A method and device for catalytic oxidation of volatile organic compounds based on molybdenum-based cathode electrode and electric field enhancement

Abstract

This invention provides a method for field-enhanced catalytic oxidation of volatile organic compounds (VOCs) based on a molybdenum-based cathode electrode, comprising: preparing cathode and anode catalytic electrode plates; arranging multiple electrode plates in parallel and connecting them to a DC power supply to form an alternating anode and cathode catalytic electrode array; applying a 30-80V DC voltage to the array and performing periodic short-time reversal operations; and introducing VOC-containing gas into the array in a direction parallel to the electrode plate surface. This invention also provides an apparatus for implementing this method. This invention utilizes the synergistic effect of molybdenum diselenide and p-type semiconductor materials to efficiently catalyze the reaction of oxygen and water molecules under a low-voltage electric field, generating a strong oxidizing substance dominated by singlet oxygen, thus thoroughly degrading VOCs; the periodic short-time reversal prevents electrode passivation, ensuring long-term operational stability. This invention has the advantages of low energy consumption, no ozone byproducts, safety and reliability, and long service life, and is suitable for household and industrial air purification applications.

Description

Technical Field

[0001] This invention belongs to the field of air purification and catalytic oxidation technology, specifically relating to a method and apparatus for electric field-enhanced catalytic oxidation of volatile organic compounds based on a molybdenum-based cathode electrode. Background Technology

[0002] Volatile organic compounds (VOCs) are a significant component of air pollutants, widely present in industrial waste gases, vehicle emissions, chemical production, and the use of paints and solvents. VOC emissions not only severely impact the environment and air quality but may also pose health risks. Therefore, efficient VOC removal has become a key research focus in the field of environmental governance.

[0003] Corona discharge and dielectric barrier discharge (DBD) are common non-thermal plasma methods widely used in the degradation of VOCs. These technologies rely on gas discharge at high voltages of several thousand to tens of thousands of volts to generate a large number of high-energy electrons and reactive particles (such as O3, •OH, etc.) to achieve the oxidative degradation of pollutants. Although these technologies can operate at room temperature, they have the following significant drawbacks: (1) High voltage dependence and high energy consumption: Maintaining a high voltage of several thousand to tens of thousands of volts continuously not only results in high equipment energy consumption but also imposes stringent requirements on power supplies and insulation materials; (2) Byproduct generation: Large amounts of ozone (O3) and nitrogen oxides (NOx) are generated during high-voltage discharge. x Secondary pollutants such as ) may cause harm to the environment and human health; (3) Complex equipment and high maintenance costs: In order to ensure stable operation, a complex power supply system and a high-voltage discharge device are required, and the equipment manufacturing and maintenance costs are high; (4) Insufficient stability: Poor discharge uniformity, local high-energy discharge can easily cause catalyst deactivation or material loss, and long-term operation stability is limited. Therefore, how to achieve efficient and complete degradation of VOCs under low energy consumption and low temperature conditions, and avoid secondary pollution, remains a technical challenge that urgently needs to be solved. Summary of the Invention

[0004] One of the objectives of this invention is to provide a method for the electric field-enhanced catalytic oxidation of volatile organic compounds based on a molybdenum-based cathode electrode. Under a mild, low-energy-consumption electric field, the method catalyzes the generation of strong oxidizing substances such as hydrogen peroxide and singlet oxygen from oxygen molecules, thereby efficiently decomposing harmful gases and purifying the air.

[0005] The second objective of this invention is to provide an apparatus for the electric field-enhanced catalytic oxidation of volatile organic compounds based on a molybdenum-based cathode electrode.

[0006] One of the technical solutions adopted to achieve the objective of this invention is: to provide a method for the electric field-enhanced catalytic oxidation of volatile organic compounds based on a molybdenum-based cathode electrode, comprising the following steps: Catalytic electrode plates were prepared, with the active component of the cathode catalytic electrode plate being molybdenum diselenide; and the active component of the anode catalytic electrode plate being a p-type semiconductor material. Multiple cathode catalytic electrode plates and multiple anode catalytic electrode plates are arranged alternately in parallel and connected to a DC power supply to form a catalytic electrode array. A DC voltage of 30-80V is applied to the catalytic electrode array to generate an electric field between the electrodes, and the operation is performed cyclically: first, the current electric field polarity is maintained for 20-45 minutes, then the DC voltage is reversed for 2-10 seconds, and the original polarity is restored after the reversal is completed. A gas containing volatile organic compounds is introduced into the catalytic electrode array in a direction parallel to the surface of the catalytic electrode plates.

[0007] The overall concept and inventive principle of this invention are as follows: The core idea of ​​this invention lies in constructing a catalytic system that synergistically combines a specific catalyst (MoSe2 cathode and p-type semiconductor anode) with a specific low-energy electric field (30-80V DC). This system leverages the electric field to directionally enhance the catalytic process, efficiently generating singlet oxygen (…). 1 It mainly uses highly reactive oxygen species (O2) to achieve efficient and complete oxidation of VOCs under mild conditions.

