Heterojunction NiO catalyst for efficient decomposition of ozone and preparation method thereof

Abstract

The invention aims to provide a heterojunction NiO catalyst for efficient decomposition of ozone and a preparation method thereof, and relates to the technical field of environmental catalyst.The preparation process of the catalyst adopts a coprecipitation method and comprises the steps that firstly, under the alkaline condition, a nickel nitrate solution is titrated at the constant titration speed, reaction temperature and stirring speed; after titration is completed, aging an obtained product, then carrying out suction filtration by using ethanol until a wet cake shape is formed, and transferring the wet cake-shaped material into a drying oven for drying treatment; the preparation method comprises the following steps: drying the raw materials, screening out 40-60-mesh particles through a sieve, and roasting the particles in a muffle furnace to finally obtain a black solid-phase catalyst; the catalyst shows excellent performance in the aspect of catalyzing ozonolysis under a high-humidity condition, and can keep stable and efficient catalytic activity even under various harsh operation conditions. Due to the excellent catalytic performance and stability, the catalyst can meet the requirement for stable catalysis of ozone in different environments.

Description

Technical Field

[0001] The present invention relates to the technical field of environmental catalysis, and particularly relates to a heterojunction NiO catalyst for efficient ozone decomposition and a preparation method thereof. Background Art

[0002] If a human body is in a high-concentration ozone environment for a long time, it may cause respiratory and cardio-pulmonary system diseases. In addition, high-concentration ozone has significant hazards to crops (yield reduction) and ecosystems (oxidative stress). With the process of industrialization and urbanization, the problem of near-surface ozone pollution has attracted increasing attention and has become one of the focuses of global air governance.

[0003] Currently, the methods for ozone decomposition mainly include thermal decomposition method, ultraviolet decomposition method, adsorption method, and catalytic decomposition method. The catalytic decomposition method has become the current mainstream technology due to its advantages such as low energy consumption, high efficiency, and wide applicability. Traditional ozone decomposition catalysts include noble metal catalysts (such as platinum, palladium, etc.) and transition metal oxide catalysts (such as manganese dioxide, copper oxide, etc.). Although noble metal catalysts have high activity, they are expensive and scarce in resources, making it difficult to be applied on a large scale; transition metal oxide catalysts have lower costs. For example, Mn-based metal catalysts are currently studied more and have better ozone decomposition performance, but they still have problems such as active sites being easily occupied by oxygen intermediates and water molecules during the reaction process under high humidity. As a result, their catalytic activity and stability decrease in some harsh environments, such as high-humidity environments, and cannot meet the actual requirements.

[0004] The patent with the publication number CN116265101B discloses a preparation process of a nitrogen-doped manganese dioxide-based ozone catalyst and its product, and optimizes the catalytic performance by regulating the loading ratio of the bimetallic active components of silver (Ag) and palladium (Pd) on the surface of the carrier. The prepared catalyst shows significantly extended stability in the field of ozone treatment, but its synthesis process has problems such as cumbersome procedures and cost-benefit issues caused by a large amount of noble metals used, which provides a clear technical breakthrough direction for subsequent process improvement. At the same time, the patent with the publication number CN116920876A discloses a novel ozone decomposition catalyst, and its preparation process involves reagents such as polyvinyl alcohol, styrene-butadiene rubber, carboxymethyl cellulose, and polyethylene glycol that may cause secondary pollution, and also poses a clear exposure risk to the respiratory system of operators. The above technical defects lead to the dual challenges of environmental compliance review pressure and limited feasibility of scale-up production in the industrial scale-up application of this catalyst system.

[0005] Therefore, it is of great significance to develop an ozone decomposition catalyst that is simple to prepare, low in cost, can be mass-produced, and still maintains high activity and stability under complex working conditions. Summary of the Invention

[0006] In view of the deficiencies of the prior art, the present invention provides the following technical solutions:

[0007] A preparation method of a heterojunction NiO catalyst for efficient ozone decomposition and its preparation method, comprising the following steps:

[0008] S1: Take nickel nitrate hexahydrate and dissolve it in deionized water to obtain a 0.8 - 1.2 mol / L salt solution A. Take sodium carbonate and sodium hydroxide, and dissolve them in deionized water according to a ratio of 2:1 - 4:1 to obtain solution B. Take sodium hydroxide and dissolve it in deionized water to obtain a 2 - 3 mol / L buffer solution C;

