Carbon nanotube catalyst and method for preparing the same

Abstract

The application relates to the technical field of catalysts, and particularly discloses a carbon nanotube catalyst and a preparation method thereof. The carbon nanotube catalyst is modified carbon nanotubes obtained by mixing and treating purified carbon nanotubes with composite acid, and is prepared by grafting graphene on the surface of the modified carbon nanotubes through a ball milling process. The modified carbon nanotubes are obtained by chemically modifying the carbon nanotubes with the composite acid, so that the carbon nanotubes carry a large number of active groups and have the recognition function for purines, and the adsorption of the purines can be improved. The active groups include carboxyl and hydroxyl. In addition, the carbon nanotube catalyst is prepared by grafting graphene on the surface of the modified carbon nanotubes through the ball milling process, the adsorption of the purines is further improved under the action of the graphene, the effective adsorption of the purines is realized, and the sensitivity in the detection of the purines is remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of catalysts, in particular to a carbon nanotube catalyst and a preparation method thereof. BACKGROUND

[0002] Carbon nanotubes are a special carbon material, which has an active surface and a highly crystalline structure, making it a very excellent catalyst. In recent years, carbon nanotube catalysts have received widespread attention in the fields of chemical reactions, electrochemical catalysis, photocatalysis, etc.

[0003] Due to the excellent electrocatalytic performance, good biocompatibility, and large specific surface area of carbon nanotubes, they can be used to make bioelectrochemical sensors after being modified on the surface. The application of nanomaterials in the preparation of sensors can improve the response performance of the sensors. Existing biosensors can be used to detect uric acid and purines. Metabolic disorders of purines lead to uric acid deposition, which is the direct cause and most important risk factor of hyperuricemia and gout, and is accompanied by metabolic syndromes such as diabetes, hyperlipidemia, and hypertension. However, the existing carbon nanotube catalysts have low sensitivity when detecting purines. SUMMARY

[0004] In view of the defects of the prior art, the purpose of the present application is to provide a carbon nanotube catalyst and a preparation method thereof to solve the problems raised in the background art.

[0005] The technical problems solved by the present application are solved by the following technical solutions:

[0006] The present application provides a carbon nanotube catalyst, which is obtained by mixing and treating purified carbon nanotubes with a composite acid to obtain modified carbon nanotubes, and then grafting graphene on the surface of the modified carbon nanotubes using a ball milling process.

[0007] As a further technical solution of the present application, the preparation method of the purified carbon nanotubes comprises the following steps:

[0008] The nanocarbon tubes are placed in air at 500-600℃ for oxidation and crystallization removal, a nitric acid solution with a volume fraction of 20-30% is added, and stirring and mixing is performed for 1-3h, then deionized water is used for washing until the PH is neutral, filtration and drying are performed to obtain the purified carbon nanotubes.

[0009] As a further technical solution of the present application, the preparation method of the modified carbon nanotubes comprises the following steps:

[0010] The purified nanocarbon tubes are placed in a composite acid for ultrasonic mixing and treatment for 1-2h, then deionized water is used for washing until the PH is neutral, filtration and drying are performed to obtain the modified nanocarbon tubes.

[0011] As a further technical scheme of the present application, the composite acid is obtained by mixing concentrated nitric acid and concentrated sulfuric acid in a volume ratio of 1:2.5-3.5, and the mass concentration of the concentrated nitric acid and the concentrated sulfuric acid reaches 96%.

[0012] As a further technical scheme of the present application, the power of the ultrasonic mixing treatment is 100-200w.

[0013] As a further technical scheme of the present application, the process of grafting graphene on the surface of the modified carbon nanotube by using the ball milling process comprises the following steps:

[0014] The modified carbon nanotube is sent into a grinding machine for grinding, then 6-10% of the total weight of the modified carbon nanotube of grinding liquid is added, and the grinding is carried out at a rotating speed of 800-1200r / min for 30-40min. After the grinding is completed, the grinding material is obtained, and the grinding material is dried.

[0015] As a further technical scheme of the present application, the grinding liquid comprises the following raw materials in parts by weight: graphene 1-10 parts, sodium dodecyl benzene sulfonate 2-5 parts, and deionized water 60-80 parts; and the preparation method of the grinding liquid comprises the following steps:

[0016] The sodium dodecyl benzene sulfonate 2-5 parts and the deionized water 60-80 parts are stirred and mixed uniformly, then the graphene 1-10 parts and the silane coupling agent 0.5-0.8 parts are added, and the stirring and mixing are fully carried out, so as to obtain the grinding liquid.

