阅读说明：本技术 氮掺杂介孔空心碳纳米球负载金属催化剂及其制备方法与应用 (Nitrogen-doped mesoporous hollow carbon nanosphere loaded metal catalyst and preparation method and application thereof ) 是由 贾海园 尤伟 李亚萍 宋龙森 于 2021-10-25 设计创作，主要内容包括：本发明公开了一种氮掺杂介孔空心碳纳米球负载金属催化剂及其制备方法与应用,在溶剂体系中,以二氧化硅微球为模板剂,以间苯二酚-甲醛共聚物为碳源,通过沉积沉淀法制备固体实心微球,将固体实心微球经过热处理和刻蚀制得介孔空心碳纳米球；将活性金属源浸渍附着于介孔空心碳纳米球表面,以氨气为氮源,经过热处理,制备得到氮掺杂介孔空心碳纳米球负载金属催化剂。制得氮掺杂介孔空心碳纳米球负载金属催化剂具有重要的实用价值。(The invention discloses a nitrogen-doped mesoporous hollow carbon nanosphere loaded metal catalyst as well as a preparation method and application thereof, wherein in a solvent system, silicon dioxide microspheres are used as a template agent, resorcinol-formaldehyde copolymer is used as a carbon source, solid microspheres are prepared by a deposition precipitation method, and the solid microspheres are subjected to heat treatment and etching to prepare mesoporous hollow carbon nanospheres; and (3) dipping and attaching an active metal source to the surface of the mesoporous hollow carbon nanospheres, and performing heat treatment by using ammonia gas as a nitrogen source to prepare the nitrogen-doped mesoporous hollow carbon nanosphere supported metal catalyst. The prepared nitrogen-doped mesoporous hollow carbon nanosphere supported metal catalyst has important practical value.)

1. A nitrogen-doped mesoporous hollow carbon nanosphere loaded metal catalyst is characterized in that: comprises nitrogen-doped mesoporous hollow carbon nanospheres and metal ions loaded on the nanospheres.

2. A preparation method of a nitrogen-doped mesoporous hollow carbon nanosphere supported metal catalyst is characterized by comprising the following steps: the method comprises the following steps:

in a solvent system, preparing solid microspheres by using a deposition precipitation method by using silicon dioxide microspheres as a template agent and resorcinol-formaldehyde copolymer as a carbon source, and performing heat treatment and etching on the solid microspheres to obtain mesoporous hollow carbon nanospheres;

and (3) dipping and attaching an active metal source to the surface of the mesoporous hollow carbon nanospheres, and performing heat treatment by using ammonia as a nitrogen source to prepare the nitrogen-doped mesoporous hollow carbon nanosphere supported metal catalyst.

3. The preparation method of the nitrogen-doped mesoporous hollow carbon nanosphere supported metal catalyst according to claim 2, characterized in that: the silicon dioxide microspheres are silicon dioxide microspheres synthesized in situ;

further, the particle size of the silicon dioxide microspheres is 200-500 nm;

further, the preparation method of the silicon dioxide microspheres comprises the following steps: adding tetrapropoxysilane and ethyl orthosilicate into the ethanol, water and ammonia water solution which are uniformly mixed, stirring, and reacting to prepare silicon dioxide microspheres;

further, ammonia water is used for adjusting the pH value of the reaction solution to 8-10;

furthermore, the reaction time of the tetrapropoxysilane and the tetraethoxysilane in the ethanol and ammonia water solution is 10-20 min;

further, tetrapropoxysilane and tetraethoxysilane react in a mixed solution of ethanol and ammonia water, after the silicon dioxide microspheres are synthesized in situ, resorcinol and formaldehyde solution are added, and the reaction is continued to prepare the solid microspheres coated with the carbon source oligomer.

4. The method for preparing the nitrogen-doped mesoporous hollow carbon nanosphere supported metal catalyst according to claim 3, wherein the method comprises the following steps: the method also comprises the steps of carrying out centrifugal washing and drying on the solid microspheres coated with the carbon source oligomer;

further, the centrifugal washing times are 3-10, and the solution obtained by centrifugal washing is aqueous solution and ethanol solution;

furthermore, the drying temperature is 50-80 ℃, and the drying time is 6-12 h.

