface regulation according to claim 1, characterized in that, The input voltage of the electrocatalytic reaction in the step (2) is 2.2 - 3.4 V vs. RHE, and the time is 30 min.

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