[0017] Another object of the embodiment of the present application is to provide a preparation method of a carbon nanotube catalyst, which comprises the following steps:

[0018] S01, the nanometer carbon tube is placed in 500-600℃ air for oxidation and crystallization removal, a nitric acid solution with a volume fraction of 20-30% is added, stirring and mixing is carried out for 1-3h, then deionized water is used for washing until the PH is neutral, filtration and drying are carried out to obtain the purified carbon nanotube;

[0019] S02, the purified nanometer carbon tube is placed into the composite acid for ultrasonic mixing treatment for 1-2h, then deionized water is used for washing until the PH is neutral, filtration and drying are carried out to obtain the modified nanometer carbon tube;

[0020] S03, the modified carbon nanotube is sent into a grinding machine for grinding, then 6-10% of the total weight of the modified carbon nanotube of grinding liquid is added, and the grinding is carried out at a rotating speed of 800-1200r / min for 30-40min. After the grinding is completed, the grinding material is obtained, and the grinding material is dried.

[0021] Compared with the prior art, the present application has the following beneficial effects:

[0022] The application provides a carbon nanotube catalyst and a preparation method thereof. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the application will be clearly and completely described below with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the application.

[0024] The application provides a carbon nanotube catalyst, which is prepared by mixing and treating purified carbon nanotubes with a composite acid to obtain modified carbon nanotubes, and grafting graphene on the surface of the modified carbon nanotubes by using a ball milling process.

[0025] In the embodiments of the application, the preparation method of the purified carbon nanotubes comprises the following steps:

[0026] The nanometer carbon tubes are placed in air at 500-600 DEG C for oxidation and crystallization removal, a nitric acid solution with a volume fraction of 20-30% is added, and stirring and mixing are performed for 1-3 h, then deionized water is used for washing until the PH is neutral, filtration is performed, and drying is performed to obtain the purified carbon nanotubes.

[0027] In the embodiments of the application, the preparation method of the modified carbon nanotubes comprises the following steps:

[0028] The purified nanometer carbon tubes are placed in the composite acid for ultrasonic mixing treatment for 1-2 h, then deionized water is used for washing until the PH is neutral, filtration is performed, and drying is performed to obtain the modified nanometer carbon tubes.

[0029] In the embodiments of the application, the composite acid is obtained by mixing concentrated nitric acid and concentrated sulfuric acid in a volume ratio of 1:2.5-3.5, and the mass concentration of the concentrated nitric acid and the concentrated sulfuric acid reaches 96%.

[0030] In the embodiments of the application, the power of the ultrasonic mixing treatment is 100-200 W.

[0031] In the embodiment of the present application, the process for grafting graphene on the surface of modified carbon nanotubes by using the ball milling process comprises the following steps:

[0032] The modified carbon nanotubes are sent into a grinding machine for grinding, then 6-10% of the grinding liquid based on the total weight of the modified carbon nanotubes is added, and the grinding is carried out at a rotating speed of 800-1200 r / min for 30-40 min. After the grinding is completed, the grinding material is obtained, and the grinding material is dried.

[0033] In the embodiment of the present application, the grinding liquid comprises the following raw materials in parts by weight: graphene 1-10 parts, sodium dodecyl benzene sulfonate 2-5 parts, and deionized water 60-80 parts; and the preparation method of the grinding liquid comprises the following steps:

[0034] The sodium dodecyl benzene sulfonate 2-5 parts and the deionized water 60-80 parts are stirred and uniformly mixed, then the graphene 1-10 parts and the silane coupling agent 0.5-0.8 parts are added and stirred and mixed sufficiently to obtain the grinding liquid.

[0035] Another object of the embodiment of the present application is to provide a preparation method of carbon nanotube catalyst, comprising the following steps:

[0036] S01, the nanometer carbon tube is placed in 500-600℃ air for oxidation and crystallization removal, a nitric acid solution with a volume fraction of 20-30% is added, and stirring and mixing is carried out for 1-3h, then deionized water is used for washing to make the PH neutral, filtration is carried out, and drying is carried out to obtain the purified carbon nanotube;

[0037] S02, the purified nanometer carbon tube is placed into a composite acid for ultrasonic mixing treatment for 1-2h, then deionized water is used for washing to make the PH neutral, filtration is carried out, and drying is carried out to obtain the modified nanometer carbon tube;

[0038] S03, the modified carbon nanotube is sent into a grinding machine for grinding, then 6-10% of the grinding liquid based on the total weight of the modified carbon nanotube is added, and the grinding is carried out at a rotating speed of 800-1200 r / min for 30-40 min. After the grinding is completed, the grinding material is obtained, and the grinding material is dried.

