Thermal shock induced catalytic electrode, preparation method and wastewater treatment application thereof

Abstract

This invention discloses a thermal shock-induced catalytic electrode, its preparation method, and its application in wastewater treatment, belonging to the field of wastewater treatment technology. The catalytic electrode comprises a titanium metal substrate and a mixed metal oxide catalytic layer formed on the surface of the titanium metal substrate. The mixed metal oxide catalytic layer has a hydroxylation-rich surface, high specific surface area, and large pore volume, and its microstructure is a uniform mud-crack-like porous structure containing nanoscale grains. The preparation method includes first laser shock strengthening of the titanium metal substrate to form a mesoscale array structure; then loading the mixed metal oxide precursor using an immersion-pulling-space flow method; subsequently performing annealing; rapidly immersing the annealed electrode in a hydrogen peroxide solution for thermal shock quenching; and finally performing low-temperature tempering to eliminate internal stress and reduce resistance. The catalytic electrode of this invention achieves a balance between catalytic activity, conductivity, and stability, and its preparation process is simple and easy for large-scale industrial production.

Description

Technical Field

[0001] This invention belongs to the field of water treatment and electrocatalysis technology, specifically relating to a thermal shock induced catalytic electrode, its preparation method, and its application in wastewater treatment. Background Technology

[0002] The rapid pace of industrialization and urbanization has led to severe challenges globally, including climate change, water quality deterioration, and water scarcity. Industrial wastewater from industries such as pharmaceuticals, textiles, chemicals, and petrochemicals contains large amounts of recalcitrant or biodegradable organic pollutants (such as natural organic matter, industrial chemicals, pharmaceuticals, and pesticides), causing serious negative impacts on the ecological environment. Therefore, developing efficient and sustainable wastewater treatment technologies has become an urgent technical problem to be solved.

[0003] Electrocatalytic oxidation technology using mixed metal oxides has broad market prospects in the water treatment field due to its advantages such as high treatment efficiency, simple operation, simple equipment manufacturing, no need for chemical reagents, no secondary pollution, and thorough degradation. The electrode, as the core component of the electrocatalytic oxidation reactor, has a catalytic material layer supported on its metal substrate surface, which is the site of the electrocatalytic oxidation reaction and directly determines the overall performance of the water treatment process. Existing technologies mostly optimize catalytic performance through strategies such as precisely controlling the atomic structure and crystal facet exposure of the catalyst surface, modulating surface functional groups and active sites, and regulating interfacial effects and carrier-catalyst coupling. However, these strategies suffer from problems such as complex synthesis processes, laborious post-processing, harsh reaction conditions, and the potential for environmental pollutants, which greatly limit their large-scale industrial application.

[0004] In recent years, heat treatment has been considered an important means of regulating the structure and optimizing the performance of mixed metal oxide electrodes, as it can affect the crystallinity, bonding strength, electronic structure, and catalytic performance of the coating. For example, patent CN120443217A proposes a process of directional metal substrate spraying of precursors combined with heat treatment-rapid quenching (liquid nitrogen quenching, ice-water quenching, or gradient temperature-controlled cooling) to drive atomic-level solid solution reconstruction using array confinement effect, forming a catalytically active layer with heterogeneous interface coupling, thereby improving the mechanical stability and reaction kinetics of the electrode. However, this heat treatment-rapid quenching process has significant drawbacks: it enhances electron scattering of the metal substrate, leading to increased resistance and decreased conductivity; it also causes array confinement collapse of the catalytic layer, lattice distortion, and increased dislocation density, thereby reducing catalytic activity and ultimately affecting the overall efficiency of the electrode in water treatment and generating disinfection byproducts.

[0005] Therefore, there is an urgent need to develop a catalytic electrode that can balance catalytic activity, conductivity and stability, and whose preparation process is simple and easy to scale up for industrial production, in order to overcome the shortcomings of existing technologies. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a thermal shock induced catalytic electrode, its preparation method, and its application in wastewater treatment. By using high-throughput screening of quenching media and thermal shock induction conditions, a thermal shock induced catalytic electrode of mixed metal oxides that balances activity, conductivity, and stability is constructed. The invention regulates the grain size, surface hydroxylation, defect concentration, and phase composition of the mesoscale surface solid solution mixed metal oxides, as well as the exposure of high-density active sites, reducing the poor conductivity caused by quench-induced residual stress hindering electron migration. Furthermore, it regulates the uniform porous mud-crack structure of the macroscale catalytic layer, thereby increasing the electrochemical active surface area, improving catalyst utilization, promoting rapid removal of evolved gases, enhancing mass transfer, and improving the diffusion and transport of pollutants, electrolytes, and other reactants and products in the water treatment process. It also improves the overall conductivity of the electrode and the contact between interfaces of the catalytic layer. Moreover, the process is simple and can achieve large-scale industrial-scale preparation.

[0007] A first aspect of the present invention is to provide a thermal shock-induced catalytic electrode, the catalytic electrode comprising: Titanium metal substrate; And a mixed metal oxide catalyst layer formed on the surface of the titanium metal substrate; The mixed metal oxide catalyst layer has a hydroxylated surface, high specific surface area and large pore volume, and its microstructure is a uniform mud-crack-like porous structure containing nanoscale grains. The hydroxyl density on the surface of the mixed metal oxide catalyst layer is greater than 2.40 × 10⁻⁶. 15 pcs / cm²; The specific surface area of ​​the mixed metal oxide catalyst layer is greater than 26.00 m² / g; The total pore volume of the mixed metal oxide catalyst layer surface is greater than 0.08 cm³ / g, and the pore size ranges from ~95.46 to 98.77 nm. The measurement conditions are relative pressure P / Po = 0.98.

[0008] In a first aspect of the present invention, as a preferred embodiment, the metal element in the mixed metal oxide catalyst layer is selected from two or more of ruthenium, iridium, cobalt, tin, tantalum, platinum, zinc, tungsten, strontium, titanium, niobium, molybdenum, cerium, rhodium, and palladium; the size of the nanoscale grains is 8-20 nm.

