Composite quantum dot electrode material and preparation method and application thereof

Abstract

The invention discloses a composite quantum dot electrode material and a preparation method and application thereof, and belongs to the technical field of photoelectrochemical electrode materials.The preparation method comprises the following steps that after a titanium-based material is polished and cleaned, the titanium-based material is soaked in a first acid solution to remove an oxidation film, and then the titanium-based material is placed in a second acid solution to prepare a titanium substrate; the method comprises the following steps: dissolving a molybdenum source in water, adjusting the pH value, adding a sulfur source, and carrying out a thermal reaction to obtain MoS2 (at) QDs; moS2 (at) QDs, antimony salt and rare earth metal salt are mixed according to a preset proportion and dissolved in an alcoholic solution of concentrated acid to prepare steeping liquor; cleaning and drying a titanium substrate, completely immersing the titanium substrate in the impregnation liquid, and performing a series of treatment to obtain the composite quantum dot electrode material; the prepared electrode material has the advantages of being high in conductivity, high in electrocatalytic activity, excellent in corrosion resistance, lasting in stability and the like, and can be used for oil displacement of oil field polymers.

Description

Technical Field

[0001] The present invention relates to the technical field of photoelectrochemical electrode materials, and in particular to a composite quantum dot electrode material and a preparation method and application thereof. Background Art

[0002] The key to electrochemical preparation of nanobubbles is the electrode material. Traditional electrode materials have problems such as insufficient strength, high price, limited mass transfer, and high energy consumption, which limit the large-scale application of electrochemical preparation of nanobubbles in oil fields. Therefore, the development of an electrode material with high strength, good mass transfer efficiency, moderate cost, and low energy consumption is of great significance for improving the industrial application of electrochemical nanobubble preparation, and also provides necessary support for the combination of oilfield wastewater treatment and polymer flooding technology. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a composite quantum dot electrode material and a preparation method and application thereof. The preparation method has a clear process, simple process control, and the obtained material has a uniform structure and stable performance. The composite quantum dot electrode material has the characteristics of strong conductivity, high electrocatalytic activity, good corrosion resistance, and long-lasting stability. It is suitable for actual application scenarios such as oilfield wastewater treatment and polymer flooding, and has broad market application prospects.

[0004] In order to solve the above technical problems, the present invention is implemented by adopting the following technical solutions: In a first aspect, the present invention provides a method for preparing a composite quantum dot electrode material, comprising the following steps: Step S1: grinding and washing the titanium-based material, ultrasonically cleaning the titanium-based material with acetone, rinsing the titanium-based material with distilled water to remove the acetone, and immersing the titanium-based material in a first acidic solution to remove the oxide film, and then immersing the titanium-based material in a second oxalic acid solution to obtain a titanium matrix; Specifically, when the titanium-based material is subjected to surface treatment, mechanical grinding is used to remove the rough layer and impurities on the surface; the material is placed in clean water for thorough washing to remove the grinding chips and residues generated during the grinding process; then the titanium-based material is immersed in acetone for ultrasonic cleaning to remove organic pollutants on the surface, and after the ultrasonic cleaning is completed, the titanium-based material is rinsed multiple times with distilled water to ensure that the acetone residue is completely removed; then the titanium-based material is placed in a pre-prepared first acidic solution for pickling treatment to remove the oxide film on the surface, and then the titanium-based material is immersed in a second acidic solution for storage to obtain a spare titanium matrix.

[0005] Step S2: Dissolve the molybdenum source in water and adjust the pH value to 5 - 7 with a pH regulator. Add the sulfur source according to a preset ratio, fully dissolve and mix them, then transfer to a reaction kettle and conduct a thermal reaction at 120 - 200 °C for 24 - 48 h. After the reaction, filter, centrifuge, dialyze, and freeze-dry the obtained reaction solution to prepare MoS2@QDs; Specifically, dissolve the molybdenum source in water, precisely adjust the pH value of the solution to an appropriate range with a proper acid-base pH regulator, slowly add the sulfur source according to a preset ratio to ensure its full dissolution and uniform mixing with the molybdenum source. Transfer this mixed solution to a reaction kettle, seal it, and place it in an oven for a high-temperature solvothermal reaction under the preset temperature and time conditions. After the reaction is completed, let it cool naturally. Then, subject the obtained reaction solution to subsequent treatments such as filtration for impurity removal, centrifugation for separation, dialysis for purification, and freeze-drying to finally obtain pure MoS2@QDs for standby.