[0039] Embodiment 1.

[0040] In the embodiment of the present application, the preparation method of the purified carbon nanotube comprises the following steps:

[0041] The nanometer carbon tube is placed in 500℃ air for oxidation and crystallization removal, a nitric acid solution with a volume fraction of 20% is added, stirring and mixing is carried out for 1h, then deionized water is used for washing to make the PH neutral, filtration is carried out, and drying is carried out to obtain the purified carbon nanotube.

[0042] In the embodiment of the present application, the preparation method of the modified carbon nanotube comprises the following steps:

[0043] The purified carbon nanotube 50 mg is placed in the composite acid 50 ml for ultrasonic mixing treatment for 1-2 h, and then washed with deionized water until the PH is neutral, filtered, and dried to obtain the modified carbon nanotube.

[0044] In the embodiment of the present application, the composite acid is obtained by mixing concentrated nitric acid and concentrated sulfuric acid in a volume ratio of 1:2.5-3.5, and the mass concentration of the concentrated nitric acid and the concentrated sulfuric acid reaches 96%.

[0045] In the embodiment of the present application, the power of the ultrasonic mixing treatment is 100 w.

[0046] In the embodiment of the present application, the process of grafting graphene on the surface of the modified carbon nanotube by using the ball milling process comprises the following steps:

[0047] The modified carbon nanotube is sent into a grinding machine for grinding, and then 6% of the total weight of the modified carbon nanotube is added as a grinding liquid, and the grinding is carried out at a rotating speed of 800 r / min for 30 min. After the grinding is completed, a grinding material is obtained, and the grinding material is dried.

[0048] In the embodiment of the present application, the grinding liquid comprises the following raw materials in parts by weight: graphene 4 parts, sodium dodecyl benzene sulfonate 2 parts, and deionized water 60 parts; and the preparation method of the grinding liquid comprises the following steps:

[0049] The sodium dodecyl benzene sulfonate 2 parts and the deionized water 60 parts are stirred and uniformly mixed, and then the graphene 4 parts and the silane coupling agent 0.5 part are added and stirred and mixed sufficiently to obtain the grinding liquid.

[0050] Another object of the embodiment of the present application is to provide a preparation method of a carbon nanotube catalyst, comprising the following steps:

[0051] S01, the carbon nanotube is placed in air at 500 DEG C for oxidation and crystallization removal, a nitric acid solution with a volume fraction of 20% is added, and stirred and mixed for 1 h, and then deionized water is used for washing until the PH is neutral, and the purified carbon nanotube is obtained by filtering and drying;

[0052] S02, the purified carbon nanotube 50 mg is placed in the composite acid 50 ml for ultrasonic mixing treatment for 1 h, and then washed with deionized water until the PH is neutral, filtered, and dried to obtain the modified carbon nanotube;

[0053] S03, the modified carbon nanotubes are sent into a grinder for grinding, then 6% of the total weight of the modified carbon nanotubes of grinding fluid is added, and the grinding is carried out at a rotating speed of 800 r / min for 30 min, and the grinding is completed to obtain a grinding material, and the grinding material is subjected to freezing and drying to obtain carbon nanotube catalysts.

[0054] Example 2.

[0055] In the embodiment of the present application, the preparation method of the purified carbon nanotubes comprises the following steps:

[0056] The nanometer carbon tubes are placed in air at 600℃ for oxidation and crystallization removal, a nitric acid solution with a volume fraction of 30% is added, and stirring and mixing are carried out for 3 h, then deionized water is used for washing until the PH is neutral, and filtration and drying are carried out to obtain the purified carbon nanotubes.

[0057] In the embodiment of the present application, the preparation method of the modified carbon nanotubes comprises the following steps:

[0058] The purified nanometer carbon tubes 40 mg are placed in a composite acid 60 ml for ultrasonic mixing treatment for 2 h, then deionized water is used for washing until the PH is neutral, and filtration and drying are carried out to obtain the modified nanometer carbon tubes.