[0009] S2: Place solution A, solution B, and solution C in a room temperature ultrasonic cleaner for dissolution;

[0010] S3: Slowly drip solution A and solution B into the reaction vessel at a constant speed. Solution C acts as a buffer solution to control the pH value. During the titration process, the reaction temperature and the stirring rate remain constant;

[0011] S4: After the titration is completed, age for 5 hours. Then, perform suction filtration on the obtained suspension, and use an ethanol solution (the concentration range of the ethanol solution is 0 - 100%) for suction filtration until the filtrate is neutral to obtain a wet filter cake;

[0012] S5: Transfer the wet filter cake to an oven for drying, and obtain the catalyst precursor after crushing and sieving;

[0013] S6: Perform calcination treatment on the precursor to obtain the final nickel oxide catalyst.

[0014] Further, the dissolution time in S2 is about 15 minutes.

[0015] Further, 100 - 150 mL of deionized water should be prepared in advance in the reaction vessel in S3. During the titration process, solutions A and B are dripped at the same speed, which is 1 - 2 ml / min. The pH range controlled by solution C should be 10 - 10.5. The reaction temperature during the titration process is 60 - 80°C, and the stirring speed of the stirrer is maintained at 200 - 250 rpm.

[0016] Further, the aging temperature and stirring rate in S4 should be consistent with the titration process.

[0017] Further, the drying temperature in S5 is 70 - 80°C, the duration is controlled within 24 hours, and the sieve size is 40 - 60 mesh;

[0018] Further, the calcination temperature in S6 is 200°C - 400°C, and the duration is 4 - 12 hours.

[0019] Compared with the prior art, the technical solution of the present application has the following beneficial effects:

[0020] The present invention uses nickel nitrate hexahydrate (Ni(NO 3 )) 2 ·6H 2 O) as the nickel source, releases Ni 2+ through an aqueous solution, and provides a metal active center for the formation of nickel oxide; NaOH can provide a strong alkaline environment to promote the rapid hydrolysis of Ni 2+ to generate Ni(OH) 2 colloid; while Na(CO) 3 introduces CO 3 2- to slowly release alkalinity, delays the precipitation rate by forming a NiCO 3 intermediate, and improves the grain homogeneity; by online monitoring the pH and adjusting the dropping rate of solution C, the reaction system is stabilized in the pH range of 10.0 - 10.5. Under this condition, Ni 2+ exists in the form of [Ni(OH) 4 2- complex, which is beneficial to the formation of a highly dispersed precursor; continuously stir and age at 70 °C for 5 hours to promote the phase transformation of Ni(OH) 2 to the thermodynamically more stable β-Ni(OH) 2 phase, laying a foundation for the subsequent calcination to generate heterojunction NiO. The low surface tension property of ethanol (24 mN / m) replaces water molecules, reduces the capillary force, prevents the collapse of pores during the drying process, and retains the mesoporous structure. During the calcination process, the residual carbon species washed by ethanol are partially carbonized during the calcination to form surface defect sites, enhancing the electron transfer ability. Through the synergistic regulation of co-precipitation - calcination, the NiO catalyst realizes the optimized integration of mesoporous lattice defects, enabling it to maintain high-efficiency adsorption and decomposition activity of ozone molecules even in a high-humidity (RH = 90%) environment. Brief Description of the Drawings

[0021] Figure 1 is the catalyst preparation flow chart of the present invention;

[0022] Figure 2 is the ozone conversion effect comparison chart of the catalysts prepared under different suction filtration conditions of the present invention in an environment with a relative humidity of 90%;

[0023] Figure 3 is the XRD pattern of the catalysts prepared under different suction filtration conditions of the present invention;

[0024] Figure 4 is the SEM image of the catalyst of the present invention;

[0025] Figure 5 is the in-situ infrared image of the catalyst of the present invention. Detailed Embodiments

[0026] ​The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the protection scope of the present invention.