[0006] Step S3: Mix the prepared MoS2@QDs, antimonide salt, and rare earth metal salt according to a preset ratio and dissolve them in an alcohol solution of concentrated acid to prepare an impregnating solution; Specifically, mix the MoS2@QDs, antimonide salt, and rare earth metal salt according to a preset ratio and dissolve them in a pre-prepared alcohol solution of concentrated acid, and stir well to ensure complete dissolution, thus preparing a uniform impregnating solution; Step S4: Clean the titanium substrate, dry it at 60 - 120 °C, then completely immerse it in the impregnating solution. After impregnation, place it in an oven to dry, then place it in a muffle furnace for calcination. Repeat the processes of impregnation, drying, and calcination multiple times, then let it cool naturally, wash it with distilled water and dry it to prepare a composite quantum dot electrode material.

[0007] Specifically, clean and dry the titanium substrate saved in Step S1, then carefully immerse it in this impregnating solution to ensure that the titanium substrate is completely covered by the impregnating solution. After impregnation, gently take out the substrate material and use a hair dryer to gently blow off the excess impregnating solution on the surface to avoid solution residue affecting the subsequent treatment effect. Then, place the treated titanium substrate in an oven and dry it evenly at a preset temperature. The drying temperature can be 125 - 135 °C, and the time can be 5 - 20 min to remove the residual solvent. After drying is completed, transfer the titanium substrate to a muffle furnace and conduct precise calcination at a high temperature. The calcination temperature can be 250 - 300 °C, and the calcination time can be 5 - 20 min to achieve the structural optimization and performance improvement of the material.

[0008] To ensure the uniformity and high quality of the titanium substrate, the above-mentioned impregnation, drying, and calcination are repeated multiple times, which can be repeated 8 - 10 times. Finally, the titanium substrate that has been processed multiple times is naturally cooled to room temperature, and the last calcination time can be 1 - 2 h. After taking it out, it is thoroughly washed with distilled water to remove surface impurities and residues. After the washing is completed, it is dried again to ensure that the material is completely dry. Finally, the prepared composite quantum dot electrode material is properly stored in a vacuum desiccator for subsequent use.

[0009] In some embodiments, the mesh number of the sandpaper used for polishing the titanium-based material is 120 - 500; the ultrasonic cleaning time with acetone is 20 - 40 min; the acidic solution is an oxalic acid solution with a concentration of 1% - 10%; the soaking time of the titanium-based material in the acidic solution is 1 - 3 h.

[0010] In some embodiments, the molybdenum source is one or both of ammonium molybdate and sodium molybdate; the sulfur source is one or more of sodium sulfide, L-cysteine, and glutathione; the molar ratio of the molybdenum source to the sulfur source is Mo∶S = 1∶(2 - 4).

[0011] In some embodiments, the pH regulator uses a hydrochloric acid solution HCl with a concentration of 0.1% - 1% or ammonia water with a concentration of 0.1% - 1%.

[0012] In some embodiments, the rare earth element Re of the rare earth metal salt is selected from one or more of 17 chemical elements including scandium, yttrium, and lanthanide elements.

[0013] In some embodiments, the molar ratio of Mo:Sb:Re in the MoS2@QDs, antimony salt, and rare earth metal salt is (2 - 5):1:(0.1 - 0.5).

[0014] In some embodiments, the concentrated acid in the concentrated acid alcohol solution is one of concentrated hydrochloric acid or concentrated sulfuric acid; the alcohol is one or more of ethanol, ethylene glycol, glycerol, and n-butanol.

[0015] In a second aspect, the present invention provides a composite quantum dot electrode material prepared by the method for preparing a composite quantum dot electrode material according to any one of the first aspect.

[0016] In a third aspect, the present invention provides an application of the composite quantum dot electrode material described in the second aspect in petrochemical industry.

[0017] In a fourth aspect, the present invention provides an application according to the third aspect, which is used for polymer flooding in oil fields.

[0018] Polymer flooding technology is a key method in the tertiary oil recovery of oilfields, effectively improving the recovery rate of oil wells with high water cut. However, the efficiency of polymer flooding depends on the viscosity of its solution, which is easily affected by biological, chemical, and mechanical factors, resulting in a decline in the stability of the polymer solution and the flooding effect. Although the conventional method of preparing polymers with sewage alleviates the environmental pollution caused by the discharged sewage from oilfields during the extra-high water cut period to a certain extent and reduces the waste of fresh water resources, the reducing ions and other non-ideal components in the sewage will cause a significant loss in the viscosity of the polymer, seriously affecting the recovery effect. Therefore, improving the viscosity stability of polymers and reducing viscosity loss are the keys to improving the flooding efficiency.