[0059] In the embodiment of the present application, the composite acid is obtained by mixing concentrated nitric acid and concentrated sulfuric acid in a volume ratio of 1:3.5, and the mass concentration of the concentrated nitric acid and the concentrated sulfuric acid reaches 96%.

[0060] In the embodiment of the present application, the power of the ultrasonic mixing treatment is 200 w.

[0061] In the embodiment of the present application, the process of grafting graphene on the surface of the modified carbon nanotubes by using the ball milling process comprises the following steps:

[0062] The modified carbon nanotubes are sent into a grinder for grinding, then 10% of the total weight of the modified carbon nanotubes of grinding fluid is added, and the grinding is carried out at a rotating speed of 1200 r / min for 40 min, and the grinding is completed to obtain a grinding material, and the grinding material is subjected to drying.

[0063] In the embodiment of the present application, according to weight parts, the grinding fluid comprises the following raw materials: 4 parts of graphene, 5 parts of sodium dodecyl benzene sulfonate and 80 parts of deionized water; and the preparation method of the grinding fluid comprises the following steps:

[0064] The sodium dodecyl benzene sulfonate 5 parts and the deionized water 80 parts are uniformly stirred and mixed, then the graphene 4 parts and the silane coupling agent 0.8 parts are added, and stirring and mixing are carried out sufficiently to obtain the grinding fluid.

[0065] Another object of the embodiment of the present application is to provide a preparation method of carbon nanotube catalysts, comprising the following steps:

[0066] S01, placing the carbon nanotubes in 600℃ air for oxidation and crystallization removal, adding a 30% volume fraction nitric acid solution, stirring and mixing for 3h, then washing with deionized water to make the PH neutral, filtering, and drying to obtain purified carbon nanotubes;

[0067] S02, placing 50mg of the purified carbon nanotubes into 50ml of a composite acid for ultrasonic mixing treatment for 2h, then washing with deionized water until the PH is neutral, filtering, drying, and obtaining modified carbon nanotubes;

[0068] S03, sending the modified carbon nanotubes into a grinder for grinding, then adding a grinding liquid of 10% of the total weight of the modified carbon nanotubes, grinding at a speed of 1200r / min for 40min, obtaining a grinding material after grinding, and freezing and drying the grinding material to obtain a carbon nanotube catalyst.

[0069] Example 3.

[0070] In the embodiment of the present application, the preparation method of the purified carbon nanotubes comprises the following steps:

[0071] placing the carbon nanotubes in 550℃ air for oxidation and crystallization removal, adding a 25% volume fraction nitric acid solution, stirring and mixing for 2h, then washing with deionized water to make the PH neutral, filtering, and drying to obtain purified carbon nanotubes.

[0072] In the embodiment of the present application, the preparation method of the modified carbon nanotubes comprises the following steps:

[0073] placing 50mg of the purified carbon nanotubes into 50ml of a composite acid for ultrasonic mixing treatment for 2h, then washing with deionized water until the PH is neutral, filtering, drying, and obtaining modified carbon nanotubes.

[0074] In the embodiment of the present application, the composite acid is obtained by mixing concentrated nitric acid and concentrated sulfuric acid in a volume ratio of 1:3, and the mass concentration of the concentrated nitric acid and the concentrated sulfuric acid reaches 96%.

[0075] In the embodiment of the present application, the power of the ultrasonic mixing treatment is 160w.

[0076] In the embodiment of the present application, the process of grafting graphene on the surface of the modified carbon nanotubes by using a ball milling process comprises the following steps:

[0077] sending the modified carbon nanotubes into a grinder for grinding, then adding a grinding liquid of 8% of the total weight of the modified carbon nanotubes, grinding at a speed of 1000r / min for 30min, obtaining a grinding material after grinding, and drying the grinding material.

[0078] In the embodiment of the present application, the grinding liquid comprises the following raw materials in parts by weight: 4 parts of graphene, 3 parts of sodium dodecyl benzene sulfonate and 80 parts of deionized water; and the preparation method of the grinding liquid comprises the following steps:

[0079] The 3 parts of sodium dodecyl benzene sulfonate and 80 parts of deionized water are stirred and uniformly mixed, then 4 parts of graphene and 0.5 parts of silane coupling agent are added and stirred and mixed sufficiently to obtain the grinding liquid.