[0009] A second aspect of the present invention provides a method for preparing a thermal shock-induced catalytic electrode, comprising the following steps: Step S1: Perform laser shock peening treatment on the surface of the titanium metal substrate to form a titanium metal substrate with a mesoscale array structure; Step S2: Using the dip-pull-space slope flow method, a mixed metal oxide solid solution precursor is loaded onto the titanium metal substrate to obtain a titanium-based mixed metal oxide electrode; Step S3: Anneal the titanium-based mixed metal oxide electrode; Step S4: Remove the annealed electrode at a certain temperature and quickly immerse it in a quenching medium for thermal shock quenching. Step S5: Perform low-temperature tempering on the quenched electrode and cool it to room temperature in the furnace to obtain the catalytic electrode.

[0010] In a second aspect of the present invention, as a preferred embodiment, step S1 specifically includes the following steps: Pre-treat the surface of the titanium metal substrate; An energy-absorbing layer is coated onto the pretreated surface; A constraint layer is covered on the energy absorption layer; Using a short-pulse laser beam, laser shock peening treatment is performed on the surface of a titanium metal substrate covered with the energy absorption layer and the constraint layer through array scanning or beam shaping. Simultaneously, a residual compressive stress layer and a regularly arranged microstructure array are formed on the surface, namely the mesoscale array substrate. Remove the residual absorber and constraint layers to complete the preparation.

[0011] In a second aspect of the present invention, as a preferred embodiment, the parameters of the laser shock strengthening process in step S1 are: laser ring spacing 0.2-0.8 mm, line spacing 0.03-0.1 mm, and processing frequency not less than 80 kHz.

[0012] In a second aspect of the present invention, as a preferred embodiment, the annealing conditions in step S3 are: holding at 500-550°C for 1 hour, with a heating rate of 5-10°C / minute.

[0013] In a second aspect of the present invention, as a preferred embodiment, in step S4, the quenching medium is an aqueous solution of hydrogen peroxide with a concentration of 1-8 wt%.

[0014] In a second aspect of the present invention, as a preferred embodiment, the quenching temperature in step S4 is 405-465°C.

[0015] In a second aspect of the present invention, as a preferred embodiment, the tempering conditions in step S5 are: holding at 280-350°C for 1 hour.

[0016] A third aspect of the present invention is to provide an application of a thermal shock induced catalytic electrode in wastewater treatment or green disinfection scenarios.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The present invention uses laser shock substrate, dip-pull-space slope flow method to load metal oxide solid solution, and annealing + quenching + tempering process to treat the surface structure morphology of electrode to prepare thermal shock induced catalytic electrode. The process is simple and efficient, significantly reduces cost, and is easy to achieve large-scale industrial preparation. It has strong catalytic activity, conductivity, stability and corrosion resistance and takes into account the balance of the three. (2) The mixed metal oxide thermal shock induced catalytic electrode prepared by the present invention has an expanded probability distribution of wide cracks on the outer surface of the catalytic layer and provides a smooth island structure on the inner surface during the tempering and quenching process, which significantly increases the specific surface area of ​​the catalytic layer; the formed grains are refined and uniform, exposing more effective active sites, significantly increasing the oxygen evolution overpotential and significantly decreasing the chlorine evolution overpotential, which is conducive to the diffusion of evolved gas during the reaction, improves the catalyst utilization rate, and enhances the mass transfer effect of the reaction process. (3) In addition to the conventional function of temperature control and rapid cooling to regulate morphology and structure, the quenching medium screened in this invention can also generate active oxygen species during rapid cooling, optimize the oxidation state of the catalyst, enhance the activity of chlorine evolution reaction (CER), decompose surface adsorbed pollutants, clean the electrode surface, and may expose more active sites. (4) The present invention uses low-temperature tempering to eliminate quenching stress, reduce lattice distortion, promote the precipitation of supersaturated solute atoms (such as carbon), reduce solid solution electron scattering, and reduce the resistivity of electrode substrate and catalyst layer by about 10-35%, while maintaining catalytic activity. (5) This invention uses H2O2 room temperature short-time treatment combined with subsequent annealing and tempering processes to repair coating defects. It can also be used to regenerate old electrodes and improve activity and service life.

[0018] (6) The catalytic layer of the electrode of the present invention has a hydroxyl-rich surface. Hydroxyl groups, as key active species, can significantly improve the efficiency of electrocatalytic oxidation reaction, especially for wastewater containing recalcitrant organic pollutants. At the same time, the catalytic layer is a uniform mud-crack-like porous structure containing nano-sized crystals below 20 nm, with an ultra-large specific surface area, which can expose a large number of active sites and further enhance the catalytic performance. Attached Figure Description

[0019] Figure 1 This is a magnified schematic diagram of a portion of the titanium metal substrate according to Embodiment 1 of the present invention. The magnification is 500.

[0020] Figure 2 This is a comparison chart of COD degradation rates when quenching with hydrogen peroxide aqueous solutions of different concentrations according to the present invention.

[0021] Figure 3-1 XRD diffraction patterns of the coatings of the AQT electrode and the NA electrode; Figure 3-2 The Ir4f spectrum of the XPS plot for the AQT electrode; Figure 3-3 The O1s spectrum of the XPS plot for the AQT electrode; Figure 3-4 The Ir4f spectrum is the XPS plot of the NA electrode; Figure 3-5 The O1s spectrum is the XPS plot of the NA electrode.

[0022] Figure 3-6a 3-6b are FESEM images of the AQT electrode at different magnifications; Figure 3-7a 3-7b are FESEM images of the NA electrode at different magnifications; Figure 3-8 Comparison of nitrogen adsorption-desorption isotherms of the coatings of AQT and NA electrodes.

[0023] Figure 3-9 A comparison diagram of the pore size distribution of the coatings for the AQT electrode and the NA electrode (BJH).

[0024] Figure 4-1a This is a cyclic voltammetry curve collected by the AQT electrode in 1.0 M NaCl electrolyte.

[0025] Figure 4-1b This is a cyclic voltammetry curve collected by the NA electrode in 1.0 M NaCl electrolyte.