[0019] The present invention innovatively proposes a scheme for treating sewage by using electrochemically prepared nanobubbles, making full use of the characteristics of high stability, strong oxidizing property, and high gas-liquid mass transfer efficiency of nanobubbles. By electrochemically reacting to prepare nanobubbles, nanoscale bubbles can be generated in the solution. These bubbles release energy when they collapse, affecting the formation structure in the form of high temperature and high pressure, and having good plugging and adjusting performance. In addition, the electrochemical process effectively removes oil, suspended solids, reducing metal ions, and sulfur ions in the sewage, significantly reducing the bacterial content in the sewage and slightly increasing the pH value, thereby enhancing the viscosity stability of the polymer solution, significantly reducing the viscosity loss phenomenon, and improving the flooding efficiency.

[0020] Using the electrochemically prepared nanobubble technology to treat oilfield sewage innovatively solves the problem of pollution caused by the discharged sewage from oilfields during the high water cut period and reduces the waste of fresh water. At the same time, by removing the adverse components in the sewage, the viscosity stability of the polymer solution is enhanced, and the oil recovery efficiency is improved.

[0021] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: (1) The preparation method of the composite quantum dot electrode material proposed by the present invention uses a titanium-based material as the substrate and undergoes multi-step cleaning and surface oxide film removal treatments to ensure the cleanliness and activity of the substrate. At the same time, by reacting molybdenum source and sulfur source to synthesize MoS2@QDs and mixing them with antimony salt and rare earth metal salt to form a stable impregnating solution, a composite quantum dot electrode material with excellent conductivity and electrocatalytic activity is obtained through calcination. The preparation method has a clear process flow and simple process control, and the obtained material has a uniform structure and stable performance.

[0022] (2) The composite quantum dot electrode material prepared by the present invention has significant conductivity and can effectively improve the electron transfer rate of the electrode material. At the same time, the combination of MoS2@QDs and rare earth metal salt enhances the electrocatalytic performance of the material, significantly increasing the reaction rate in the electrochemical reaction and being applicable to high-efficiency electrocatalytic application scenarios.

[0023] (3) The composite quantum dot electrode material prepared by the present invention significantly improves the corrosion resistance and stability during long-term operation through a unique synthesis process. The combination of the titanium-based material and the quantum dots effectively avoids the problems of easy corrosion and failure of traditional electrode materials in harsh environments such as oilfields, enabling it to maintain durable performance during oilfield applications.

[0024] (4) The high electrocatalytic activity and stability of the composite quantum dot electrode material prepared by the present invention make it suitable for the electrochemical process in polymer flooding in oilfields, capable of improving sewage treatment efficiency, enhancing the viscosity stability of polymer solutions, reducing viscosity loss, and significantly increasing oil production efficiency. In addition, the nanobubbles generated through the electrochemical process also have a plugging and adjusting effect, improving the formation fluid environment and providing a new technical means for long-term oil displacement in oilfields.

[0025] (5) The composite quantum dot electrode material prepared by the present invention has characteristics such as strong conductivity, high electrocatalytic activity, good corrosion resistance, and long-lasting stability, and is suitable for practical application scenarios such as oilfield sewage treatment and polymer flooding, with broad market application prospects. Through the process method and material characteristics of the present invention, it can promote the innovation of oilfield oil production technology, bringing significant economic and social benefits. Description of the Drawings

[0026] Figure 1 is the SEM image of the Ti / Sb-La-MoS2@QDs composite quantum dot electrode material prepared in Example 1 of the present invention with a Mo:Sb:La (molar ratio) of 3:1:0.1 and ethanol as the solvent.

[0027] Figure 2 is the SEM image of the Ti / Sb-Sc-MoS2@QDs composite quantum dot electrode material prepared in Example 2 of the present invention with a Mo:Sb:Sc (molar ratio) of 2:1:0.2 and ethylene glycol as the solvent.

[0028] Figure 3 is the SEM image of the Ti / Sb-Y-MoS2@QDs composite quantum dot electrode material prepared in Example 3 of the present invention with a Mo:Sb:Y (molar ratio) of 5:1:0.3 and glycerol as the solvent.

[0029] Figure 4 is the flow chart of a method for preparing a composite quantum dot electrode material provided by an embodiment of the present invention. Detailed Embodiments

[0030] The following further elaborates the present invention in conjunction with specific embodiments. It should be understood that the embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. Modifications in various equivalent forms made by those skilled in the art to the present invention all fall within the scope defined by the appended claims of this application.

[0031] Unless otherwise specified, the test methods used in the following examples are all conventional methods; the materials, reagents, etc. used are, unless otherwise specified, reagents and materials that can be obtained commercially.