[0080] Another object of the embodiment of the present application is to provide a preparation method of carbon nanotube catalyst, comprising the following steps:

[0081] S01, placing the nanometer carbon tube in air at 550℃ for oxidation and crystallization removal, adding a 25% volume fraction of nitric acid solution, stirring and mixing for 2 hours, then washing with deionized water to neutralize the PH, filtering and drying to obtain the purified carbon nanotube;

[0082] S02, placing 50mg of the purified nanometer carbon tube into 50ml of composite acid for ultrasonic mixing treatment for 2 hours, then washing with deionized water to neutralize the PH, filtering and drying to obtain the modified nanometer carbon tube;

[0083] S03, feeding the modified carbon nanotube into a grinding machine for grinding, then adding a grinding liquid with a total weight of 8% of the modified carbon nanotube, and grinding at a speed of 1000r / min for 30 minutes, then obtaining the grinding material, drying the grinding material, and obtaining the carbon nanotube catalyst.

[0084] Embodiment 4

[0085] In the embodiment of the present application, the preparation method of the purified carbon nanotube comprises the following steps:

[0086] S01, placing the nanometer carbon tube in air at 550℃ for oxidation and crystallization removal, adding a 25% volume fraction of nitric acid solution, stirring and mixing for 2 hours, then washing with deionized water to neutralize the PH, filtering and drying to obtain the purified carbon nanotube.

[0087] In the embodiment of the present application, the preparation method of the modified carbon nanotube comprises the following steps:

[0088] S02, placing 50mg of the purified nanometer carbon tube into 50ml of composite acid for ultrasonic mixing treatment for 2 hours, then washing with deionized water to neutralize the PH, filtering and drying to obtain the modified nanometer carbon tube.

[0089] In the embodiment of the present application, the composite acid is obtained by mixing concentrated nitric acid and concentrated sulfuric acid in a volume ratio of 1:3, and the mass concentration of the concentrated nitric acid and the concentrated sulfuric acid reaches 96%.

[0090] In the embodiment of the present application, the power of the ultrasonic mixing treatment is 160w.

[0091] In the embodiment of the present application, the process of grafting graphene on the surface of the modified carbon nanotube by using the ball milling process comprises the following steps:

[0092] The modified carbon nanotube is sent into a grinder for grinding, then 8% of the total weight of the modified carbon nanotube is added into the grinder as a grinding liquid, and the grinding is carried out at a rotating speed of 1000r / min for 30min, and then the grinding is completed to obtain a grinding material, and the grinding material is dried.

[0093] In the embodiment of the present application, the grinding liquid comprises the following raw materials in terms of weight parts: 1 part of graphene, 3 parts of sodium dodecyl benzene sulfonate and 80 parts of deionized water; and the preparation method of the grinding liquid comprises the following steps:

[0094] The 3 parts of sodium dodecyl benzene sulfonate and the 80 parts of deionized water are stirred and mixed uniformly, then 1 part of graphene and 0.5 part of silane coupling agent are added and stirred and mixed sufficiently to obtain the grinding liquid.

[0095] Another object of the embodiment of the present application is to provide a preparation method of a carbon nanotube catalyst, which comprises the following steps:

[0096] S01, the nanometer carbon tube is placed in air at 550℃ for oxidation and crystallization removal, a 25% nitric acid solution is added, stirred and mixed for 2h, then deionized water is used for washing to make the PH neutral, filtered, and dried to obtain the purified carbon nanotube;

[0097] S02, the purified nanometer carbon tube 50mg is put into a composite acid 50ml for ultrasonic mixing treatment for 2h, then deionized water is used for washing to make the PH neutral, filtered, and dried to obtain the modified nanometer carbon tube;

[0098] S03, the modified carbon nanotube is sent into a grinder for grinding, then 8% of the total weight of the modified carbon nanotube is added into the grinder as a grinding liquid, and the grinding is carried out at a rotating speed of 1000r / min for 30min, and then the grinding is completed to obtain a grinding material, and the grinding material is dried to obtain the carbon nanotube catalyst.

[0099] Example 5

[0100] In the embodiment of the present application, the preparation method of the purified carbon nanotube comprises the following steps:

[0101] The nanometer carbon tube is placed in air at 550℃ for oxidation and crystallization removal, a 25% nitric acid solution is added, stirred and mixed for 2h, then deionized water is used for washing to make the PH neutral, filtered, and dried to obtain the purified carbon nanotube.