5. The method for preparing the nitrogen-doped mesoporous hollow carbon nanosphere supported metal catalyst according to claim 3, wherein the method comprises the following steps: further comprises the following steps of carrying out a heat treatment process on the carbon source oligomer-coated solid microspheres: heat treatment is carried out for 3-6h at the temperature of 600-900 ℃ in the inert gas atmosphere.

6. The preparation method of the nitrogen-doped mesoporous hollow carbon nanosphere supported metal catalyst according to claim 2, characterized in that: the etching is carried out by adopting acid or alkali;

further, the acid is hydrofluoric acid, and the alkali is sodium hydroxide;

further, the etching time of acid or alkali is 12-48 h;

furthermore, the concentration of the hydrofluoric acid solution is 5-10 wt%; the concentration of the sodium hydroxide solution is 10-15 wt%;

in some embodiments, the method further comprises a step of freeze-drying the etched mesoporous hollow carbon nanospheres;

further, the freeze-drying time is 12-24 h.

7. The preparation method of the nitrogen-doped mesoporous hollow carbon nanosphere supported metal catalyst according to claim 2, characterized in that: the active metal source is soluble salt of Fe, Co or Ni;

further, the soluble salt is chloride, nitrate or acetate of Fe, Co or Ni;

further, the active metal source is dipped and attached to the mesoporous hollow carbon nanospheres by an isometric dipping method;

furthermore, the metal loading on the mesoporous hollow carbon nanospheres is 0.1-8%.

8. The preparation method of the nitrogen-doped mesoporous hollow carbon nanosphere supported metal catalyst according to claim 2, characterized in that: the preparation method also comprises the steps of freeze drying and heat treatment of the prepared mesoporous hollow carbon nanosphere loaded metal catalyst;

further, the freeze drying time is 12-24 h;

further, the heat treatment atmosphere is a mixed gas of inert gas and ammonia gas, and the volume ratio of the inert gas to the ammonia gas is 2-4: 1;

further, the temperature of the heat treatment is 600-900 ℃, and the time of the heat treatment is 1-4 h.

9. The nitrogen-doped mesoporous hollow carbon nanosphere supported metal catalyst prepared by the preparation method of any one of claims 2-8.

10. The use of the nitrogen-doped mesoporous hollow carbon nanosphere supported metal catalyst of claim 1 or 9 in electrocatalytic oxygen reduction; especially in the preparation of hydrogen peroxide by electrocatalytic oxygen reduction.

Technical Field

The invention belongs to the technical field of energy chemical industry, and particularly relates to a nitrogen-doped mesoporous hollow carbon nanosphere supported metal catalyst and a preparation method thereof.

Background

The statements herein merely provide background information related to the present disclosure and may not necessarily constitute prior art.

Hydrogen peroxide is an important environmentally friendly oxidationThe agent has the by-product of water during the use process, avoids the release of chlorine and the generation of high-concentration salt, and is widely used as a bleaching agent, a disinfectant, an organic matter degradation agent, a sewage treatment oxidant and the like in the industries of chemistry, chemical engineering, medical treatment and the like. At present, the production of hydrogen peroxide is dominated by the anthraquinone process developed a century ago. Although the anthraquinone process can produce a large amount of high-concentration hydrogen peroxide, the steps of hydrogenation, oxidation, extraction, separation, concentration and the like are required, the synthesis process is complex, the requirements on equipment are high, the pollution is high, the energy consumption is high, the obtained hydrogen peroxide needs to be concentrated to 70 wt% so as to reduce the transportation cost, the hydrogen peroxide is easy to decompose and explode at high concentration, the instability of the hydrogen peroxide brings fatal safety problems to transportation and storage, and the defects limit the wide application of the anthraquinone process and are mainly suitable for large-scale industrial production processes. Therefore, there is an increasing interest in developing low cost, distributed, and safe and efficient hydrogen peroxide production processes. H₂And O₂The direct synthesis is one of the alternative methods, the route is environment-friendly, simple and economical, but the selectivity and yield of the hydrogen peroxide are low, the explosive safety problem exists, and the catalyst is easy to decompose the hydrogen peroxide, so that the practical production application of the synthesis method is limited.