[0008] Its invention principles are mainly based on the following aspects: First, this invention selects molybdenum diselenide (MoSe2) as the cathode catalyst, utilizing its properties as an n-type semiconductor. Molybdenum (Mo) is a variable valence metal (such as Mo...). 4+ / Mo 2+ Selenium (Se) also has variable valence (e.g., Se) 2- / Se 0 Under an electric field, reversible redox reactions can occur, providing abundant active sites and flexible channels for electron transfer and oxygen molecule activation. Matching this, a p-type semiconductor material is chosen as the anode material, forming a complementary system with MoSe2, which promotes the separation and directional migration of charge carriers (electron-hole pairs) in the electric field, forming a highly efficient catalytic closed loop.

[0009] Secondly, the above catalytic process is greatly enhanced under the action of an applied DC electric field: On the cathode catalytic electrode, oxygen molecules from polluted air are adsorbed onto catalytically active sites on the MoSe2 surface. These active sites include molybdenum (Mo) and selenium (Se) edge sites, selenium vacancies, and interlayer defects. As shown in Equation 1, at these sites, adsorbed O2 molecules accept electrons from the MoSe2 conduction band (ee). - ) is converted into oxygen negative ions (O2) •- Simultaneously, the molybdenum selenide cathode gains electrons, transitioning from a high valence state to a low valence state (Equation 2). Oxygen anions (O2) - The hydrogen peroxide (H2O2) reacts with water molecules adsorbed on the surface to generate hydrogen peroxide (H2O2), which then reacts with the water molecules adsorbed on the surface of the Mo. 2+ Under catalysis, singlet oxygen is further produced ( 1 O2 (as in formula 3-4).

[0010] At the anodic catalytic electrode, the holes (h) on Cu2O + It oxidizes water molecules, producing oxygen (O2) and protons (H+). + ) and electrons (e - As shown in Equation 5. Singlet oxygen ( 1 O2 has strong oxidizing properties and can continuously oxidize and degrade volatile organic compound (VOC) pollutants.

[0011] Cathode reaction: O2+ MoSe2(e - → O2 •- + MoSe2 (Equation 1) Mo 4+ + 2e - → Mo 2+ (Formula 2) 2O2 •- + 2H₂O → H₂O₂ + O₂ + 2OH⁻ - (Formula 3) Mo 2+ + 2H2O2→ Mo 4+ + 1 O2+ 2H2O (Formula 4) Anode reaction: 2H₂O → O₂ + 4H + +4e - (Or expressed as 2H2O+4h) + → O2 + 4H + ) (Formula 5) An applied electric field can effectively promote the aforementioned catalytic oxidation process. Specifically, the electric field can drive the migration of electrons from the valence band to the conduction band in molybdenum selenide, thereby promoting the effective separation of electrons in the conduction band and holes in the valence band. During this process, the recombination of electrons and holes is reduced, the electron migration rate in the conduction band is accelerated, and the electron density on the catalyst surface is increased, allowing molybdenum and selenium atoms on the surface to donate electrons more efficiently, thus promoting the oxygen reduction reaction. In addition, the electric field can also change the local potential on the surface of molybdenum selenide, reducing the adsorption energy between reactant molecules such as oxygen and hydrogen peroxide and the catalyst surface, enhancing the adsorption capacity of reactant molecules. Through this mechanism, the electric field improves the activation efficiency of oxygen and water molecules, enabling the catalyst surface to participate more efficiently in the oxygen reduction reaction and the generation of reactive oxygen species. The applied electric field can also optimize the distribution of defect sites on the catalyst surface, enhance the catalytic activity of defect sites, improve the stability of the catalyst, and thus maintain its high efficiency in long-term catalytic reactions. The present invention sets the voltage of the DC electric field to 30-80 V. The electric field strength in this range is sufficient to effectively drive the separation and migration of electrons and holes inside the catalyst, as well as the efficient activation of oxygen molecules, ensuring a high yield of active oxygen species, while avoiding side reactions such as air breakdown and ozone generation that may be caused by higher voltage.

[0012] Finally, the key design of this invention involves a DC voltage cycle that first maintains the current electric field polarity for 20-45 minutes, then performs a short-term reversal of the DC voltage for 2-10 seconds, followed by restoring the original polarity. During continuous cathodication, molybdenum-based cathodes experience phenomena such as edge sites being covered by intermediates and charge accumulation, reducing catalytic efficiency. Short-term reversal allows for rapid oxidation and desorption of adsorbed intermediates on the cathode surface, thereby restoring active sites and maintaining the long-term stability of the catalyst. Furthermore, given the oxidation risk of MoSe2 at high potentials, this invention controls the reversal time to within 2-10 seconds and restores the original polarity after reversal, effectively preventing material oxidation and deactivation without significantly affecting the VOC removal efficiency throughout the treatment cycle. In addition, ensuring the pollutant gas flows parallel to the electrode surface guarantees sufficient and uniform contact between the VOCs gas and the entire catalytically active area of ​​the electrode surface, improving mass transfer efficiency, avoiding gas flow short-circuiting, and thus maximizing purification efficiency.