[0027] Embodiment 1:

[0028] In this embodiment, a method for preparing a catalyst capable of catalyzing ozone decomposition in a high-humidity environment is disclosed in detail. This method involves performing suction filtration with a suction filtration reagent having an ethanol solution concentration of 100%, and calcining at 300 °C to finally prepare a nickel oxide ozone catalyst (NiO-E-300 °C). The specific steps are as follows:

[0029] S1: Weigh 0.05 mol of nickel nitrate hexahydrate and slowly add it to a high-borosilicate glass beaker containing 50 mL of deionized water to obtain a 1 mol / L salt solution A. Subsequently, weigh 0.8 mol of sodium hydroxide and 0.025 mol of sodium carbonate with the same balance and add them to 50 mL of deionized water in sequence to obtain an alkali solution B. Finally, weigh 4 grams of sodium hydroxide and add 25 mL of deionized water to obtain an alkali solution C.

[0030] S2: Then, put solution A, solution B, and solution C together into an ultrasonic cleaner with a power of 250 W and perform ultrasonic treatment at room temperature of 25 °C for 15 min to ensure that the solutes are fully dispersed.

[0031] S3: After complete dissolution, transfer it to a burette. Pre-add 150 mL of deionized water to a glass reaction vessel, precisely control the temperature inside the reaction vessel at 70 °C through a constant-temperature water bath device, turn on a variable-frequency stirrer, set the stirring rate to 200 rpm, and use the double-drop method to uniformly drip solution A and solution B into the reaction kettle at the same rate of 1 mL / min. During the titration process, use a pH meter to precisely control the dripping of solution C according to the real-time pH value of the reaction solution, so that the pH value of the reaction system is always stable between 10 and 10.5.

[0032] S4: After the titration is completed, continue to age the reaction solution under stirring conditions of 70 °C and 200 rpm for 5 hours. Then, perform a suction filtration operation on the obtained suspension through a vacuum suction filtration device, select anhydrous ethanol for suction filtration and washing, and perform suction filtration 3 times repeatedly until the filtrate is neutral to obtain a wet filter cake.

[0033] S5: Transfer the wet filter cake to a programmable oven, set the temperature to 70 °C, and the drying time to 24 hours. After the dried filter cake is crushed, sieve it through 40-mesh and 60-mesh standard sieve meshes in sequence to remove too large and too small particles to obtain a catalyst precursor with a uniform particle size.

[0034] S6: placing the precursor into a high temperature muffle furnace, heating the temperature from room temperature to 300°C at a heating rate of 1.6°C / min, and calcining at 300°C for 4 hours to obtain a black catalyst NiO-E-300°C.

[0035] from Figure 3 It can be concluded from the XRD spectrum of the nickel oxide catalyst shown that the catalyst presents a standard nickel oxide structure; however, due to the presence of many defects, its crystallinity is poor. The SEM morphology of the nickel oxide catalyst is as follows: Figure 3 As shown, it indicates that it forms a flower-like structure, which is beneficial to expose more active sites and improve the catalytic performance;

[0036] In this example, an experimental study on the catalytic decomposition of ozone in a high humidity environment was conducted on a nickel oxide catalyst (NiO-E-300°C) prepared by filtration of ethanol and calcination at 300°C:

[0037] Accurately weigh 0.05g of catalyst and place it in a quartz reaction tube with an inner diameter of 4mm, and install the reaction tube in a precise temperature control device. During the experiment, the gas flow rate was set to 700ml / min, the mass space velocity was 840L / (g·h), the ozone inlet concentration was maintained at 100ppm, and the relative humidity was constant at 90%. The ozone removal efficiency curve obtained in the experiment is shown in Figure 2 As shown; through Figure 2 In-depth analysis of the data shows that under harsh conditions of relative humidity as high as 90%, the NiO-E-300℃ catalyst can achieve complete decomposition of ozone.

[0038] Embodiment 2:

[0039] This embodiment discloses in detail a nickel oxide catalyst (NiO-H+E-300°C) calcined at 300°C by alternately filtering with a filtration agent having an ethanol concentration of 0% and an ethanol concentration of 100%. The specific steps are as follows:

[0040] S1: In an experimental environment that meets the clean standard, use an electronic analytical balance with an accuracy of up to 0.0001g to weigh 0.05mol of nickel nitrate hexahydrate, and slowly add it to a borosilicate glass beaker filled with 50mL of deionized water to obtain a 1mol / L salt solution A. Subsequently, use the same balance to weigh 0.8mol of sodium hydroxide and 0.025mol of sodium carbonate, and add them to 50mL of deionized water in sequence to obtain an alkaline solution B. Finally, weigh 4g of sodium hydroxide and add 25mL of deionized water to obtain an alkaline solution C.