[0102] In the embodiment of the present application, the preparation method of the modified carbon nanotube comprises the following steps:

[0103] The purified carbon nanotube 50 mg is placed in the composite acid 50 ml for ultrasonic mixing treatment for 2 h, then washed with deionized water until the PH is neutral, filtered, dried, and the modified carbon nanotube is obtained.

[0104] In the embodiment of the present application, the composite acid is obtained by mixing concentrated nitric acid and concentrated sulfuric acid in a volume ratio of 1:3, and the mass concentration of the concentrated nitric acid and the concentrated sulfuric acid reaches 96%.

[0105] In the embodiment of the present application, the power of the ultrasonic mixing treatment is 160 w.

[0106] In the embodiment of the present application, the process of grafting graphene on the surface of the modified carbon nanotube by using the ball milling process comprises the following steps:

[0107] The modified carbon nanotube is sent into a grinding machine for grinding, then 8% of the total weight of the modified carbon nanotube of grinding liquid is added, and the grinding is carried out at a rotating speed of 1000 r / min for 30 min, and the grinding material is obtained after the grinding is completed, and the grinding material is dried.

[0108] In the embodiment of the present application, according to the weight parts, the grinding liquid comprises the following raw materials: graphene 8 parts, sodium dodecyl benzene sulfonate 3 parts and deionized water 80 parts; and the preparation method of the grinding liquid comprises the following steps:

[0109] The sodium dodecyl benzene sulfonate 3 parts and the deionized water 80 parts are stirred and mixed uniformly, then the graphene 8 parts and the silane coupling agent 0.5 parts are added, and the stirring and mixing are fully carried out, and the grinding liquid is obtained.

[0110] Another object of the embodiment of the present application is to provide a preparation method of a carbon nanotube catalyst, comprising the following steps:

[0111] S01, the carbon nanotube is placed in air at 550 DEG C for oxidation and crystallization removal, a nitric acid solution with a volume fraction of 25% is added, stirring and mixing for 2 h, then deionized water is used for washing until the PH is neutral, filtering, drying, and the purified carbon nanotube is obtained;

[0112] S02, the purified carbon nanotube 50 mg is placed in the composite acid 50 ml for ultrasonic mixing treatment for 2 h, then washed with deionized water until the PH is neutral, filtered, dried, and the modified carbon nanotube is obtained.

[0113] S03, the modified carbon nanotubes are sent into a grinder for grinding, then 8% of the total weight of the modified carbon nanotubes of grinding fluid is added, and the grinding is carried out at a rotating speed of 1000 r / min for 30 min. After the grinding is completed, the grinding material is obtained. The grinding material is dried to obtain the carbon nanotube catalyst.

[0114] Comparative Example 1.

[0115] Different from Example 3 is that the carbon nanotubes after purification are not subjected to the composite acid modification treatment.

[0116] Comparative Example 2.

[0117] Different from Example 3 is that the modified carbon nanotubes are not subjected to the ball milling process treatment, and are directly used as the carbon nanotube catalyst.

[0118] Comparative Example 3

[0119] Different from Example 3 is that the graphene is not added in the ball milling process.

[0120] The carbon nanotube catalysts prepared in Examples 1-5 and Comparative Examples 1-3 are made into carbon nanotube membranes, which are applied to the measurement of guanine. The concentration of guanine is 0.03 g / L. The guanine is dropped on the carbon nanotube membranes made of the carbon nanotube catalysts prepared in Examples 1-5 and Comparative Examples 1-4, and after vacuum drying, the voltammetric characteristic curve is measured. The resistance before adsorption and the resistance after adsorption are calculated from the voltammetric characteristic curve, and the results are shown in Table 1.

[0121] Table 1

[0122] Group Resistance before adsorption (Ω) Resistance after adsorption (Ω) Example 1 85 803 Example 2 92 1186 Example 3 96 1295 Example 4 99 1299 Example 5 93 1197 Comparative Example 1 80 350 Comparative Example 2 71 655 Comparative Example 3 73 760

[0123] From the experimental data of Examples 1-5 and Comparative Examples 1-3, it can be seen that the carbon nanotube catalyst prepared in the examples can effectively improve the adsorption of purine compared with the carbon nanotube catalyst prepared in Comparative Examples 1-3. The sensitivity to purine can be calculated by (resistance after adsorption-resistance before adsorption) / resistance before adsorption. According to the experimental data of the present application, it can be seen that the sensitivity to purine can be significantly improved by using composite acid to chemically modify the carbon nanotubes and by using the ball milling process to treat the modified carbon nanotubes.