[0013] Furthermore, the method for preparing the catalytic electrode plate includes: coating a slurry containing active ingredients, conductive substances, binders and solvents onto an electrode substrate, and then drying it to form a catalytic coating on the electrode substrate.

[0014] Furthermore, in the cathode catalytic electrode plate, molybdenum diselenide accounts for 60%-90% of the mass percentage of the catalytic coating. The active ingredient is the core of the catalytic reaction, and its content directly affects the number of catalytic sites. If the content is too low, there will be insufficient active sites, and the catalytic efficiency will decrease significantly; if the content is too high, the conductivity and mechanical adhesion of the coating will deteriorate, affecting the stability and service life of the electrode.

[0015] Furthermore, in the anode catalytic electrode plate, the p-type semiconductor material includes one or more combinations of cuprous oxide, copper oxide, nickel oxide, and cuprous sulfide; the p-type semiconductor material accounts for 60%-90% of the mass percentage of the catalytic coating.

[0016] Furthermore, the electrode substrate includes one of copper plate, aluminum plate, nickel plate, and graphite plate, with a thickness of 0.5-2 mm.

[0017] Furthermore, the conductive material is one or more of the following: coconut shell activated carbon, conductive carbon black, conductive graphite, carbon nanotubes, supercapacitor activated carbon, and conductive carbon fiber. The conductive material accounts for 5%-20% of the mass percentage of the catalytic coating. The conductive material constructs a conductive network inside the electrode, ensuring that the electric field can effectively act on the entire catalytic coating. If the content is too low, the coating resistance will be too high, affecting efficiency; while if the content is too high, it will excessively crowd out the space of the active ingredients.

[0018] Furthermore, the binder includes one of carboxymethyl cellulose ammonium, carboxymethyl cellulose sodium, polyvinylidene fluoride (PVDF), and polytetrafluoroethylene (PTFE), used to ensure the adhesion strength between the catalytic coating and the substrate and its own cohesive force.

[0019] Furthermore, the coating method for the slurry includes one of the following: doctor blade coating, roller coating, and dip coating, with a catalytic coating thickness of 50-150 μm. Coating thickness is a key parameter for ensuring sufficient contact between the reactant gas and the active sites. If the thickness is less than 50 μm, the total number of active sites is insufficient, resulting in limited processing capacity; if the thickness exceeds 150 μm, the utilization efficiency of the inner catalyst will decrease due to increased mass transfer resistance, and the coating is prone to cracking and peeling. Preferably, the coating thickness is 75-125 μm, a range that ensures high activity while also possessing good stability and economy.

[0020] Furthermore, the spacing between adjacent catalytic electrode plates is 2-10 mm. Studies have found that when the spacing is too small, although the electric field strength is higher, it leads to a sharp increase in gas flow resistance, making it prone to dust accumulation and blockage, and increasing the process risk of short circuits between electrodes; while if the spacing is too large, it will significantly weaken the electric field strength between the plates, resulting in insufficient driving ability for catalyst electron migration and insufficient activation of reactants, thus reducing catalytic efficiency.

[0021] The second objective of this invention is to provide a device for the electric field-enhanced catalytic oxidation of volatile organic compounds based on a molybdenum-based cathode electrode, comprising: The catalytic electrode array consists of multiple cathode catalytic electrode plates and multiple anode catalytic electrode plates arranged alternately in parallel; the spacing between adjacent catalytic electrode plates is 2-10 mm; the active component of the cathode catalytic electrode plates is molybdenum diselenide, and the active component of the anode catalytic electrode plates is p-type semiconductor material. A DC power supply is electrically connected to the catalytic electrode array. The DC power supply is configured to apply a DC voltage of 30-80V to the catalytic electrode array and cyclically perform the operation of first maintaining the current electric field polarity for 20-45 minutes, then performing a short-term reversal of the DC voltage for 2-10 seconds, and restoring the original polarity after the reversal is completed.

[0022] Furthermore, the catalytic electrode array is arranged such that the flow direction of the introduced volatile organic compound-containing gas is parallel to the surface of the catalytic electrode plate.