[0041] S2: Subsequently, put solution A, solution B and solution C together into an ultrasonic cleaner with a power of 250 W, and perform ultrasonic treatment at room temperature of 25 °C for 15 min to ensure that the solutes are fully dispersed;

[0042] S3: After complete dissolution, transfer it to a burette. Pre-add 150 mL of deionized water to the glass reaction vessel. Precise control the temperature inside the reaction vessel at 70 °C through a constant temperature water bath device. Turn on the variable frequency stirrer, set the stirring rate to 200 rpm, and use the double-drop method to uniformly drip solution A and solution B into the reaction kettle at the same rate of 1 mL / min; during the titration process, use a pH meter to precisely control the dripping of solution C according to the real-time pH value of the reaction solution, so that the pH value of the reaction system is always stable between 10 and 10.5;

[0043] S4: After the titration is completed, continue to age the reaction solution for 5 hours under the conditions of stirring at 70 °C and 200 rpm; after the aging is completed, use a vacuum filtration device to perform filtration operation on the obtained suspension. Select anhydrous ethanol and deionized water as detergents for filtration washing, and filter and wash repeatedly 3 times in sequence, first with deionized water and then with anhydrous ethanol, until the filtrate is neutral, thereby obtaining a wet filter cake;

[0044] S5: Transfer the wet filter cake to a programmable oven, set the temperature to 70 °C, and the drying time to 24 hours. After the dried filter cake is crushed, sieve it through 40-mesh and 60-mesh standard sieve meshes in sequence to remove too large and too small particles, and obtain a catalyst precursor with a uniform particle size;

[0045] S6: Put the precursor into a high-temperature muffle furnace, heat it from room temperature to 300 °C at a heating rate of 1.6 °C / min, and calcine it at 300 °C for 4 hours to obtain a black nickel oxide ozone catalyst NiO-H+E-300 °C;

[0046] In addition, in this example, for the nickel oxide catalyst (NiO-H+E-300 °C) prepared by filtration with ethanol and deionized water and then calcined at 300 °C, an experimental study on ozone catalytic decomposition in a high-humidity environment was carried out:

[0047] Accurately weigh 0.05 g of the catalyst, place it in a quartz reaction tube with an inner diameter of 4 mm, and install this quartz reaction tube in a device with precise temperature control ability; during the experiment, set the gas flow rate to 700 ml / min, the mass space velocity to 840 L / (g·h), the ozone inlet concentration to be stably maintained at 100 ppm, and the relative humidity to be constantly controlled at 90%; the ozone removal efficiency curve obtained from the experiment is as Figure 2 shown; by Figure 2Analysis of the data in [reference] shows that under the harsh experimental conditions with a relative humidity as high as 90%, the removal efficiency of ozone by the NiO-H+E-300℃ catalyst can also reach 100%.

[0048] Example 3:

[0049] This example systematically introduces the preparation method and performance evaluation of a nickel oxide ozone decomposition catalyst (NiO-H-300℃) using a filtration reagent with an ethanol concentration of 0% and calcined at 300℃. The specific implementation process is as follows:

[0050] S1: In a clean standard experimental environment, use an electronic analytical balance with an accuracy of up to 0.0001 g to weigh 0.05 mol of nickel nitrate hexahydrate, and slowly add it to a high-borosilicate glass beaker containing 50 mL of deionized water to obtain a 1 mol / L salt solution A. Subsequently, use the same balance to weigh 0.8 mol of sodium hydroxide and 0.025 mol of sodium carbonate, and add them to 50 mL of deionized water in sequence to obtain an alkali solution B. Finally, weigh 4 g of sodium hydroxide and add 25 mL of deionized water to obtain an alkali solution C;

[0051] S2: Then, put solution A, solution B, and solution C into an ultrasonic cleaner with a power of 250 W and perform cavitation treatment at room temperature of 25℃ for 15 min to ensure that the solutes are fully dispersed;