The electrocatalytic oxygen reduction method for producing hydrogen peroxide is a relatively new process. The method has low energy consumption and low investment, takes the regenerated electric power as energy, takes water and air as green precursors, realizes the synthesis of the hydrogen peroxide at normal temperature and normal pressure, can effectively put an end to the potential safety hazard existing in the anthraquinone method and the direct synthesis method, is suitable for small-scale in-situ production of the hydrogen peroxide, does not need transportation, and thus reduces the related cost.

The synthesis of hydrogen peroxide by electrocatalytic oxygen reduction is an environmentally friendly and safe and reliable synthesis method for which noble metals and their alloys (Pt and Pd) are relatively excellent catalysts, however, their wide application is limited by their rarity.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a nitrogen-doped mesoporous hollow carbon nanosphere supported metal catalyst and a preparation method and application thereof.

In order to achieve the purpose, the invention is realized by the following technical scheme:

in a first aspect, the invention provides a nitrogen-doped mesoporous hollow carbon nanosphere supported metal catalyst, which comprises nitrogen-doped mesoporous hollow carbon nanospheres and metal ions supported thereon.

In a second aspect, the invention provides a preparation method of a nitrogen-doped mesoporous hollow carbon nanosphere supported metal catalyst, which comprises the following steps:

in a solvent system, preparing solid microspheres by using a deposition precipitation method by using silicon dioxide microspheres as a template agent and resorcinol-formaldehyde copolymer as a carbon source, and performing heat treatment and etching on the solid microspheres to obtain mesoporous hollow carbon nanospheres;

and (3) dipping and attaching an active metal source to the surface of the mesoporous hollow carbon nanospheres, and performing heat treatment by using ammonia gas as a nitrogen source to prepare the nitrogen-doped mesoporous hollow carbon nanosphere supported metal catalyst.

In a third aspect, the invention provides the nitrogen-doped mesoporous hollow carbon nanosphere supported metal catalyst prepared by the preparation method.

In a fourth aspect, the invention provides an application of the nitrogen-doped mesoporous hollow carbon nanosphere loaded metal catalyst in electrocatalytic oxygen reduction; especially in the preparation of hydrogen peroxide by electrocatalytic oxygen reduction.

The above one or more embodiments of the present invention achieve the following advantageous effects:

compared with noble metals, transition metals and carbon materials are inexpensive and abundant, and are ideal catalysts for electrocatalytic oxygen reduction reactions. Therefore, the nitrogen-doped mesoporous hollow carbon nanosphere loaded transition metal catalyst prepared by taking the in-situ synthesized silica spheres as a template agent, the resorcinol-formaldehyde copolymer as a carbon source, the ammonia gas as a nitrogen source and the metal salt as an active metal source through a deposition precipitation method and then loading the active transition metal on the surface of the mesoporous hollow carbon nanosphere through an isovolumetric impregnation method has important practical value.

Compared with the common anthraquinone method and direct synthesis method, the reaction for producing hydrogen peroxide by electrocatalysis cathode oxygen reduction applied by the proposed catalyst has the advantages of environmental friendliness, difficult explosion, effective avoidance of long-distance transportation, direct application of in-situ synthesized dilute hydrogen peroxide in sewage treatment, sterilization and disinfection and the like.

The reaction of the electro-catalytic cathode oxygen reduction to produce hydrogen peroxide is carried out at normal temperature and normal pressure, the electrolyte is perchloric acid solution or phosphate solution, and the synthesized hydrogen peroxide can stably exist.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.

FIG. 1 is a HRTEM picture of a 4% Co-N-C catalyst prepared in example 3 of the present invention.

FIG. 2 is a nitrogen adsorption and desorption isotherm of mesoporous hollow carbon nanospheres as a carrier for the catalyst of the present invention.

FIG. 3 shows the results of activity (a), selectivity (b) and stability (C) of the 0.5% Co-N-C catalyst prepared in example 1 in the reaction test example for preparing hydrogen peroxide by electrocatalytic oxygen reduction.

FIG. 4 shows the results of activity (a) and selectivity (b) of comparative test examples in which 1% Co-N-C catalyst prepared in example 2 was used to prepare hydrogen peroxide by electrocatalytic oxygen reduction.