[0023] This invention provides a dedicated device for realizing the aforementioned efficient and stable VOCs catalytic oxidation method. The various components of the device and their parameter configurations can work synergistically to initiate a highly efficient catalytic oxidation reaction at a low voltage of 30-80V. By maintaining the polarity of the electric field in combination with short-term reversal operation, the long-term activity of the electrodes is maintained, thereby achieving efficient, stable, and low-energy purification of volatile organic compounds.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The present invention provides a field-enhanced catalytic oxidation method and apparatus for volatile organic compounds based on a molybdenum-based cathode electrode. The core of this method lies in using a 30-80V low-voltage DC electric field to drive a specifically paired molybdenum-based cathode and a p-type semiconductor anode. Under normal temperature and pressure, this method can efficiently catalyze oxygen and water molecules in ambient air to generate singlet oxygen (… 1 Reactive oxygen species, mainly O2 (such as H2O2, O2) •- This method achieves efficient and thorough oxidation and degradation of VOCs. It fundamentally avoids the inherent drawbacks of high-voltage discharge technology (such as plasma) which has high energy consumption and produces harmful byproducts such as ozone (O3). The reaction process is clean and safe, and allows for human-machine coexistence.

[0025] (2) This invention, through the synergistic effect of n-type and p-type semiconductors and the electric field enhancement effect, not only significantly improves the electron-hole separation efficiency and intrinsic catalyst activity, but also effectively desorbs contaminants on the electrode surface through periodic short-time reverse electrode operation, greatly alleviating the catalyst passivation problem and ensuring the long-term stability of the system. Meanwhile, the device has a compact structure, simple electrode manufacturing process, and the catalyst used does not contain precious metals, making the cost controllable and easy to scale up. In summary, this invention demonstrates significant advantages in energy consumption, safety, stability, and cost, and has broad application prospects in fields such as household air purification and industrial waste gas treatment. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the assembly process of the catalytic oxidation device provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the catalytic electrode array prepared according to an embodiment of the present invention; Figure 3 This is a SEM image of the cathode catalytic electrode material in Example 2 of the present invention; Figure 4 The graphs show the formaldehyde degradation curves catalyzed by the catalytic electrode in Example 1 and Comparative Example 1 of this invention. Figure 5 This is a graph showing the formaldehyde degradation catalyzed by the catalytic electrode in Example 2 of the present invention; Wherein, 1-Schematic diagram of electric field lines; 2-Electrode paste coating; 3-Metal substrate. Detailed Implementation

[0027] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] like Figure 1 and Figure 2As shown, this embodiment of the invention provides an apparatus for the electric field-enhanced catalytic oxidation of volatile organic compounds based on a molybdenum-based cathode electrode, comprising: a catalytic electrode array, consisting of multiple cathode catalytic electrode plates and multiple anode catalytic electrode plates arranged alternately in parallel; the spacing between adjacent catalytic electrode plates is 2-10 mm; the active component of the cathode catalytic electrode plates is molybdenum diselenide, and the active component of the anode catalytic electrode plates is a p-type semiconductor material; a DC power supply, electrically connected to the catalytic electrode array; the DC power supply is configured to apply a DC voltage of 30-80V to the array, and cyclically perform the operation of first maintaining the current electric field polarity for 20-45 minutes, then performing a short-term reversal of the DC voltage for 2-10 seconds, and restoring the original polarity after the reversal. The arrangement of the catalytic electrode array is configured such that the flow direction of the gas containing volatile organic compounds is parallel to the surface of the catalytic electrode plates.

[0029] The present invention provides a method for field-enhanced catalytic oxidation of volatile organic compounds based on a molybdenum-based cathode electrode. The method is carried out at room temperature and pressure, and the oxygen and water vapor required for the reaction are both derived from the polluted air to be treated. The method includes the following steps: Step 1: Prepare catalytic electrode plates. The active component of the cathode catalytic electrode plate is molybdenum diselenide; the active component of the anode catalytic electrode plate is a p-type semiconductor material. The preparation method of the catalytic electrode plate includes: coating a slurry containing the active component, conductive material, binder and solvent onto an electrode substrate, and forming a catalytic coating on the electrode substrate after drying. In the cathode catalytic electrode plate, molybdenum diselenide accounts for 60%-90% of the mass percentage of the catalytic coating; in the anode catalytic electrode plate, the p-type semiconductor material includes one or more combinations of cuprous oxide, copper oxide, nickel oxide, and cuprous sulfide; the p-type semiconductor material accounts for 60%-90% of the mass percentage of the catalytic coating; the electrode substrate includes one of copper plate, aluminum plate, nickel plate, and graphite plate, with a thickness of 0.5-2 mm; the conductive material is one or more combinations of coconut shell activated carbon, conductive carbon black, conductive graphite, carbon nanotubes, supercapacitor activated carbon, and conductive carbon fiber, with the conductive material accounting for 5%-20% of the mass percentage of the catalytic coating; the binder includes one of carboxymethyl cellulose ammonium, carboxymethyl cellulose sodium, polyvinylidene fluoride, and polytetrafluoroethylene; the coating method of the slurry includes one of doctor blade coating, roller coating, and dip coating, with a catalytic coating thickness of 50-150 μm.