[0032] Appendix Figure 4 The following is a flowchart of a method for preparing a composite quantum dot electrode material provided by an embodiment of the present invention, including the following steps: Step S1: Polish and wash the titanium-based material, ultrasonically clean it with acetone, rinse it with distilled water to remove acetone, and soak it in a first acidic solution to remove the oxide film, and then soak the titanium-based material in a second acidic solution for storage to obtain a titanium substrate; Among them, the first acidic solution is an oxalic acid solution with a concentration of 1% - 10%, and the soaking time of the titanium-based material in the first acidic solution is 1 - 3 h; the second acidic solution is an oxalic acid solution with a concentration of 0.1% - 5%. It should be noted that those skilled in the art can also use other solutions for substitution, and the present invention is not limited thereto.

[0033] Step S2: Dissolve the molybdenum source in water and adjust the pH value to 5 - 7 with a pH regulator. After adding the sulfur source in a preset ratio and fully dissolving and mixing, transfer it to a reaction kettle and carry out a thermal reaction at 120 - 200 °C for 24 - 48 h; after the reaction is completed, filter, centrifuge, dialyze, and freeze-dry the obtained reaction solution to obtain MoS2@QDs; In the present invention, the molybdenum source is one or two of ammonium molybdate and sodium molybdate; the sulfur source is one or more of sodium sulfide, L-cysteine, and glutathione; the molar ratio of the molybdenum source to the sulfur source is Mo∶S = 1∶(2 - 4); the pH regulator uses a hydrochloric acid solution HCl with a concentration of 0.1% - 1% or ammonia water with a concentration of 0.1% - 1%, but is not limited thereto, and those skilled in the art can use other pH regulators for substitution; Step S3: Mix the obtained MoS2@QDs, antimony salt, and rare earth metal salt in a preset ratio and dissolve them in an alcohol solution of concentrated acid to obtain an impregnation solution; preferably, the molar ratio of Mo:Sb:Re in the MoS2@QDs, antimony salt, and rare earth metal salt is (2 - 5):1:(0.1 - 0.5), and the rare earth element Re of the rare earth metal salt is selected from one or more of 17 chemical elements including scandium, yttrium, and lanthanide elements; Furthermore, the concentrated acid in the alcohol solution of concentrated acid is one of concentrated hydrochloric acid or concentrated sulfuric acid; the alcohol is one or more of ethanol, ethylene glycol, glycerol, and n-butanol.

[0034] Step S4: Clean the titanium substrate, dry it at 60-120 °C, then completely immerse it in the impregnation solution. After the impregnation is completed, place it in an oven to dry, then place it in a muffle furnace for calcination. After repeating the impregnation, drying, and calcination processes multiple times, let it cool naturally, then wash it with distilled water and dry it to obtain the composite quantum dot electrode material.

[0035] Preferably, clean and dry the titanium substrate, then completely immerse it in the impregnation solution. After the impregnation is completed, take it out and blow dry, and place it in an oven to dry at 125-135 °C for 5-20 min, then place it in a muffle furnace to calcine at 250-300 °C for 5-20 min. Repeat this process 8-10 times, and for the last calcination, carry out for 1-2 h. After natural cooling, rinsing with distilled water, and drying, the composite quantum dot electrode material is obtained.

[0036] The present invention also prepares the composite quantum dot electrode material by the described preparation method, and applies the composite quantum dot electrode material in petrochemical industry, including but not limited to being used for polymer flooding in oilfields.

[0037] The following further elaborates on the technical solutions in the present invention in conjunction with embodiments, but is not limited thereto. Example 1

[0038] The following further elaborates on this Example 1 in conjunction with the attached Figure 1 Make a further detailed description of this Example 1.

[0039] A preparation method of a composite quantum dot electrode material provided by an embodiment of the present invention includes the following steps: Step 1: When performing surface treatment on the titanium-based material, mechanical grinding can be used. Grind a circular titanium-based material with a thickness of 4 mm and a diameter of 1.50 cm with 120# and 500# sandpapers to remove the rough layer and impurities on the surface; then rinse the titanium-based material with water and place it in acetone for ultrasonic cleaning for 20 min to remove organic pollutants on the surface. After the ultrasonic cleaning is completed, remove the acetone on the surface of the titanium sheet with distilled water, and then place the titanium-based material in 5% oxalic acid for micro-boiling for 1 h for pickling treatment to remove the oxide film generated by the matrix due to long-term placement. Finally, store the obtained titanium substrate in 0.5% oxalic acid solution for standby.

[0040] Step 2: Dissolve 0.6414 g of sodium molybdate dihydrate as the molybdenum source in 5 mL of deionized water, adjust the pH to 7.0 with 0.5% HCl, dissolve 0.3103 g of sodium sulfide as the sulfur source in 10 mL of deionized water, mix the above solutions and stir for 5 min until completely dissolved, transfer to a 50 mL stainless steel reaction kettle lined with polytetrafluoroethylene, seal it, and place it in an oven at 200 °C for reaction for 24 h.