FIG. 5 shows the results of activity (a) and selectivity (b) of comparative test examples in which the 4% Co-N-C catalyst prepared in example 3 was used to prepare hydrogen peroxide by electrocatalytic oxygen reduction.

Detailed Description

It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

In a first aspect, the invention provides a nitrogen-doped mesoporous hollow carbon nanosphere supported metal catalyst, which comprises nitrogen-doped mesoporous hollow carbon nanospheres and metal ions supported thereon.

In a second aspect, the invention provides a preparation method of a nitrogen-doped mesoporous hollow carbon nanosphere supported metal catalyst, which comprises the following steps:

in a solvent system, taking silicon dioxide microspheres (with high cost performance, mild hydrolysis conditions and easy control of mesoporous size) as a template agent, taking resorcinol-formaldehyde copolymer as a carbon source, preparing solid microspheres by a deposition precipitation method, and performing heat treatment and etching on the solid microspheres to prepare mesoporous hollow carbon nanospheres;

the active metal source is dipped and attached to the surface of the mesoporous hollow carbon nanospheres, ammonia gas is used as a nitrogen source (ammonia gas is a common nitrogen doping mode), and the nitrogen-doped mesoporous hollow carbon nanosphere supported metal catalyst is prepared by heat treatment.

In some embodiments, the silica microspheres are in situ synthesized silica microspheres.

Further, the particle size of the silica microspheres is 200-500 nm.

Further, the preparation method of the silicon dioxide microspheres comprises the following steps: adding tetrapropoxysilane and ethyl orthosilicate into the uniformly mixed ethanol, water and ammonia water (alkaline condition for preparing proper silicon source hydrolysis), stirring, and reacting to obtain the silicon dioxide microspheres.

Further, the pH of the reaction solution is adjusted to 8 to 10 with ammonia water.

Furthermore, the reaction time of the tetrapropoxysilane and the tetraethoxysilane in the ethanol and ammonia water solution is 10-20 min.

Further, tetrapropoxysilane and tetraethoxysilane react in a mixed solution of ethanol and ammonia water, after the silicon dioxide microspheres are synthesized in situ, resorcinol and formaldehyde solution are added, and the reaction is continued to prepare the solid microspheres coated with the carbon source oligomer.

In some embodiments, the method further comprises the steps of centrifugally washing and drying the carbon source oligomer-coated solid microspheres.

Further, the centrifugal washing times are 3-10 times, and the solution for centrifugal washing is aqueous solution and ethanol solution.

Further, the drying temperature is 50-80 deg.C (the temperature is suitable for ethanol volatilization), and the drying time is 6-12 h.

In some embodiments, further comprising subjecting the carbon source oligomer-coated solid microspheres to a heat treatment process: heat treatment is carried out for 3-6h at the temperature of 600-900 ℃ in the inert gas atmosphere.

In some embodiments, the etching is etching with an acid or a base.

Further, the acid is hydrofluoric acid, and the base is sodium hydroxide.

Further, the time of acid or alkali etching is 12-48 h.

Furthermore, the concentration of the hydrofluoric acid solution is 5-10 wt%; the concentration of the sodium hydroxide solution is 10-15 wt%.

In some embodiments, the method further comprises a step of freeze-drying (removing moisture) the etched mesoporous hollow carbon nanospheres.

Further, the freeze-drying time is 12-24 h.

In some embodiments, the active metal source is a soluble salt of Fe, Co, Ni, or the like.

Further, the soluble salt is chloride, nitrate or acetate of Fe, Co, Ni and the like.

Further, the active metal source is impregnated and attached to the mesoporous hollow carbon nanospheres by an isometric impregnation method.

Furthermore, the metal loading on the mesoporous hollow carbon nanospheres is 0.1-8%.

In some embodiments, the method further comprises the step of freeze-drying and heat-treating the prepared mesoporous hollow carbon nanosphere supported metal source (the freeze-drying is to remove moisture, and the heat-treating is to use ammonia gas for nitrogen doping and better anchoring metal).

Further, the freeze-drying time is 12-24 h.

Further, the heat treatment atmosphere is a mixed gas of inert gas and ammonia gas, and the mixing ratio is 2-4: 1.

Further, the temperature of the heat treatment is 600-900 ℃, and the time of the heat treatment is 1-4 h.