[0026] Figure 4-2 Linear sweep voltammetry curves for the AQT electrode and the NA electrode.

[0027] Figure 4-3 The diagram shows the Tafel slope curves for the AQT electrode and the NA electrode.

[0028] Figure 4-4 The images show the electrochemical impedance spectroscopy of the AQT electrode and the NA electrode.

[0029] Figure 4-5 This is a bar chart comparing the surface hydroxylation density (Boehm titration) of the AQT electrode and the NA electrode.

[0030] Figure 4-6 This is a bar chart comparing the single-site transition frequency (TOF) of the AQT electrode and the NA electrode.

[0031] Figure 4-7 A comparison of reaction kinetic curves for treating low-concentration dyeing and printing wastewater using AQT and NA electrodes, respectively.

[0032] Figure 5-1 Comparison of the degradation effects of electrodes treated with different quenching media on dyeing and printing wastewater.

[0033] Figure 5-2 The graph shows the relationship between COD and removal rate of dyeing and printing wastewater electrocatalytically degraded by AQT and NA electrodes and time.

[0034] Figure 5-3 A comparison chart showing the energy consumption of AQT electrode and NA electrode for treating dyeing and printing wastewater.

[0035] Figure 5-4 This is a comparison of the time-varying changes in chloride ion consumption and chlorate ion generation between the AQT electrode and the NA electrode.

[0036] Figure 5-5 This is a comparison of the average current efficiency of electrocatalytic oxidation between the AQT electrode and the NA electrode.

[0037] Figure 5-6 The graph shows the performance changes of a reactor using AQT electrodes when treating actual dyeing and printing wastewater. Detailed Implementation

[0038] The invention will now be further described with reference to the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments. Unless otherwise specified, the materials and equipment used in this embodiment are commercially available. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0039] A first aspect of the present invention is to provide a thermal shock-induced catalytic electrode, the catalytic electrode comprising: Titanium metal substrate; And a mixed metal oxide catalyst layer formed on the surface of the titanium metal substrate; The catalyst layer has a hydroxylated surface, high specific surface area and large pore volume, and its microstructure is a uniform mud-crack-like porous structure containing nanoscale grains. The hydroxyl density on the surface of the mixed metal oxide catalyst layer is greater than 2.40 × 10⁻⁶. 15 pcs / cm²; The specific surface area of ​​the mixed metal oxide catalyst layer is greater than 26.00 m² / g; The total pore volume of the mixed metal oxide catalyst layer surface is greater than 0.08 cm³ / g, and the pore size ranges from ~95.46 to 98.77 nm. The measurement conditions are relative pressure P / Po = 0.98.

[0040] Furthermore, the metal element in the mixed metal oxide catalyst layer is selected from two or more of the following: ruthenium (Ru), iridium (Ir), cobalt (Co), tin (Sn), tantalum (Ta), platinum (Pt), zinc (Zn), tungsten (W), strontium (Sr), titanium (Ti), niobium (Nb), molybdenum (Mo), cerium (Ce), rhodium (Rh), and palladium (Pd).

[0041] Furthermore, the size of the nanoscale crystals is 8-20 nm. Crystals in this size range can significantly increase the specific surface area of ​​the catalyst layer, expose more active sites, and improve catalytic efficiency.

[0042] The preparation method of the above-mentioned catalytic electrode includes the following steps: Step S1: Perform laser shock peening treatment on the surface of the titanium metal substrate to form a titanium metal substrate with a mesoscale array structure containing residual compressive stress; Specifically, step S1 includes the following steps: pre-treating the surface of the titanium metal substrate; coating the pre-treated surface with an energy absorption layer; covering the energy absorption layer with a constraint layer; using a short-pulse laser beam, through array scanning or beam shaping, performing laser shock peening treatment on the surface of the titanium metal substrate covered with the energy absorption layer and the constraint layer, simultaneously forming a residual compressive stress layer and a regularly arranged microstructure array on the surface, i.e., the mesoscale array substrate; removing the residual absorption layer and constraint layer to complete the preparation.

[0043] The parameters for laser shock peening are: laser ring spacing 0.2-0.8 mm, line spacing 0.03-0.1 mm, and processing frequency not less than 80 kHz. The shock wave causes plastic deformation of the titanium substrate surface, resulting in residual compressive stress, grain refinement, and reduced surface defects. This is achieved in the presence of Cl... - The medium and surface compressive stress greatly hinder the initiation and propagation of corrosion cracks, significantly extending the service life; the formation of the titanium metal substrate with mesoscale array structure significantly improves the surface roughness, effectively increases the surface area of ​​the electrode, and has a larger solid solution loading surface, improving mass transfer efficiency and promoting electrocatalytic oxidation efficiency.

[0044] Step S2: Using the dip-pull-space slope flow method, a mixed metal oxide solid solution precursor is loaded onto the titanium metal substrate to obtain a titanium-based mixed metal oxide electrode. During the dip-pull process, the dip speed, precursor concentration and dip number can be adjusted to ensure that the precursor is uniformly loaded on the substrate surface, laying the foundation for the subsequent formation of a uniform catalytic layer.

[0045] Step S3: Anneal the titanium-based mixed metal oxide electrode. The annealing conditions are: holding at 500-550℃ for 1 hour, with a heating rate of 5-10℃ / min. These annealing conditions promote the decomposition and crystallization of the precursor, forming a stable mixed metal oxide solid solution structure.

[0046] Step S4: The annealed electrode is removed at a certain temperature and quickly immersed in a quenching medium for thermal shock quenching. The quenching medium is a 1-8 wt% hydrogen peroxide aqueous solution, and the quenching temperature is 405-465℃. Using the hydrogen peroxide aqueous solution as the quenching medium, under thermal shock, on the one hand, it can induce the formation of a uniform, mud-crack-like porous structure in the catalyst layer; on the other hand, the active oxygen species generated by the decomposition of hydrogen peroxide can combine with the metal sites of the catalyst layer, achieving surface hydroxylation. The specific quenching temperature range can prevent the catalyst layer from detaching due to excessive stress caused by sudden temperature changes.