[0030] Step 2: Arrange multiple cathode catalytic electrode plates and multiple anode catalytic electrode plates alternately in parallel and connect them to a DC power supply to form a catalytic electrode array; the spacing between adjacent catalytic electrode plates is 2-10 mm.

[0031] Step 3: Apply a DC voltage of 30-80V to the catalytic electrode array to generate an electric field between the electrodes, and cycle through the following steps: first maintain the current electric field polarity for 20-45 minutes, then perform a short-term reversal of the DC voltage for 2-10 seconds, and finally restore the original polarity after the reversal. Step 4: The gas containing volatile organic compounds is introduced into the catalytic electrode array in a direction parallel to the surface of the catalytic electrode plate.

[0032] The present invention will be further described below with reference to specific embodiments, but these are not intended to limit the scope of the invention.

[0033] The main parameters and variables of each embodiment of the present invention are shown in Table 1 below.

[0034] Table 1

[0035] Example 1 This embodiment provides a method for field-enhanced catalytic oxidation of volatile organic compounds based on a molybdenum-based cathode electrode, comprising the following steps: Step 1: Mix and grind 600 g of molybdenum diselenide active ingredient, 60 g of supercapacitor activated carbon, and 9 g of carboxymethyl cellulose ammonium for 20 min, then add 1200 ml of water and stir for 20 min to obtain cathode slurry; mix and grind 600 g of cuprous oxide active ingredient, 60 g of supercapacitor activated carbon, and 9 g of carboxymethyl cellulose ammonium for 20 min, then add 1200 ml of water and stir for 20 min to obtain anode slurry; coat the cathode slurry onto one side of 10 325×85×2 mm carbon plates using a roller coating method to form a catalyst coating 150 μm thick, vacuum dry at 80℃ for 24 h, then coat the other side of the 10 carbon plates with a catalyst coating of the same thickness, and vacuum dry at 80℃ for 24 h to obtain cathode catalytic electrodes; similarly, coat the anode slurry onto one side of 10 carbon plates using a roller coating method to form a catalyst coating 150 μm thick, vacuum dry, then coat the other side of the 10 carbon plates with a catalyst coating of the same thickness, and vacuum dry to obtain anode catalytic electrodes.

[0036] Step 2: Arrange 10 cathode electrodes and 10 anode electrodes alternately in a vertical parallel manner, placing them in 20 slots of an acrylic frame of 338×338×90mm. Each electrode is connected to a DC power supply through a wire. Adjacent electrode plates are the cathode and anode, respectively, and the spacing between adjacent electrode plates is 10 mm, forming a catalytic electrode array.

[0037] Step 3: Apply a 50 V DC voltage to the catalytic electrode array to generate an electric field, and cycle through the process of first maintaining the current electric field polarity for 30 minutes, then performing a short-term reversal of the DC voltage for 10 seconds, and immediately restoring the original polarity after the reversal is completed. Step 4: Air containing formaldehyde is introduced into the electrode array in a direction parallel to the electrode plates. The formaldehyde is removed by catalytic oxidation using the electric field generated by the catalytic electrode array.

[0038] Example 2 This embodiment provides a method for field-enhanced catalytic oxidation of volatile organic compounds based on a molybdenum-based cathode electrode, comprising the following steps: Step 1: Mix and grind 6 g of molybdenum diselenide active ingredient, 2 g of conductive graphite, and 2 g of polytetrafluoroethylene for 20 min, then add 10 ml of NMP solvent and mix and stir for 20 min to obtain cathode slurry; mix and grind 6 g of cuprous oxide active ingredient, 0.6 g of supercapacitor activated carbon, and 0.9 g of carboxymethyl cellulose ammonium for 20 min, then add 12 ml of water and mix and stir for 20 min to obtain anode slurry; coat the cathode slurry onto both sides of four 70×70×0.5 mm aluminum plates using a scraper method to form a 75 μm thick catalyst coating, thus obtaining four cathode catalytic electrodes; coat the anode slurry onto both sides of another four 70×70×0.5 mm aluminum plates using a scraper method to form a 75 μm thick catalyst coating, thus obtaining four anode catalytic electrodes.

[0039] Step 2: Arrange 4 cathode electrodes and 4 anode electrodes alternately in a vertical parallel manner. Each electrode is connected to a DC power supply through a wire. The two adjacent electrode plates are the cathode and anode, respectively. The distance between adjacent electrode plates is 8 mm, forming a catalytic electrode array.