[0041] After the reaction ended and cooled down, the reaction solution was filtered through a 0.22 μm microporous membrane to remove suspended solids, centrifuged at 4000 r / min for 15 min, and dialyzed through a dialysis bag with a cut-off molecular weight of 300 Da for 24 h to obtain the MoS2@QDs solution, which was then freeze-dried to obtain MoS2@QDs.

[0042] Step 3: Mix the MoS2@QDs, SbCl3, and La(NO3)3•6H2O prepared in Step 2 in a molar ratio of Mo:Sb:La = 3:1:0.1, and dissolve them in an ethanol solution of concentrated hydrochloric acid to make an impregnating solution.

[0043] Step 4: Clean the titanium substrate reserved in a 0.5% oxalic acid solution (the second acidic solution) in Step 1 for standby, and dry it at 60 °C. Immerse the treated titanium substrate in the impregnating solution, take it out, blow off the excess impregnating solution on the surface with a hair dryer, place it in an oven at 125 ºC and dry for 15 min, then place it in a muffle furnace at 300 ºC and calcine for 15 min. Repeat the above procedure 10 times. For the last time, place it in a muffle furnace at 300 ºC and calcine for 2 h, cool it naturally, take it out, wash it with distilled water and dry it to obtain the composite quantum dot electrode material Ti / Sb-La-MoS2@QDs, which is stored in a vacuum desiccator for standby.

[0044] As shown in the appendix Figure 1 It can be seen that the prepared composite quantum dot electrode material Ti / Sb-La-MoS2@QDs mainly has the following characteristics: High specific surface area: The composite quantum dot electrode material has a high specific surface area. After adding a certain proportion of rare metal La, it provides more active sites, higher catalytic activity and charge transfer efficiency, which is more conducive to the progress of the polarization reaction.

[0045] Bubble dynamic effect: The nanobubbles formed on the surface of the composite quantum dot electrode material have unique dynamic behaviors, which affect the microenvironment of the electrode surface, improve the mass transfer between the solution and the electrode, reduce the mass transfer resistance, and increase the reaction rate and direction.

[0046] Stability and durability: After adding the rare metal La, the stability of the electrode material is enhanced and the service life of the electrode material is extended. The nanobubbles generated on the electrode surface are more likely to form a stable film on the electrode surface due to their small size, protecting the electrode material from corrosion and wear. At the same time, the dynamic behavior of the nanobubbles generated on the composite quantum dot electrode also helps to slow down the passivation behavior of the electrode surface and extend the service life of the electrode.

[0047] The nano-bubbles generated during the polarization of the prepared composite quantum dot electrode material in the polymer flooding wastewater in oil fields can increase the fluidity of the wastewater, improve the sewage properties, enhance the oil displacement efficiency, reduce the waste of water resources, and decrease the use of chemicals. This not only reduces energy consumption and costs but also minimizes the negative impact on the environment during the oil displacement process.

[0048] The prepared composite quantum dot electrode material Ti / Sb-La-MoS2@QDs was applied to the polymer-flooded sewage in the fifth operation area of an oil production plant, and the conventional detection data of the polymer-flooded sewage at different polarization times of the composite quantum dot electrode material were compared and tested (see Table 1), as well as the viscosity stability data of the polymer solutions prepared from the polymer-flooded sewage treated at different polarization times at the corresponding times (see Table 2).

[0049] Table 1 Conventional detection data of the polymer-flooded sewage by the composite quantum dot electrode material at different polarization times Table 2 Viscosity stability data of the polymer solutions prepared from the polymer-flooded sewage treated at different polarization times at the corresponding times As can be seen from Table 1 and Table 2, after the sewage is polarized by the electrode prepared from the composite quantum dot material, the contents of oil, suspended solids, reducing metal ions, reducing sulfur ions, and bacteria in the sewage decrease significantly. The viscosity stability of the polymer prepared from the sewage is greatly improved, the viscosity loss decreases significantly, and the viscosity retention rate tends to be stable with the increase of the polarization time. This can not only improve the polymer flooding oil recovery rate but also solve problems such as water resource waste and sewage discharge. Example 2

[0050] The following combines the attached Figure 2 to further elaborate on this Example 2.