[0124] It is apparent for those skilled in the art that the present application is not limited to the details of the foregoing exemplary embodiments, and that the present application can be implemented in other particular forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be considered in all respects as illustrative and not restrictive, and the scope of the present application should be defined by the appended claims rather than the above description, and all changes coming within the meaning and equivalency range of the claims are intended to be embraced therein.

[0125] Furthermore, it should be understood that although the specification is described in terms of embodiments, not every embodiment includes only one independent technical solution, and the specification is described in this way only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that those skilled in the art can understand.

Claims

1. A carbon nanotube catalyst, characterized by, The carbon nanotube catalyst is prepared by mixing the purified carbon nanotube with a complex acid to obtain modified carbon nanotube, and then grafting graphene on the surface of the modified carbon nanotube by using a ball milling process. The preparation method of the purified carbon nanotube comprises the following steps: The nanometer carbon tube is placed in air at 500-600℃ for oxidation and crystallization removal, a nitric acid solution with a volume fraction of 20-30% is added, and stirring and mixing are performed for 1-3h, then deionized water is used for washing until the pH is neutral, filtration and drying are performed to obtain the purified carbon nanotube; The process for grafting graphene on the surface of the modified carbon nanotube by using a ball milling process comprises the following steps: The modified carbon nanotube is sent into a grinding machine for grinding, then a grinding liquid accounting for 6-10% of the total weight of the modified carbon nanotube is added, and grinding is performed at a rotating speed of 800-1200r / min for 30-40min, and then the grinding is completed to obtain a grinding material, and the grinding material is dried. According to weight parts, the grinding liquid comprises the following raw materials: 1-10 parts of graphene, 2-5 parts of sodium dodecyl benzene sulfonate and 60-80 parts of deionized water; and the preparation method of the grinding liquid comprises the following steps: The sodium dodecyl benzene sulfonate 2-5 parts and the deionized water 60-80 parts are stirred and mixed uniformly, then the graphene 1-10 parts and the silane coupling agent 0.5-0.8 parts are added and stirred and mixed sufficiently to obtain the grinding liquid. The prepared carbon nanotube catalyst is made into a carbon nanotube film and applied to the measurement of guanine.

2. The carbon nanotube catalyst according to claim 1, characterized in that, The preparation method of the modified carbon nanotube comprises the following steps: The purified nanometer carbon tube is placed in a complex acid for ultrasonic mixing treatment for 1-2h, then deionized water is used for cleaning until the pH is neutral, filtration and drying are performed to obtain the modified nanometer carbon tube.

3. The carbon nanotube catalyst of claim 2, wherein the catalyst is a catalyst selected from the group consisting of Fe, Co, Ni, Mo, W, Ru, Rh, Pd, Ag, Ir, Pt, Au, and mixtures thereof. The complex acid is obtained by mixing concentrated nitric acid and concentrated sulfuric acid in a volume ratio of 1:2.5-3.5, and the mass concentration of the concentrated nitric acid and the concentrated sulfuric acid reaches 96%.

4. The carbon nanotube catalyst of claim 2, wherein the catalyst is a catalyst selected from the group consisting of Fe, Co, Ni, Mo, W, Ru, Rh, Pd, Ag, Ir, Pt, Au, and mixtures thereof. The power of the ultrasonic mixing treatment is 100-200w.

5. A method for preparing a carbon nanotube catalyst as described in claim 1, characterized in that, The method comprises the following steps: S01, the nanometer carbon tube is placed in air at 500-600℃ for oxidation and crystallization removal, a nitric acid solution with a volume fraction of 20-30% is added, and stirring and mixing are performed for 1-3h, then deionized water is used for washing until the pH is neutral, filtration and drying are performed to obtain the purified carbon nanotube; S02, the purified nanometer carbon tube is placed in a complex acid for ultrasonic mixing treatment for 1-2h, then deionized water is used for cleaning until the pH is neutral, filtration and drying are performed to obtain the modified nanometer carbon tube; S03, the modified carbon nanotube is sent into a grinding machine for grinding, then a grinding liquid accounting for 6-10% of the total weight of the modified carbon nanotube is added, and grinding is performed at a rotating speed of 800-1200r / min for 30-40min, and then the grinding is completed to obtain a grinding material, and the grinding material is dried.