[0052] S3: After complete dissolution, transfer it to a burette. Pre-add 150 mL of deionized water to the glass reaction vessel, precisely control the temperature inside the reaction vessel at 70℃ through a constant temperature water bath device, turn on the variable frequency stirrer, set the stirring rate to 200 rpm, and use the double-drop method to uniformly drip solution A and solution B into the reaction kettle at the same rate of 1 mL / min; during the titration process, use a pH meter to precisely control the addition of solution C according to the real-time pH value of the reaction solution to keep the pH value of the reaction system stable between 10 and 10.5;

[0053] S4: After the titration, continue to age the reaction solution for 5 hours under stirring conditions of 70℃ and 200 rpm; after the aging is completed, use a vacuum filtration device to perform a filtration operation on the obtained suspension, select deionized water as the filtration reagent and cycle the filtration 3 times until the filtrate is neutral, thereby obtaining a wet filter cake;

[0054] S5: Transfer the wet filter cake to a programmable oven, set the temperature to 70℃, and the drying time to 24 hours. After the dried filter cake is crushed, sieve it through 40-mesh and 60-mesh standard sieves in sequence to remove too large and too small particles, and obtain a catalyst precursor with a uniform particle size;

[0055] S6: Place the precursor in a high-temperature muffle furnace and heat it from room temperature to 300 °C at a heating rate of 1.6 °C / min, and then calcine it at 300 °C for 4 hours to obtain the black nickel oxide ozone catalyst NiO-H-300 °C;

[0056] In addition, in this example, for the nickel oxide catalyst (NiO-H-300 °C), an experimental study on ozone catalytic decomposition in a high-humidity environment was carried out:

[0057] Accurately weigh 0.05 g of the catalyst, place it in a quartz reaction tube with an inner diameter of 4 mm, and install this quartz reaction tube in a device with precise temperature control ability; during the experiment, set the gas flow rate to 700 ml / min, the mass space velocity to 840 L / (g·h), the ozone inlet concentration to be stably maintained at 100 ppm, and the relative humidity to be constantly controlled at 90%; the ozone removal efficiency curve obtained from the experiment is as Figure 2 shown; by analyzing the data in Figure 2 , it can be seen that under the harsh experimental conditions with a relative humidity as high as 90%, NiO-H-300 °C maintains an 80% ozone conversion efficiency.

[0058] Example 4:

[0059] This example details the nickel oxide catalyst (NiO-E-400 °C) obtained by suction filtration with a suction filtration reagent with an ethanol concentration of 100% and calcined at 400 °C. The specific implementation process is as follows:

[0060] S1: In an experimental environment meeting the cleanliness standard, use an electronic analytical balance with an accuracy of up to 0.0001 g to weigh 0.05 mol of nickel nitrate hexahydrate, and slowly add it to a high-borosilicate glass beaker containing 50 mL of deionized water to obtain a 1 mol / L salt solution A. Subsequently, use the same balance to weigh 0.8 mol of sodium hydroxide and 0.025 mol of sodium carbonate, and add them to 50 mL of deionized water in sequence to obtain an alkali solution B. Finally, weigh 4 g of sodium hydroxide and add 25 mL of deionized water to obtain an alkali solution C;

[0061] S2: Then put solution A, solution B, and solution C into an ultrasonic cleaner with a power of 250 W and perform cavitation treatment at room temperature of 25 °C for 15 min to ensure that the solutes are fully dispersed;

[0062] S3: After complete dissolution, transfer it to a burette. Pre-add 150 mL of deionized water to the glass reaction vessel. Accurately control the temperature inside the reaction vessel at 70 °C through a constant temperature water bath device. Turn on the variable frequency stirrer, set the stirring rate to 200 rpm, and adopt the double-drop method. At the same rate of 1 mL / min, uniformly drip solution A and solution B into the reaction kettle; during the titration process, use a pH meter to accurately control the dripping of solution C according to the real-time pH value of the reaction solution, so that the pH value of the reaction system is always stable between 10 and 10.5;