[0051] A preparation method of a composite quantum dot electrode material provided by an embodiment of the present invention includes the following steps: Step 1: Grind a circular titanium-based material with a thickness of 4 mm and a diameter of 1.50 cm using 120# and 500# sandpapers. After rinsing it clean with water, place it in acetone and ultrasonically clean it for 30 min. Then remove the acetone on the surface of the titanium-based material with distilled water, place it in 10% oxalic acid and boil it gently for 2 h to remove the oxide film generated by the long-term placement of the substrate. Finally, store it in a 1% oxalic acid solution for standby.

[0052] Step 2: 0.2341 g of ammonium molybdate tetrahydrate was dissolved in 5 mL of deionized water, and the pH was adjusted to 7.0 with 0.5 % HCl. 0.9311 g of L-cysteine as the sulfur source was dissolved in 10 mL of deionized water. The above solutions were mixed and stirred for 15 min until completely dissolved, then transferred to a 50 mL stainless steel reactor lined with polytetrafluoroethylene, sealed, and placed in an oven at 180 ºC for reaction for 36 h. After the reaction ended and cooled, the reaction solution was filtered through a 0.22 μm microporous membrane to remove suspended solids, centrifuged at 4000 r / min for 15 min, and dialyzed through a dialysis bag with a cut-off molecular weight of 300 Da for 24 h to obtain the MoS2@QDs solution, which was then freeze-dried to obtain MoS2@QDs.

[0053] Step 3: The MoS2@QDs, SbCl3, and Sc(NO3)3•H2O prepared in Step 2 were mixed according to the molar ratio of Mo:Sb:Sc = 2:1:0.2 and dissolved in an ethylene glycol solution of concentrated hydrochloric acid to prepare an impregnating solution.

[0054] Step 4: The substrate in Step 1 was immersed in the impregnating solution, taken out, and the excess impregnating solution on the surface was blown off with a hair dryer, then dried in an oven at 135 ºC for 20 min, and then calcined in a muffle furnace at 300 ºC for 20 min. The above procedure was repeated 8 times. The last time, it was calcined in a muffle furnace at 300 ºC for 1.5 h, cooled naturally, taken out, washed with distilled water, and dried to obtain the composite quantum dot electrode material Ti / Sb-Sc-MoS2@QDs, which was stored in a vacuum desiccator for later use.

[0055] As shown in the appendix Figure 2 It can be seen that the prepared composite quantum dot electrode material Ti / Sb-Sc-MoS2@QDs has the following characteristics: High specific surface area: The composite quantum dot electrode material has a high specific surface area. After adding the rare metal Sc, the catalytic activity of the electrode material is significantly improved, providing more active sites and charge transfer efficiency, which is more conducive to the progress of the polarization reaction.

[0056] Bubble dynamic effect: The nanobubbles formed on the surface of the composite quantum dot electrode material have unique dynamic behaviors, which affect the microenvironment of the electrode surface, improve the mass transfer between the solution and the electrode, reduce the mass transfer resistance, and increase the reaction rate and direction.

[0057] Stability and durability: After adding rare metal Sc to the composite quantum dot electrode material, the temperature resistance and mechanical strength of the composite quantum dot electrode material can be improved, enhancing the stability and durability of the electrode material. The nano-bubbles generated on the electrode surface are more likely to form a stable thin film on the electrode surface due to their small size, protecting the electrode material from corrosion and wear. At the same time, the dynamic behavior of the nano-bubbles generated on the composite quantum dot electrode also helps to slow down the passivation behavior of the electrode surface and extend the service life of the electrode.

[0058] The nano-bubbles generated during the polarization of the prepared composite quantum dot electrode material in the produced wastewater from polymer flooding in oilfields can increase the fluidity of the wastewater, improve the sewage properties, enhance the oil displacement efficiency, reduce water resource waste, and lower the use of chemicals. This not only reduces energy consumption and costs but also minimizes the negative impact on the environment during the oil displacement process.

[0059] Apply the prepared composite quantum dot electrode material Ti / Sb-Sc-MoS2@QDs to the produced wastewater after polymer flooding in the fifth operation area of an oil production plant, and compare and test the conventional detection data of the produced wastewater after polymer flooding at different polarization times of the composite quantum dot electrode material (see Table 3) and the viscosity stability data of the polymer solution prepared from the produced wastewater treated at different polarization times at the corresponding times (see Table 4).

[0060] Table 3 Conventional detection data of the produced wastewater after polymer flooding by the composite quantum dot electrode material at different polarization times Table 4 Viscosity stability data of the polymer solution prepared from the produced wastewater treated at different polarization times at the corresponding times As can be seen from Table 3 and Table 4, after the sewage is polarized by the electrode prepared from the composite quantum dot material, the contents of oil, suspended solids, reducing metal ions, reducing sulfur ions, and bacteria in the sewage decrease significantly. The viscosity stability of the polymer prepared from the sewage is greatly improved, the viscosity loss decreases significantly, and the viscosity retention rate tends to be stable with the increase of the polarization time. This can not only improve the oil recovery rate of polymer flooding but also solve problems such as water resource waste and sewage discharge. Example 3

[0061] The following is a further detailed description of this Example 3 in combination with the attached Figure 3 Make a further detailed description of this Example 3.