[0047] Step S5: Perform low-temperature tempering on the quenched electrode and cool it to room temperature in the furnace to obtain the catalytic electrode; wherein, the tempering conditions are: holding at 280-350℃ for 1 hour. Low-temperature tempering can effectively eliminate the internal stress generated during quenching, further stabilize the microstructure of the catalytic layer, and improve the mechanical stability and long-term operational reliability of the electrode.

[0048] An application of a thermal shock-induced catalytic electrode in wastewater treatment, wherein the wastewater contains recalcitrant organic pollutants, chloride ions, or sulfate ions. When treating this type of wastewater, the hydroxyl-rich surface of the electrode mediates an efficient oxidation reaction pathway, rapidly degrading the recalcitrant organic pollutants; simultaneously, the presence of chloride or sulfate ions further promotes the electrocatalytic oxidation reaction, improving treatment efficiency. This electrode can be widely used in the treatment of wastewater containing recalcitrant pollutants, such as pharmaceutical wastewater, dyeing and printing wastewater, and chemical wastewater.

[0049] The following are some embodiments listed in this application, which further illustrate this application.

[0050] Example 1 A method for preparing a thermal shock-induced catalytic electrode includes the following steps: S1. Pretreatment and laser shock strengthening of titanium substrate A piece of industrial pure TA2 titanium plate with dimensions of 50mm×80mm×1mm was selected as the substrate.

[0051] Pre-treatment of titanium plates: mechanically polish the surface with 80-grit, 400-grit, and 800-grit sandpaper in sequence until it is bright and free of oxide scale. Then, ultrasonically clean it in acetone and anhydrous ethanol for 15 minutes in sequence to remove oil stains. Rinse with deionized water and air dry.

[0052] A thin layer of black paint is uniformly coated onto the surface of the treated titanium plate as an energy absorption layer.

[0053] A layer of flowing water is applied over the black paint as a constraint layer.

[0054] A nanosecond pulsed laser was used to perform laser shock peening on the surface of a titanium plate. The laser parameters were set as follows: wavelength 1064 nm, pulse energy 8 J, spot diameter 3 mm, ring spacing 0.5 mm, line spacing 0.08 mm, and processing frequency 100 kHz. An array-based scanning path was used to cover the entire surface.

[0055] After treatment, the substrate was bathed in oxalic acid at 80°C for 1 hour, then sonicated in pure water for 10 minutes and washed with pure water. After drying in a drying oven at 60°C, it was stored in ethanol to obtain a titanium metal substrate with a mesoscale array structure having residual compressive stress.

[0056] Please refer to Figure 1 A mesoscale array structure is formed on the surface of the titanium metal substrate.

[0057] S2, Catalyst layer loading and heat treatment Preparation of coating solution: The solvent was prepared by mixing isopropanol and 37wt% concentrated hydrochloric acid in a ratio of 20:1 and sonicating for 10 min. The precursor metal mixture used to coat the pretreated Ti metal plate was prepared by dissolving RuCl3·3H2O and IrCl3·3H2O in the aforementioned mixed solvent at a molar ratio of Ru:Ir=3:1 and mixing them again. The mixture was then sonicated at 40℃ and 45kHz for 1 h to ensure uniform mixing and prepare the coating solution.

[0058] Precursor loading: The titanium substrate was immersed in the coating solution using an immersion-pull-spatial flow method, and then pulled out at a uniform speed of 120 mm / min. The electrode orientation was adjusted, and the liquid film was ensured to be uniform by spatial flow under gravity. It was then dried at 80°C for 10 minutes. This immersion-drying process was repeated 8-10 times until the catalyst loading reached approximately 1.8 mg / cm².

[0059] S3. Annealing treatment: Place the electrode loaded with the precursor into a muffle furnace and heat it from room temperature to 500-550°C at a heating rate of 8°C / min. Then, anneal it at 500-550°C for 1 hour and then slowly cool it down to 445°C in the furnace.

[0060] S4. Quenching treatment: Quickly remove the electrode from the muffle furnace at 445℃ and immediately immerse its entire effective surface in a beaker containing a 3wt% hydrogen peroxide aqueous solution at room temperature for 15 minutes. A large number of tiny bubbles can be observed on the electrode surface.

[0061] S5. Tempering treatment: The quenched electrode is placed in another muffle furnace and subjected to low-temperature tempering treatment at 300°C for 1 hour, followed by furnace cooling to room temperature. Finally, the thermal shock induced catalytic electrode of the present invention is obtained, denoted as AQT, AQT electrode, or AQT-RuO2-IrO2 electrode.

[0062] Example 2: Effect of quenching medium concentration: The preparation process was the same as in Example 1, except that the concentration of the quenching medium in step 3 was changed to investigate its effect: Example 2-1: Quenching was performed using a 5wt% aqueous solution of hydrogen peroxide.

[0063] Example 2-2: Quenching was performed using a 1 wt% aqueous solution of hydrogen peroxide.

[0064] Reference Figure 2 In experiments using three concentrations (1%, 3%, and 5%) of hydrogen peroxide aqueous solution, the electrode quenched with a 3 wt% hydrogen peroxide aqueous solution showed the best COD degradation effect within 15 minutes.

[0065] Comparative Example 1: Conventional heat-treated electrode The preparation process is the same as in Example 1, but the quenching and tempering treatment in step 3 is omitted. That is, after the electrode is annealed at 500-550℃, it is directly cooled to room temperature in the furnace. The resulting electrode is denoted as NA, NA electrode, or NA-RuO2-IrO2 electrode.

[0066] Comparative Example 2: Different Quenching Media The preparation process is the same as in Example 1, but the quenching medium in step 3 is replaced with: Comparative Example 2-1: Ice-water mixture (0°C).

[0067] Comparative Example 2-2: Liquid nitrogen.

[0068] Comparative Examples 2-3: No quenching was performed.

[0069] Performance Testing and Results The following test data and charts demonstrate the superior performance of this invention.

[0070] Please refer to Figure 3-1 XRD diffraction patterns of the coatings of the AQT electrode and the NA electrode.