[0040] Step 3: Apply a 60 V DC voltage to the catalytic electrode array to generate an electric field, and cycle through the process of first maintaining the current electric field polarity for 30 minutes, then performing a short-term reversal of the DC voltage for 10 seconds, and immediately restoring the original polarity after the reversal is completed. Step 4: Air containing formaldehyde is introduced into the electrode array in a direction parallel to the electrode plates. The formaldehyde is removed by catalytic oxidation using the electric field generated by the catalytic electrode array.

[0041] Example 3 This embodiment provides a method for field-enhanced catalytic oxidation of volatile organic compounds based on a molybdenum-based cathode electrode, comprising the following steps: Step 1: Mix and grind 8 g of molybdenum diselenide active ingredient, 1 g of coconut shell activated carbon, and 1 g of polyvinylidene fluoride for 30 min, then add 15 ml of NMP solvent and mix and stir for 20 min to obtain a slurry; mix and grind 6 g of copper oxide active ingredient, 0.6 g of supercapacitor activated carbon, and 0.9 g of carboxymethyl cellulose ammonium for 20 min, then add 12 ml of water and mix and stir for 20 min to obtain an anode slurry; coat the cathode slurry onto both sides of four 50×50×1 mm copper plates using a roller coating method to form a 150 μm thick catalyst coating, thus obtaining four cathode catalytic electrodes; coat the anode slurry onto both sides of another four 50×50×1 mm copper plates using a roller coating method to form a 150 μm thick catalyst coating, thus obtaining four anode catalytic electrodes.

[0042] Step 2: Arrange 4 cathode electrodes and 4 anode electrodes alternately in a vertical parallel manner. Each electrode is connected to a DC power supply through a wire. The two adjacent electrode plates are the cathode and anode, respectively. The distance between adjacent electrode plates is 5 mm, forming a catalytic electrode array.

[0043] Step 3: Apply a 30 V DC voltage to the catalytic electrode array to generate an electric field, and cycle through the process of first maintaining the current electric field polarity for 20 minutes, then performing a short-term reversal of the DC voltage for 5 seconds, and immediately restoring the original polarity after the reversal is completed. Step 4: Air containing toluene is introduced into the electrode array in a direction parallel to the electrode plates. The toluene is removed by catalytic oxidation using the electric field generated by the catalytic electrode array.

[0044] Example 4 This embodiment provides a method for field-enhanced catalytic oxidation of volatile organic compounds based on a molybdenum-based cathode electrode, comprising the following steps: Step 1: Mix and grind 8.5 g of molybdenum diselenide active ingredient, 0.5 g of conductive carbon fiber, and 1 g of sodium carboxymethyl cellulose for 25 min, then add 12.5 ml of deionized water and stir for 20 min to obtain a slurry; mix and grind 6 g of nickel oxide active ingredient, 0.6 g of supercapacitor activated carbon, and 0.9 g of ammonium carboxymethyl cellulose for 20 min, then add 12 ml of water and stir for 20 min to obtain an anode slurry; coat the cathode slurry onto both sides of five 60×60×2 mm graphite plates using a scraper method to form a 50 μm thick catalyst coating, thus obtaining five cathode catalytic electrodes; coat the anode slurry onto both sides of another five 60×60×2 mm graphite plates using a scraper method to form a 50 μm thick catalyst coating, thus obtaining five anode catalytic electrodes.

[0045] Step 2: Arrange 5 cathode electrodes and 5 anode electrodes alternately in a vertical parallel manner. Each electrode is connected to a DC power supply through a wire. The two adjacent electrode plates are the cathode and anode, respectively. The distance between adjacent electrode plates is 2 mm, forming a catalytic electrode array.

[0046] Step 3: Apply an 80 V DC voltage to the catalytic electrode array to generate an electric field, and cycle through the process of first maintaining the current electric field polarity for 45 minutes, then performing a short-term reversal of the DC voltage for 2 seconds, and immediately restoring the original polarity after the reversal is completed. Step 4: Air containing formaldehyde is introduced into the electrode array in a direction parallel to the electrode plates. The formaldehyde is removed by catalytic oxidation using the electric field generated by the catalytic electrode array.

[0047] Example 5 This embodiment provides a method for field-enhanced catalytic oxidation of volatile organic compounds based on a molybdenum-based cathode electrode, comprising the following steps: Step 1: Mix and grind 9 g of molybdenum diselenide active ingredient, 0.5 g of supercapacitor activated carbon, and 0.5 g of carboxymethyl cellulose ammonium for 25 min, then add 10 ml of deionized water and stir for 25 min to obtain a slurry; mix and grind 6 g of cuprous sulfide active ingredient, 0.6 g of supercapacitor activated carbon, and 0.9 g of carboxymethyl cellulose ammonium for 20 min, then add 12 ml of water and stir for 20 min to obtain an anode slurry; coat the cathode slurry onto both sides of 5 60×60×2 mm nickel plates using a scraper method to form a 75 μm thick catalyst coating, thus obtaining 5 cathode catalytic electrodes; coat the anode slurry onto both sides of another 5 60×60×2 mm nickel plates using a scraper method to form a 75 μm thick catalyst coating, thus obtaining 5 anode catalytic electrodes.