[0062] A preparation method of a composite quantum dot electrode material provided by an embodiment of the present invention includes the following steps: Step 1: A circular titanium-based material with a thickness of 4 mm and a diameter of 1.50 cm is polished with 120# and 500# sandpapers, rinsed thoroughly with water, and then ultrasonically cleaned in acetone for 40 min. Subsequently, the acetone on the surface of the titanium sheet is removed with distilled water, and the sheet is placed in 7% oxalic acid and boiled gently for 2 h to remove the oxide film generated due to long-term storage of the substrate. Finally, it is stored in a 0.5% oxalic acid solution for later use.

[0063] Step 2: 0.6553 ammonium molybdate is dissolved in 5 mL of deionized water, and the pH is adjusted to 7.0 with 0.5% HCl. 1.0280 g of glutathione is added as a sulfur source and dissolved in 10 mL of deionized water. The above solutions are mixed and stirred for 5 min until completely dissolved, then transferred to a 50 mL stainless steel reaction kettle lined with polytetrafluoroethylene, sealed, and placed in an oven at 120 ºC for reaction for 48 h. After the reaction is completed and cooled, the reaction solution is filtered through a 0.22 μm microporous membrane to remove suspended matter, centrifuged at 4000 r / min for 15 min, and dialyzed through a dialysis bag with a cut-off molecular weight of 300 Da for 24 h to obtain a MoS2@QDs solution, which is then freeze-dried to obtain MoS2@QDs.

[0064] Step 3: The MoS2@QDs, SbCl3, and Y(NO3)3•6H2O prepared in Step 2 are mixed according to the molar ratio of Mo:Sb:Y = 5:1:0.3 and dissolved in a glycerol solution of concentrated hydrochloric acid to prepare an impregnating solution. Step 4: The substrate in Step 1 is immersed in the impregnating solution, taken out, and the excess impregnating solution on the surface is blown off with a hair dryer, then dried in an oven at 125 ºC for 15 min, and then calcined in a muffle furnace at 300 ºC for 15 min. The above procedure is repeated 10 times, and the last time it is calcined in a muffle furnace at 300 ºC for 2 h, cooled naturally, taken out, washed with distilled water, and dried to obtain a composite quantum dot electrode material Ti / Sb-Y-MoS2@QDs, which is stored in a vacuum desiccator for later use.

[0065] As shown in the appendix Figure 3 It can be seen that the prepared composite quantum dot electrode material Ti / Sb-Y-MoS2@QDs has the following characteristics: High specific surface area: The composite quantum dot electrode material has a high specific surface area. After adding the rare metal Y, the catalytic activity of the electrode material is significantly improved, providing more active sites and charge transfer efficiency, which is more conducive to the progress of the polarization reaction.

[0066] Bubble dynamic effect: The nanobubbles formed on the surface of the composite quantum dot electrode material have unique dynamic behaviors, which affect the microenvironment of the electrode surface, improve the mass transfer between the solution and the electrode, reduce the mass transfer resistance, and increase the reaction rate and direction.

[0067] Stability and durability: After adding rare metal Y to the composite quantum dot electrode material, the temperature resistance and mechanical strength of the composite quantum dot electrode material can be improved, and the stability and durability of the electrode material can be enhanced. The nano-bubbles generated on the electrode surface are more likely to form a stable thin film on the electrode surface due to their tiny size, protecting the electrode material from corrosion and wear. At the same time, the dynamic behavior of the nano-bubbles generated on the composite quantum dot electrode also helps to slow down the passivation behavior of the electrode surface and extend the service life of the electrode.

[0068] The nano-bubbles generated during the polarization of the prepared composite quantum dot electrode material in the produced wastewater of polymer flooding in oilfields can increase the fluidity of the wastewater, improve the sewage properties, enhance the oil displacement efficiency, reduce the waste of water resources, and decrease the use of chemicals. This not only reduces energy consumption and costs but also minimizes the negative impact on the environment during the oil displacement process.

[0069] The prepared composite quantum dot electrode material Ti / Sb-Y-MoS2@QDs was applied to the produced wastewater after polymer flooding in the fifth operation area of an oil production plant, and the conventional detection data of the produced wastewater after polymer flooding at different polarization times of the composite quantum dot electrode material were compared and tested (see Table 5), as well as the viscosity stability data of the polymer solution prepared from the produced wastewater after polymer flooding treated at different polarization times at the corresponding times (see Table 6).