[0071] The figure shows sharp Bragg diffraction peaks observed in the XRD pattern on the Ti / RuO2-IrO2 anode surface, consistent with the patterns in the tetragonal rutile oxide IrO2 (JPCD: 15-0870) and RuO2 (JPCD: 40-1290) databases. The three characteristic peaks at 28.1°, 35.3°, and 54.1° are attributed to the Ti diffraction peaks of the (110), (101), and (211) planes of Ru / IrO2, respectively. The presence of these peaks can be explained by the typical mud-crack morphology commonly found in thermal decomposition electrodes, which exhibits small cracks on the coating with a relatively low coating thickness. The XRD peaks shift to the left, indicating an increase in the lattice constant. Due to lattice expansion, O loss leads to relaxation, resulting in a more stable crystal structure and increased crystallinity.

[0072] Depend on Figure 3-1 It can be seen that the unit cell parameters of the mixed oxide and metallic phases observed in the diffraction patterns were evaluated. The calculated lattice parameters show that the unit cell parameter a of AQT-RuO2-IrO2 is slightly smaller (-3.895 Å), while that of NA-RuO2-IrO2 is slightly larger (-3.897 Å), with the volume difference increasing by approximately 0.35% within the studied composition range. The grain size of AQT-RuO2-IrO2 is smaller (8-20 nm after Rietveld refinement), while the grain size of NA-RuO2-IrO2 (20-25 nm after Rietveld refinement) increases by more than 30% compared to AQT-RuO2-IrO2, and the microstrain decreases by 30%.

[0073] Please refer to Figure 3-2 The Ir4f spectrum of the XPS plot of the AQT electrode; Please refer to Figure 3-3 O1s spectrum of XPS plot of AQT electrode; Please refer to Figure 3-4 The Ir4f spectrum of the XPS image of the NA electrode; Please refer to Figure 3-5 O1s spectrum of XPS plot of NA electrode.

[0074] In the Ir4f spectrum of the XPS plot, the Ir4f7 / 2 peak at the AQT electrode (61.1 eV) is significantly shifted by -0.8 eV compared to the NA electrode (61.9 eV), indicating a weakening of electron binding and an increase in electron density (enhanced shielding), approaching the metallic state (Ir). 0 (Or slightly oxidized) the effective nuclear charge sensed by the measured Ir4f electrons decreases, and the binding energy shifts negatively. During quenching, H2O2 decomposes rapidly to generate ·OH and HO2·, releasing heat, in Ir 4+ Surface transformation to Ir 3+–OH, while lattice oxygen is “removed” to generate O2. During the AQT process, the high-temperature Ti / RuO2-IrO2 is subjected to a sudden impact of 3wt% H2O2 at room temperature, causing rapid contraction of the surface layer, resulting in lattice distortion and polycrystalline formation on the RuO2-IrO2 surface.

[0075] The presence of peaks at 531.1-532.2 eV in the O1s spectrum of the XPS pattern confirms the presence of Ir-OH in the ruthenium oxide iridium coating. By performing peak fitting on the peak areas of lattice oxygen (Ir-O), hydroxyl oxygen (Ir-OH), adsorbed water, or surface carbon and oxygen species in the O1s spectrum (525-540 eV), the area ratio of hydroxyl oxygen (Ir-OH) was identified. The AQT-Ti / RuO2-IrO2 (39.57%) increased by 8.02% compared to NA-Ti / RuO2-IrO2 (31.55%). Combined with the aforementioned changes in the Ir4f spectrum, it was further determined that hydroxylation was created on the electrode surface, indicating that quenching and tempering with 3wt% H2O2 induces hydroxylation on the electrode surface.

[0076] Please refer to Figure 3-6a 3-6b represent different magnifications ( Figure 3-6a 20,000 times Figure 3-6b FESEM image of the AQT electrode at 100,000x magnification; Please refer to Figure 3-7a 3-7b represent different magnifications ( Figure 3-7a 20,000 times Figure 3-7b FESEM image of the NA electrode at 100,000x magnification; SEM high-magnification images show that the surface morphology of the AQT-Ti / RuO2-IrO2 electrode has finer grains (14.55-18.57 nm), while the surface grains of the NA-Ti / RuO2-IrO2 electrode are approximately 23.11-27.27 nm. The analytical results of the two are very close, which indicates that the morphology of Ti / RuO2-IrO2 is largely affected by quenching-tempering, exposing more fresh, well-formed active crystal faces.

[0077] Please refer to Figure 3-8 Comparison of nitrogen adsorption-desorption isotherms of coatings for AQT and NA electrodes. Please refer to Figure 3-9 Comparison of pore size distribution of coatings for AQT and NA electrodes (BJH). Nitrogen adsorption-desorption isotherms show that the AQT-Ti / RuO2-IrO2 electrode coating has a higher BET specific surface area (26.07 m² / g), which is significantly higher than that of the NA-Ti / RuO2-IrO2 electrode coating (12.87 m² / g). This further confirms that the improved heat treatment process, "annealing-quenching-tempering," can produce electrode coatings with high specific surface areas.

[0078] Pore ​​size distribution analysis revealed that both samples exhibited type IV isotherms with a distinct H3-type hysteresis loop, indicating the presence of mesoporous structures with relatively open pore structures (slit pores or planar pores). The total pore volume (P / P0=0.98) and average pore size of AQT-Ti / RuO2-IrO2 increased by 38.77% and decreased by 31.47% compared to NA-Ti / RuO2-IrO2, respectively. AQT-Ti / RuO2-IrO2 primarily consists of mesopores, with some contribution from micropores. The overall pore structure is more open, fine, and dense, with a pore size range of 2-4 nm. In the high-pressure region (P / P0>0.9), the adsorption capacity is significantly higher than that of NA-Ti / RuO2-IrO2, indicating a larger pore volume and a more developed pore structure, providing more contact interfaces and exhibiting higher adsorption capacity. The large specific surface area and porous characteristics jointly promote the high exposure of active sites and the rapid transfer of electrons and ions, thereby improving interfacial reactivity and catalytic performance, and enhancing mass transfer performance.