In a third aspect, the invention provides the nitrogen-doped mesoporous hollow carbon nanosphere supported metal catalyst prepared by the preparation method.

In a fourth aspect, the invention provides an application of the nitrogen-doped mesoporous hollow carbon nanosphere loaded metal catalyst in electrocatalytic oxygen reduction; especially in the preparation of hydrogen peroxide by electrocatalytic oxygen reduction.

Example 1

1) 1.15ml of tetrapropoxysilane and 1.8ml of ethyl orthosilicate were added to a mixed solution composed of 70ml of ethanol, 10ml of water and 3ml of ammonia water under vigorous stirring, and after 15min, 0.4g of resorcinol and 0.56ml of formalin were added to the above solution and reacted for 24 hours with stirring. The precipitate was then collected by centrifugation and washed three times with water and ethanol and dried overnight at 60 ℃. And finally, roasting the mixture in a tube furnace at 700 ℃ for 5h in nitrogen, cooling the mixture to room temperature, taking the mixture out, grinding the mixture into powder, reacting the powder in 5 wt% hydrofluoric acid for 48h to etch away silicon dioxide, centrifugally washing the powder to be neutral, and freeze-drying the powder for 24h to obtain the mesoporous hollow carbon nanospheres. Immersing mesoporous hollow carbon nanospheres in CoCl in equal volume₂·6H₂Standing overnight in the solution prepared by O to make the mesoporous hollow carbon nanospheres adsorb the cobalt chloride solution, freeze-drying the adsorbed product for 24h and roasting at 750 ℃ for 1h (N₂ 100ml/min+NH₃50ml/min, 20 ℃/min) to obtain the nitrogen-doped mesoporous hollow carbon nanosphere supported Co catalyst, wherein the supported amount of the metal cobalt is 0.5 wt%, and is marked as 0.5% Co-N-C.

2) The catalytic performance of the catalyst was examined using the rotating ring disk electrode of IVIUM and CHI 760E electrochemical workstation. Dispersing 5mg of catalyst in 1ml of mixed solution of water, isopropanol and Nafion, uniformly dispersing by ultrasonic, uniformly dripping 5 mu L of solution on a rotating ring disk electrode, and naturally drying. And then adding 0.1M perchloric acid solution into an electrolytic cell, firstly introducing nitrogen, performing CV and LSV scanning by using an electrochemical workstation, then introducing oxygen, performing CV and LSV scanning, wherein the electrode rotating speed is 1600rpm, the ring electrode potential is 1.2V relative to the reversible hydrogen electrode, and testing the catalyst stability by an i-t curve.

As can be seen from FIG. 2, the specific surface area of the carrier hollow carbon nanosphere of the present invention is higher than 1000m²The pore diameter belongs to mesopores. As can be seen from fig. 3(a), the catalyst of this example has a higher oxygen reduction initiation potential and half-wave potential, and a larger limiting diffusion current; from FIG. 3(b), it can be seen that the catalyst of this example has higher hydrogen peroxide selectivity and lower electron transfer number at high potential; as can be seen from fig. 3(c), the catalyst of this example has excellent electrocatalytic oxygen reduction stability.

Example 2

1) 1.5ml of tetrapropoxysilane and 1.55ml of ethyl orthosilicate were added to a mixed solution composed of 70ml of ethanol, 10ml of water and 3ml of ammonia water under vigorous stirring, and after 15min, 0.4g of resorcinol and 0.56ml of formalin were added to the above solution and reacted for 24 hours with stirring. The precipitate was then collected by centrifugation and washed three times with water and ethanol and dried overnight at 60 ℃. And finally, roasting the mixture in a tube furnace at 700 ℃ for 5h in nitrogen, cooling the mixture to room temperature, taking the mixture out, grinding the mixture into powder, reacting the powder in 5 wt% hydrofluoric acid for 48h to etch away silicon dioxide, centrifugally washing the powder to be neutral, and freeze-drying the powder for 24h to obtain the mesoporous hollow carbon nanospheres. Immersing mesoporous hollow carbon nanospheres in CoCl in equal volume₂·6H₂Standing overnight in the solution prepared by O to make the mesoporous hollow carbon nanospheres adsorb the cobalt chloride solution, freeze-drying the adsorbed product for 24h and roasting at 750 ℃ for 1h (N₂ 100ml/min+NH₃50ml/min, 20 ℃/min) to obtain the nitrogen-doped mesoporous hollow carbon nanosphere supported Co catalyst, wherein the supported amount of the metal cobalt is 1 wt%, and the supported amount is marked as 1% Co-N-C.