[0048] Step 2: Arrange 5 cathode electrodes and 5 anode electrodes alternately in a vertical parallel manner. Each electrode is connected to a DC power supply through a wire. The two adjacent electrode plates are the cathode and anode, respectively. The distance between adjacent electrode plates is 4 mm, forming a catalytic electrode array.

[0049] Step 3: Apply a 50 V DC voltage to the catalytic electrode array to generate an electric field, and cycle through the process of first maintaining the current electric field polarity for 40 minutes, then performing a short-term reversal of the DC voltage for 8 seconds, and immediately restoring the original polarity after the reversal is completed. Step 4: Air containing formaldehyde is introduced into the electrode array in a direction parallel to the electrode plates. The formaldehyde is removed by catalytic oxidation using the electric field generated by the catalytic electrode array.

[0050] Comparative Example 1 The electrode fabrication and electrode array assembly methods in this comparative example are the same as those in Example 1. The difference is that the cathode in this comparative example only uses a carbon plate and does not contain molybdenum-based active ingredients.

[0051] Comparative Example 2 This comparative example uses a commercial photocatalytic filter. The filter assembly method is the same as in Example 2. No current is applied to the filter, and all other experimental conditions are the same as in Example 2.

[0052] Comparative Example 3 The difference between this comparative example and Example 2 is that a short-time polarity reversal operation was not performed. The specific method includes the following steps: Step 1: Mix and grind 6 g of molybdenum diselenide active ingredient, 2 g of conductive graphite, and 2 g of polytetrafluoroethylene for 20 min, then add 10 ml of NMP solvent and mix and stir for 20 min to obtain cathode slurry; mix and grind 6 g of cuprous oxide active ingredient, 0.6 g of supercapacitor activated carbon, and 0.9 g of carboxymethyl cellulose ammonium for 20 min, then add 12 ml of water and mix and stir for 20 min to obtain anode slurry; coat the cathode slurry onto both sides of four 70×70×0.5 mm aluminum plates using a scraper method to form a 75 μm thick catalyst coating, thus obtaining four cathode catalytic electrodes; coat the anode slurry onto both sides of another four 70×70×0.5 mm aluminum plates using a scraper method to form a 75 μm thick catalyst coating, thus obtaining four anode catalytic electrodes.

[0053] Step 2: Arrange 4 cathode electrodes and 4 anode electrodes alternately in a vertical parallel manner. Each electrode is connected to a DC power supply through a wire. The two adjacent electrode plates are the cathode and anode, respectively. The distance between adjacent electrode plates is 8 mm, forming a catalytic electrode array.

[0054] Step 3: Apply a 60 V DC voltage to the catalytic electrode array to generate an electric field. During the application of the electric field, keep the polarity of the cathode and anode constant.

[0055] Step 4: Air containing formaldehyde is introduced into the electrode array in a direction parallel to the electrode plates. The formaldehyde is removed by catalytic oxidation using the electric field generated by the catalytic electrode array.

[0056] Application performance testing In all the above embodiments and comparative examples, the concentration of organic pollutant gas in the air was set to 30 ppm, and the introduction time was set to 120 min. The concentration of organic pollutant gas after treatment in each embodiment and comparative example was tested, and the removal rate was calculated, as shown in Table 2 below.

[0057] Table 2

[0058] As can be seen from the above table, The electric field-enhanced catalytic oxidation method for volatile organic compounds based on a molybdenum-based cathode electrode provided in Examples 1-5 of this invention exhibits highly efficient removal capabilities for various types of volatile organic compounds (VOCs) such as formaldehyde and toluene, with removal rates exceeding 85.0% within a 120-minute test. Furthermore, data from Examples 1, 2, and 5 show that under a moderate DC voltage of 50-60V, combined with a 30-40 minute reversal interval and a short 8-10 second reversal, an optimal synergistic effect is achieved, resulting in a formaldehyde removal rate exceeding 90%. This indicates that within this parameter window, the electric field strength is sufficient to efficiently drive the catalytic reaction, while the reversal operation promptly restores electrode activity, thereby maximizing the catalytic oxidation performance.

[0059] When using a carbon plate as a catalytic electrode in Comparative Example 1, the formaldehyde removal rate in the outflow gas was only 5.1% after 120 minutes, indicating a weak ability to continuously degrade and remove formaldehyde.

[0060] Comparative Example 2, using a commercially available photocatalytic filter under the same testing conditions, achieved a formaldehyde removal rate of 49.5% after 120 minutes, significantly lower than Example 2 of this invention (91.5%). This result highlights the significant advantages of the electric field-enhanced catalytic oxidation technology employed in this invention compared to traditional photocatalytic technologies in treating low-concentration VOCs.