[0070] Table 5 Conventional detection data of the produced wastewater after polymer flooding by the composite quantum dot electrode material at different polarization times Table 6 Viscosity stability data of the polymer solution prepared from the produced wastewater after polymer flooding treated at different polarization times at the corresponding times As can be seen from Table 5 and Table 6, after the sewage is polarized by the electrode prepared from the composite quantum dot material, the contents of oil, suspended solids, reducing metal ions, reducing sulfur ions, and bacteria in the sewage decrease significantly. The viscosity stability of the polymer prepared from the sewage is greatly improved, the viscosity loss decreases significantly, and the viscosity retention rate tends to be stable with the increase of the polarization time. This can not only improve the oil recovery rate of polymer flooding but also solve problems such as water resource waste and sewage discharge.

[0071] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing a composite quantum dot electrode material, characterized in that: The steps include: The titanium-based material is polished, washed with water, ultrasonically cleaned with acetone, rinsed with distilled water to remove the acetone, and immersed in a first acidic solution to remove the oxide film, and then immersed in a second acidic solution for storage to obtain a titanium matrix; The molybdenum source is dissolved in water and the pH value is adjusted to 5-7 by a pH regulator. The sulfur source is added in a preset ratio and fully dissolved and mixed, and then transferred to a reactor for thermal reaction at 120-200°C for 24-48 hours. After the reaction, the obtained reaction solution is filtered, centrifuged, dialyzed, and freeze-dried to obtain MoS2@QDs. The prepared MoS2@QDs, antimony salt, and rare earth metal salt are mixed in a preset ratio and dissolved in a concentrated acid alcohol solution to prepare an impregnation solution; The titanium substrate is cleaned and dried, and then completely immersed in the impregnation solution. After the impregnation is completed, it is placed in an oven for drying, and then placed in a muffle furnace for calcination. After the impregnation, drying and calcination processes are repeated many times, the substrate is naturally cooled, and then washed with distilled water and dried to obtain a composite quantum dot electrode material.

2. The method for preparing a composite quantum dot electrode material according to claim 1, characterized in that: The titanium-based material is polished using sandpaper with a mesh size of 120-500; the acetone ultrasonic cleaning time is 20-40 min; the first acidic solution is an oxalic acid solution with a concentration of 1%-10%, and the titanium-based material is immersed in the first acidic solution for 1-3 hours; the second acidic solution is an oxalic acid solution with a concentration of 0.1%-5%.

3. The method for preparing a composite quantum dot electrode material according to claim 2, characterized in that: The molybdenum source is one or two of ammonium molybdate and sodium molybdate; the sulfur source is one or more of sodium sulfide, L-cysteine, and glutathione; the molar ratio of the molybdenum source to the sulfur source is Mo:S=1:(2-4); the pH regulator is a hydrochloric acid solution HCl with a concentration of 0.1-1% or ammonia water with a concentration of 0.1-1%.

4. The method for preparing a composite quantum dot electrode material according to claim 3, characterized in that: The rare earth element Re of the rare earth metal salt is selected from one or more of 17 chemical elements including scandium, yttrium and lanthanide elements.

5. The method for preparing a composite quantum dot electrode material according to claim 4, characterized in that: The molar ratio of Mo:Sb:Re in the MoS2@QDs, antimony salt and rare earth metal salt is (2 - 5):1:(0.1 - 0.5).

6. The method for preparing a composite quantum dot electrode material according to claim 5, characterized in that: The concentrated acid in the alcohol solution of concentrated acid is one of concentrated hydrochloric acid and concentrated sulfuric acid; the alcohol is one or more of ethanol, ethylene glycol, glycerol and n-butanol.

7. The method for preparing a composite quantum dot electrode material according to claim 6, characterized in that: The titanium substrate is cleaned and dried, and then completely immersed in the impregnation solution. After the impregnation is completed, it is taken out and blown dry, and then placed in an oven at 125~135ºC for 5~20 minutes, and then placed in a muffle furnace for calcination at 250~300ºC for 5~20 minutes. This is repeated 8~10 times, and the last calcination is 1~2 hours. After natural cooling, rinsing with distilled water, and drying, a composite quantum dot electrode material is obtained.

8. A composite quantum dot electrode material obtained according to the composite quantum dot electrode material preparation method according to any one of claims 1 to 7.

9. Application of the composite quantum dot electrode material according to claim 8 in petrochemical industry.

10. The use according to claim 9, characterized in that: Used in polymer flooding in oil fields.

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