[0079] In summary, the systematic changes in grain size, BET specific surface area, mesopore size, spacing, and topology of the AQT-Ti / RuO2-IrO2 electrode can reveal the contribution of mass transport to the observed performance improvement, creating hydroxyl-rich surfaces in advance to enhance surface active sites and improve catalytic activity.

[0080] Please refer to Figure 4-1a , Figure 4-1b , Figure 4-1a This is a cyclic voltammetry curve collected by the AQT electrode in 1.0 M NaCl electrolyte. Figure 4-1b This is a cyclic voltammetry curve collected by the NA electrode in 1.0 M NaCl electrolyte.

[0081] Depend on Figure 4-1a , Figure 4-1b It can be seen that as the scan rate increases (from 5 mV / s to 100 mV / s), the current density and peak potential difference also increase accordingly. This is because a higher scan rate means a faster electrochemical reaction, resulting in a larger current. The increase in peak potential difference is consistent with the increase in the irreversibility of the reaction. In the region with a potential close to 0 V, the change in current density is small, indicating that in this potential range, the electrochemical system mainly exhibits capacitive behavior.

[0082] Please refer to Figure 4-2Linear scan voltammetry curves of AQT electrode and NA electrode.

[0083] Depend on Figure 4-2 It can be seen that the onset potential of AQT-Ti / RuO2-IrO2 at a scan rate of 10 mV / s is significantly lower than that of NA-RuO2-IrO2. This means that AQT-Ti / RuO2-IrO2 begins to undergo oxidation at a lower potential, and its current density is much higher than that of NA-RuO2-IrO2. This indicates that AQT-Ti / RuO2-IrO2 has higher electrochemical activity and better conductivity. In addition, the CV curve also shows a distinct and sharper oxidation peak at this potential, about 10 times that of NA-RuO2-IrO2, indicating a faster electron transfer rate. The oxidation peak of NA-RuO2-IrO2 is at a higher potential with a lower current density, indicating that the oxidation reaction of AQT-Ti / RuO2-IrO2 at this potential is more significant and kinetic. Comparing the oxidation onset potential and oxidation peak potential of the two electrode coatings, AQT-Ti / RuO2-IrO2 has a wider potential window, which is more advantageous in applications such as saline wastewater treatment and disinfection.

[0084] Please refer to Figure 4-3 Tafel slope curves for AQT and NA electrodes.

[0085] Depend on Figure 4-3 It can be seen that a smaller Tafel slope indicates a rapid increase in the CER rate and a decrease in the overpotential. The lower the Tafel slope value, the slower the overpotential growth rate. The Tafel slope of AQT-Ti / RuO2-IrO2 in the figure is 48.45 mV·dec. -1 The Tafel slope of NA-Ti / RuO2-IrO2 is 68.22 mV·dec. -1 The results show that AQT-Ti / RuO2-IrO2 has excellent CER activity and the fastest electron transfer rate, indicating that the AQT modification strategy is beneficial to improving interfacial CER kinetics.

[0086] Please refer to Figure 4-4 Electrochemical impedance spectroscopy of AQT electrode and NA electrode.

[0087] Depend on Figure 4-4It can be seen that the equivalent circuit obtained by batch fitting the IMPAC test data with Python best matches the impedance diagram. The data shows that Rct-AQT≈1 / 3Rct-NA, the exchange current density j0 is increased by about 3 times (j0∝1 / Rct), the charge transfer resistance is sharply reduced, the oxidation current (CV peak) at the same potential is significantly increased, and the Warburg coefficient σ in the EIS impedance spectrum of AQT-Ti / RuO2-IrO2 is 60% lower than that of NA-Ti / RuO2-IrO2. The equivalent diffusion layer thickness δ is also reduced proportionally (δ∝σ). This is mainly because the mud cracks on the surface of AQT-Ti / RuO2-IrO2 are more delicate and porous, the specific surface area is larger and more hydrophilic, and convection is easier to penetrate. After the interface charge transfer is accelerated, the interface concentration gradient decreases and the Nernst layer is thinned, so that the current in the low-frequency diffusion region is no longer "stifled". The overall limiting current can be increased by 30-40%.

[0088] Please refer to Figure 4-5 A bar chart comparing the surface hydroxylation density (Boehm titration) of AQT electrode and NA electrode.

[0089] Depend on Figure 4-5 It can be seen that Boehm titration further determined the surface hydroxylation density ρ-OH, and the surface hydroxylation density of AQT-RuO2-IrO2 was 2.46 × 10⁻⁶. 15 cm -2 The 3wt% H2O2 quenching-tempering treatment significantly improves the degree of hydroxylation on the electrode coating surface, and its relationship with the BET specific surface area ratio is relatively close to that of NA-Ti / RuO2-IrO2.

[0090] Please refer to Figure 4-6 A bar chart comparing the single-site transition frequency (TOF) of AQT and NA electrodes.

[0091] Depend on Figure 4-6 As can be seen from the conversion frequency calculation, the conversion frequency at a single site of the AQT-Ti / RuO2-IrO2 coating is 4.99 × 10⁻⁶. 2 s -1 ) is a NA-Ti / RuO2-IrO2 coating (2.17×10 2 s -1 The area is 2.30 times that of the surface electron transfer intrinsic activity, indicating that its surface electron transfer intrinsic activity is also higher (not just due to the increased area).

[0092] Please refer to Figure 4-7 A comparison of reaction kinetic curves of AQT electrode and NA electrode for treating low-concentration dyeing and printing wastewater.