[0063] S4: After the titration is completed, continue to age the reaction solution for 5 hours under the conditions of stirring at 70 °C and 200 rpm; after the aging is completed, use a vacuum filtration device to perform a filtration operation on the obtained suspension. Select a filtration reagent with an ethanol concentration of 100%, and filter it 3 times in a cycle until the filtrate is neutral, thereby obtaining a wet filter cake;

[0064] S5: Transfer the wet filter cake to a programmable oven, set the temperature to 70 °C, and the drying time to 24 hours. After the dried filter cake is crushed, sieve it through 40-mesh and 60-mesh standard sieve meshes in sequence to remove too large and too small particles, and obtain a catalyst precursor with a uniform particle size;

[0065] S6: Put the precursor into a high-temperature muffle furnace, raise the temperature from room temperature to 400 °C at a heating rate of 1.6 °C / min, and calcine it at 400 °C for 4 hours to obtain a black nickel oxide ozone catalyst NiO-E-400 °C;

[0066] In addition, in this example, for the nickel oxide catalyst (NiO-E-400 °C), an experimental study on ozone catalytic decomposition in a high-humidity environment was carried out:

[0067] Accurately weigh 0.05 g of the catalyst, place it in a quartz reaction tube with an inner diameter of 4 mm, and install this quartz reaction tube in a device with precise temperature control ability; during the experiment, set the gas flow rate to 700 ml / min, the mass space velocity to 840 L / (g·h), the ozone inlet concentration to be stably maintained at 100 ppm, and the relative humidity to be constantly controlled at 90%; the ozone removal efficiency curve obtained from the experiment is as Figure 2 shown; through the analysis of the data in Figure 2 , it can be seen that under the harsh experimental conditions with a relative humidity as high as 90%, NiO-E-400 °C maintains a 60% steady-state ozone conversion rate.

[0068] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification to better explain the principles and practical applications of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A method for preparing a heterojunction NiO catalyst, characterized in that: The following steps are involved: S1: nickel nitrate hexahydrate is dissolved in deionized water to prepare a 0.8-1.2 mol / L salt solution A, sodium carbonate and sodium hydroxide are dissolved in deionized water in a ratio of 2:1-4:1 to prepare solution B, and sodium hydroxide is dissolved in deionized water to prepare a 2-3 mol / L buffer solution C; S2: Solution A, solution B and solution C are placed in an ultrasonic cleaning machine at room temperature to dissolve; S3: Solution A and solution B are uniformly dripped into the reaction container, and solution C acts as a buffer solution to adjust the pH value. During the titration process, the reaction temperature and stirring rate remain constant; S4: After the titration is completed, the suspension is aged for 5 hours, and then the obtained suspension is filtered using an ethanol solution until the filtrate is neutral to obtain a wet filter cake; S5: transferring the wet filter cake to an oven for drying, and crushing and sieving to obtain a catalyst precursor; S6: calcining the precursor to obtain a nickel oxide catalyst.

2. The method for preparing a heterojunction NiO catalyst according to claim 1, characterized in that: The dissolution time in S2 is 15 minutes.

3. The method for preparing a heterojunction NiO catalyst according to claim 1, characterized in that: In the reaction container of S3, 100-150 mL of deionized water is prepared in advance. During the titration, solution A and solution B are kept at the same speed of 1-2 ml / min. The pH range of solution C is regulated to be 10-10.

5. During the titration, the reaction temperature is 60-80° C., and the agitator speed is maintained at 200-250 rpm.

4. The method for preparing a heterojunction NiO catalyst according to claim 1, characterized in that: The aging temperature and stirring rate in S4 are consistent with the titration process; the concentration range of the ethanol solution is 0-100%.

5. The method for preparing a heterojunction NiO catalyst according to claim 1, characterized in that: In the step S5, the drying temperature is 70-80° C., the drying time is controlled at 24 h, and the sieving size is 40-60 mesh.

6. The method for preparing a heterojunction NiO catalyst according to claim 1, characterized in that: The calcination temperature in S6 is 200° C. to 400° C., and the calcination time is 4 to 12 hours.

7. A heterojunction NiO catalyst prepared by the preparation method according to any one of claims 1 to 6.

8. Use of a heterojunction NiO catalyst according to claim 7 in highly efficient catalytic ozone decomposition under high humidity and high-speed airflow environments.

Images