2) The catalytic performance of the catalyst was examined using the rotating ring disk electrode of IVIUM and CHI 760E electrochemical workstation. Dispersing 5mg of catalyst in 1ml of mixed solution of water, isopropanol and Nafion, uniformly dispersing by ultrasonic, uniformly dripping 5 mu L of solution on a rotating ring disk electrode, and naturally drying. And then adding 0.1M perchloric acid solution into an electrolytic cell, firstly introducing nitrogen, performing CV and LSV scanning by using an electrochemical workstation, then introducing oxygen until the oxygen is saturated, and performing CV and LSV scanning, wherein the electrode rotating speed is 1600rpm, and the ring electrode potential is 1.2V relative to the reversible hydrogen electrode.

As can be seen from fig. 4(a), the catalyst of this example has a higher oxygen reduction initiation potential and half-wave potential, and a larger limiting diffusion current; as can be seen from fig. 4(b), the catalyst of this example has higher hydrogen peroxide selectivity and lower electron transfer number at high potential.

Example 3

1) 1.5ml of tetrapropoxysilane and 1.55ml of ethyl orthosilicate were added to a solution of 70ml of ethanol, 10ml of water and 3ml of aqueous ammonia under vigorous stirring, and after 15min, 0.4g of resorcinol and 0.56ml of formalin were added to the above solution and reacted for 24 hours with stirring. The precipitate was then collected by centrifugation and washed three times with water and ethanol and dried overnight at 60 ℃. And finally, roasting the mixture in a tube furnace at 700 ℃ for 5h in nitrogen, cooling the mixture to room temperature, taking the mixture out, grinding the mixture into powder, reacting the powder in 5 wt% hydrofluoric acid for 48h to etch away silicon dioxide, centrifugally washing the powder to be neutral, and freeze-drying the powder for 24h to obtain the mesoporous hollow carbon nanospheres. Immersing mesoporous hollow carbon nanospheres in CoCl in equal volume₂·6H₂Standing overnight in the solution prepared by O to make the mesoporous hollow carbon nanospheres adsorb the cobalt chloride solution, freeze-drying the adsorbed product for 24h and roasting at 750 ℃ for 1h (N₂ 100ml/min+NH₃50ml/min, 20 ℃/min) to obtain the nitrogen-doped mesoporous hollow carbon nanosphere supported Co catalyst, wherein the supported amount of the metal cobalt is 4 wt%, and is marked as 4% Co-N-C.

2) The catalytic performance of the catalyst was examined using the rotating ring disk electrode of IVIUM and CHI 760E electrochemical workstation. Dispersing 5mg of catalyst in 1ml of mixed solution of water, isopropanol and Nafion, uniformly dispersing by ultrasonic, uniformly dripping 5 mu L of solution on a rotating ring disk electrode, and naturally drying. And then adding 0.1M perchloric acid solution into an electrolytic cell, firstly introducing nitrogen, performing CV and LSV scanning by using an electrochemical workstation, then introducing oxygen until the oxygen is saturated, and performing CV and LSV scanning, wherein the electrode rotating speed is 1600rpm, and the ring electrode potential is 1.2V relative to the reversible hydrogen electrode.

According to FIG. 1(a), it can be seen that the catalyst of this example has a hollow-shell spherical structure, a diameter of about 200nm, a shell thickness of about 12nm, and a supported metal content of 4%, the Co particles cannot be observed by HRTEM, which indicates that the supported metal Co size of the 4% Co-N-C catalyst of this example is less than 2nm, and may be a single atom or a cluster; as can be seen from fig. 5(a), the catalyst of this example has a higher oxygen reduction initiation potential and half-wave potential, and a larger limiting diffusion current; as can be seen from fig. 5(b), the catalyst of this example has higher hydrogen peroxide selectivity and lower electron transfer number at high potential.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.