[0093] Depend on Figure 4-7It can be seen that the second-order kinetic model (PSO) is more suitable for the degradation reaction of actual wastewater using the two different electrodes at 15 min. The degradation rate constant of the AQT-Ti / RuO2-IrO2 electrode is 1.092 min. -1 ) is NA-Ti / RuO2-IrO2 (0.536 min) -1 The difference between the increase in COD removal rate and the aforementioned rate constant is approximately 2.04 times that of the previous method. This difference is mainly because the IMPAC test data was obtained using a glassy carbon electrode supported on an etched coating powder, and the influence of the titanium substrate resistance was not considered. The COD removal rate mainly depends on the instantaneous concentration of organic matter in the solution, and the reaction process is controlled by active oxides or ·OH on the electrode surface. The AQT-Ti / RuO2-IrO2 electrode surface has a higher density of electrochemically active sites, which is conducive to the continuous generation of ·OH or high-valence metal oxides (M–O·). In addition, the AQT-Ti / RuO2-IrO2 has a lower polarization resistance, which reduces the energy barrier in the early stage of the reaction, resulting in a higher COD degradation rate.

[0094] In summary, the equivalent circuit fitting quantitatively demonstrates that the AQT-Ti / RuO2-IrO2 electrode simultaneously enhances the "charge transfer-diffusion" dual process, reducing Rct by 69% and increasing the active area by 78%. This directly translates into lower energy consumption, higher current efficiency, and a wider process window in water treatment, providing key electrochemical evidence for subsequent scale-up experiments and system-level life cycle assessments.

[0095] Please refer to Figure 5-1 Comparison of the degradation effects of electrodes treated with different quenching media on dyeing and printing wastewater.

[0096] Depend on Figure 5-1 It can be seen that during the degradation process of up to 60 minutes, the electrode quenched with hydrogen peroxide exhibited significantly better catalytic performance, with its degradation rate curve consistently remaining at the highest and continuously rising, far superior to other treatment methods.

[0097] Please refer to Figure 5-2 Figure 1 shows the relationship between COD removal rate and time in the electrocatalytic oxidation degradation of dyeing and printing wastewater using AQT and NA electrodes.

[0098] Depend on Figure 5-2It can be seen from the degradation performance of the wastewater treatment system that the degradation efficiencies of AQT-Ti / RuO2-IrO2 and NA-Ti / RuO2-IrO2 after 60 minutes of treatment were 77% and 55%, respectively. However, AQT-Ti / RuO2-IrO2 achieved a degradation efficiency of 63% and a COD concentration of 48.39 mg / L after only 10 minutes, while NA-Ti / RuO2-IrO2 only achieved 39% and a COD concentration of 67.53 mg / L. Even after 60 minutes of treatment, the COD concentration remained relatively low. The OD concentration was also slightly higher than that of AQT-Ti / RuO2-IrO2 at 50.15 mg / L within 10 minutes. AQT-Ti / RuO2-IrO2 not only significantly improved the catalytic electrochemical oxidation efficiency but also met the Chinese national standard for recycled water (FZ / T01107-2025, ≤50 mg / L) within 10 minutes, demonstrating excellent degradation efficiency. To comprehensively consider the stability of the effect, water quality safety, and cost balance, a treatment time of 10 minutes was selected for all subsequent applications. The observed performance improvement is fundamentally due to the fact that methods such as H2O2 quenching greatly optimize the number and state of surface hydroxyl groups, which serve as reaction centers.

[0099] Please refer to Figure 5-3 A comparison of energy consumption when AQT electrode and NA electrode are used to treat dyeing and printing wastewater.

[0100] Depend on Figure 5-3 It can be seen that although the instantaneous current efficiency and energy consumption of the two anodes are similar, after 10 minutes, the energy consumption per ton of water treated and the energy consumption per unit of COD removal of the surface hydroxylation-treated anode are higher than those of NA-Ti / RuO2-IrO2. This is because the COD removal rate of the surface hydroxylation-treated anode reaches 65% at around 10 minutes. This is attributed to the high concentration of organic matter near the electrode in the early stage, the optimization of the physical structure by H2O2 quenching impact, and the creation of surface hydroxylation to achieve simultaneous enhancement of electrode performance through the dual links of "charge transfer-diffusion". The electrocatalytic oxidation decreases after more than 10 minutes.

[0101] Analysis of the relationship between degradation performance and energy consumption in wastewater treatment systems shows that, with the goal of reusing effluent from electrocatalytic oxidation deep treatment, further analysis of treatment energy consumption reveals that the energy consumption per ton of water treated by the AQT-Ti / RuO2-IrO2 electrode is EC11.95 kWh·m³. -3 It is lower than other similar systems (15~25 kWh·m³). -3 The energy consumption per unit COD removal is 0.145 kWh / g-COD, which is also lower than other similar systems (0.17~0.20 kWh / g-COD). After 60 minutes of treatment with the NA-Ti / RuO2-IrO2 electrode, the energy consumption per ton of water is 69.10 kWh·m³. -3The energy consumption for COD removal is 1.494 kWh / g-COD, which is much higher than the energy consumption of AQT-Ti / RuO2-IrO2 electrode treatment.

[0102] Please refer to Figure 5-4 A comparison of the time-varying chloride ion consumption and chlorate ion generation between the AQT electrode and the NA electrode.

[0103] Depend on Figure 5-4 It can be seen that the continuous generation of chlorate ions and consumption of chloride ions in the wastewater solution eliminates the possibility of anode surface passivation. Furthermore, the chlorate ion production shows that it is almost zero before 10 minutes, but significantly increases after 10 minutes. Chlorate has physiological toxicity, and as a byproduct of water treatment, its accumulation in water bodies to a certain concentration (0.7 mg / L) can have significant toxic effects on organisms, posing a risk to water quality safety. This further demonstrates the significant advantages of the AQT-Ti / RuO2-IrO2 electrode in wastewater treatment.

[0104] Please refer to Figure 5-5 A comparison of the average current efficiency of electrocatalytic oxidation between AQT and NA electrodes.

[0105] Depend on Figure 5-5 Further calculations show that the average current efficiency (ACE) of the electrocatalytic oxidation of AQT-Ti / RuO2-IrO2 is 13.31%, and that of NA-Ti / RuO2-IrO2 is 7.1%, both at an excellent level (10%~20%) compared to similar systems. This demonstrates strong potential for practical engineering applications.

[0106] Please refer to Figure 5-6 The graph shows the performance changes of a reactor using AQT electrodes to treat actual dyeing and printing wastewater.