[0061] In Comparative Example 3, without periodic reversal operations, the removal rate decreased to 65.8%, significantly lower than that of Example 2 (91.5%). This strongly demonstrates that short-term reversal operations are crucial for reversing or mitigating electrode polarization, removing accumulated intermediate products from the electrode surface, and preventing the occupancy or poisoning of catalyst active sites. This operation is key to maintaining the long-term, efficient, and stable operation of the system.

[0062] In summary, this invention utilizes the synergistic effect of molybdenum diselenide (an n-type semiconductor material) and p-type semiconductor materials to efficiently catalyze the reaction of oxygen and water molecules under a low-voltage electric field, generating a strong oxidizing substance dominated by singlet oxygen, thus completely degrading VOCs. Periodic short-time electrode reversal operations prevent electrode passivation, ensuring long-term operational stability. This invention has the advantages of low energy consumption, no ozone byproducts, safety, reliability, and long service life, making it suitable for both household and industrial air purification applications.

[0063] The above are merely preferred embodiments of the present invention and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should recognize that any equivalent substitutions and obvious changes made based on the content of this specification should be included within the protection scope of the present invention.

Claims

1. A method for field-enhanced catalytic oxidation of volatile organic compounds based on a molybdenum-based cathode electrode, characterized in that, Includes the following steps: A catalytic electrode plate is prepared, wherein the active component of the cathode catalytic electrode plate is molybdenum diselenide; and the active component of the anode catalytic electrode plate is a p-type semiconductor material; wherein the p-type semiconductor material includes one or more combinations of cuprous oxide, copper oxide, nickel oxide, and cuprous sulfide. Multiple cathode catalytic electrode plates and multiple anode catalytic electrode plates are arranged alternately in parallel and connected to a DC power supply to form a catalytic electrode array. A DC voltage of 30-80V is applied to the catalytic electrode array to generate an electric field between the electrodes, and the operation is performed cyclically: first, the current electric field polarity is maintained for 20-45 minutes, then the DC voltage is reversed for 2-10 seconds, and the original polarity is restored after the reversal is completed. A gas containing volatile organic compounds is introduced into the catalytic electrode array in a direction parallel to the surface of the catalytic electrode plates.

2. The method according to claim 1, characterized in that, The method for preparing the catalytic electrode plate includes: coating a slurry containing active ingredients, conductive substances, binders and solvents onto an electrode substrate, and then drying it to form a catalytic coating on the electrode substrate.

3. The method according to claim 2, characterized in that, In the cathode catalytic electrode plate, molybdenum diselenide accounts for 60%-90% of the mass percentage of the catalytic coating.

4. The method according to claim 2, characterized in that, In the anode catalytic electrode plate, p-type semiconductor material accounts for 60%-90% of the mass percentage of the catalytic coating.

5. The method according to claim 2, characterized in that, The electrode substrate includes one of copper plate, aluminum plate, nickel plate, and graphite plate, with a thickness of 0.5-2 mm.

6. The method according to claim 2, characterized in that, The conductive material is one or more of coconut shell activated carbon, conductive carbon black, conductive graphite, carbon nanotubes, and conductive carbon fibers, and the conductive material accounts for 5%-20% of the mass percentage of the catalytic coating.

7. The method according to claim 2, characterized in that, The coating method of the slurry includes one of the following: doctor blade coating, roller coating, and dip coating, and the thickness of the catalytic coating is 50-150 μm.

8. The method according to claim 1, characterized in that, The spacing between adjacent catalytic electrode plates is 2-10 mm.

9. A device for the electric field-enhanced catalytic oxidation of volatile organic compounds based on a molybdenum-based cathode electrode, characterized in that, include: The catalytic electrode array is composed of multiple cathode catalytic electrode plates and multiple anode catalytic electrode plates arranged alternately in parallel; the spacing between adjacent catalytic electrode plates is 2-10 mm; the active component of the cathode catalytic electrode plate is molybdenum diselenide, and the active component of the anode catalytic electrode plate is a p-type semiconductor material; the p-type semiconductor material includes one or more combinations of cuprous oxide, copper oxide, nickel oxide, and cuprous sulfide. A DC power supply is electrically connected to the catalytic electrode array. The DC power supply is configured to apply a DC voltage of 30-80V to the catalytic electrode array and cyclically perform the operation of first maintaining the current electric field polarity for 20-45 minutes, then performing a short-term reversal of the DC voltage for 2-10 seconds, and restoring the original polarity after the reversal is completed.

10. The apparatus according to claim 9, characterized in that, The catalytic electrode array is arranged such that the flow direction of the introduced volatile organic compound-containing gas is parallel to the surface of the catalytic electrode plate.

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