[0107] Depend on Figure 5-6 As can be seen, an extended semi-continuous flow reactor was constructed for treating low-concentration dyeing and finishing wastewater. Due to the highly stable catalytic activity of AQT-Ti / RuO2-IrO2, after 100 hours of continuous operation under fluctuating influent, the average degradation efficiency of AQT-Ti / RuO2-IrO2 was 61.48% within 10 minutes, with an average effluent COD concentration of 42.83 mg / L, consistently below 50 mg / L. The final effluent met the Chinese textile dyeing and finishing industry reuse water standard (FZ / T 01107-2025). This confirms the applicability of AQT-Ti / RuO2-IrO2 as a catalytic electrode and its practical application value in wastewater treatment.

[0108] The core mechanism of this invention lies in the fact that H2O2 thermal shock quenching reconstructs the microenvironment of the electrode surface through multiple synergistic effects. Rapid cooling induces the formation of an amorphous / nanocrystalline composite phase on the metal oxide surface, accompanied by characteristic mud crack morphology, significantly increasing the electrochemically active surface area and optimizing mass transfer channels. More importantly, this process constructs a hydroxylated interface (M–OH) in situ on the electrode surface, with the following multiple functional mechanisms: electronic structure and interface hydrophilicity regulation; surface hydroxyl groups act as strong electron-donating ligands, optimizing the d-band electronic state of the metal center and reducing the adsorption energy barrier of key intermediates; simultaneously, the hydroxyl-rich interface significantly improves the hydrophilicity of the electrode / solution interface, promoting the directional adsorption and dissociation of water molecules within the electric double layer and accelerating proton-coupled electron transfer kinetics; the directional generation and transformation of reactive oxygen species; in the electrocatalytic chlorination reaction, the pre-placed surface hydroxylated M–OH species play a dual role. On the one hand, they act as a direct precursor for the oxidation of water to generate hydroxyl radicals (•OH); on the other hand, they act as a precursor for chloride ions (Cl... - Nucleophilic attack on these surface M–OH sites removes water molecules through proton-hydroxyl recombination, driving the metal center to transform into a higher valence state (hydroxy) oxide. This indirect oxidation pathway effectively circumvents the high energy barrier of traditional water oxidation, achieving efficient and selective generation of •OH, thereby suppressing the competitive oxygen evolution reaction (OER) and improving the selectivity and reaction rate of the chlorine evolution reaction (CER). A balance between structural stability and conductivity is achieved through tempering, which eliminates quenching stress through controlled crystallization, repairs lattice defects, and rebuilds the long-range electronic conduction network while maintaining a high active surface area, ensuring the mechanical stability and conductivity of the electrode.

[0109] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A thermal shock-induced catalytic electrode, characterized in that, The catalytic electrode includes: Titanium metal substrate; And a mixed metal oxide catalyst layer formed on the surface of the titanium metal substrate; The mixed metal oxide catalyst layer has a hydroxylated surface, high specific surface area and large pore volume, and its microstructure is a uniform mud-crack-like porous structure containing nanoscale grains. The hydroxyl density on the surface of the mixed metal oxide catalyst layer is greater than 2.40 × 10⁻⁶. 15 pcs / cm²; The specific surface area of ​​the mixed metal oxide catalyst layer is greater than 26.00 m² / g; The total pore volume of the mixed metal oxide catalyst layer surface is greater than 0.08 cm³ / g, and the pore size ranges from ~95.46 to 98.77 nm. The measurement conditions are relative pressure P / Po = 0.

98.

2. The thermal shock-induced catalytic electrode as described in claim 1, characterized in that, The metal element in the mixed metal oxide catalyst layer is selected from two or more of ruthenium, iridium, cobalt, tin, tantalum, platinum, zinc, tungsten, strontium, titanium, niobium, molybdenum, cerium, rhodium, and palladium; the size of the nanoscale grains is 8-20 nm.

3. The method for preparing the thermal shock-induced catalytic electrode according to any one of claims 1-2, characterized in that, Includes the following steps: Step S1: Perform laser shock peening treatment on the surface of the titanium metal substrate to form a titanium metal substrate with a mesoscale array structure; Step S2: Using the dip-pull-space slope flow method, a mixed metal oxide solid solution precursor is loaded onto the titanium metal substrate to obtain a titanium-based mixed metal oxide electrode; Step S3: Anneal the titanium-based mixed metal oxide electrode; Step S4: Remove the annealed electrode at a certain temperature and quickly immerse it in a quenching medium for thermal shock quenching. Step S5: Perform low-temperature tempering on the quenched electrode and cool it to room temperature in the furnace to obtain the catalytic electrode.

4. The preparation method according to claim 3, characterized in that, Step S1 specifically includes the following steps: Pre-treat the surface of the titanium metal substrate; An energy-absorbing layer is coated onto the pretreated surface; A constraint layer is covered on the energy absorption layer; Using a short-pulse laser beam, laser shock peening treatment is performed on the surface of a titanium metal substrate covered with the energy absorption layer and the constraint layer through array scanning or beam shaping. Simultaneously, a residual compressive stress layer and a regularly arranged microstructure array are formed on the surface, namely the mesoscale array substrate. Remove the residual absorber and constraint layers to complete the preparation.

5. The preparation method according to claim 4, characterized in that, In step S1, the parameters for laser shock peening are: laser ring spacing 0.2-0.8mm, line spacing 0.03-0.1mm, and processing frequency not less than 80kHz.

6. The preparation method according to claim 3, characterized in that, In step S3, the annealing conditions are: holding at 500-550℃ for 1 hour, with a heating rate of 5-10℃ / minute.

7. The preparation method according to claim 3, characterized in that, In step S4, the quenching medium is a hydrogen peroxide aqueous solution with a concentration of 1-8 wt%.

8. The preparation method according to claim 3, characterized in that, In step S4, the quenching temperature is 405-465℃.

9. The preparation method according to claim 3, characterized in that, In step S5, the tempering conditions are: holding at 280-350℃ for 1 hour.

10. An application of the thermal shock induced catalytic electrode as described in any one of claims 1-2 in wastewater treatment or green disinfection scenarios.

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