A heteroatom-doped carbon dot, a preparation method thereof and a functionalized carbon dot

Abstract

The application provides a heteroatom-doped carbon dot, a preparation method thereof and a functionalized carbon dot. The heteroatom-doped carbon dot is an N atom-doped carbon dot or an N, S atom-doped carbon dot; and the functionalized carbon dot is obtained by grafting an ionic liquid on the heteroatom-doped carbon dot. The heteroatom-doped carbon dot and the functionalized carbon dot have excellent corrosion inhibition performance.

Description

Technical Field

[0001] This invention belongs to the field of metal corrosion protection technology, and particularly relates to a heteroatom-doped carbon dot, its preparation method and functionalized carbon dot. Background Technology

[0002] In today's era of rapid industrial technological development, corrosion has become a major global concern. Corrosion causes enormous losses to industries such as oil and gas, water transport, construction, automotive, and transportation. Every year, one-third of steel is replaced due to corrosion failure, resulting in economic losses of approximately 3% of GDP.

[0003] Among various corrosion prevention processes, corrosion inhibitors are the most economical and convenient. However, with increasing environmental and energy-saving awareness, the drawbacks of traditional corrosion inhibitors, such as high toxicity, high cost, and environmental pollution, are becoming increasingly apparent. More and more researchers are dedicated to developing and producing more environmentally friendly, economical, and efficient corrosion inhibitors. Carbon dots, due to their environmental friendliness, low cost, and low toxicity, are widely used in various industries and represent a highly promising corrosion inhibitor. However, the corrosion inhibition performance of carbon dot corrosion inhibitors has not yet reached a high level, and their corrosion inhibition mechanism is still unclear, necessitating modification to improve their corrosion inhibition performance. Summary of the Invention

[0004] One aspect of the present invention provides a method for preparing heteroatom-doped carbon dots, comprising the following steps:

[0005] The carbon-heteroatom source is heated, or a mixture of carbon and heteroatom sources is heated to carry out the first reaction, followed by purification, to obtain the heteroatom-doped carbon dots.

[0006] In one specific embodiment, the heteroatom in the heteroatom-doped carbon point is an N atom and / or an S atom;

[0007] Preferably, the doping rate of the N atoms is 12.27 wt% to 15.13 wt%; and / or the doping rate of the sulfur atoms is 0.13 wt% to 0.21 wt%.

[0008] Preferably, the sulfur atom doping rate is 0.21 wt%.

[0009] In one specific embodiment, the carbon-heteroatom source is a carbon-nitrogen atom source; the carbon source is citric acid; and the heteroatom source is a nitrogen-sulfur source.

[0010] Preferably, the carbon-nitrogen atom source is ammonium citrate;

[0011] Preferably, the nitrogen-sulfur source is thiourea.

[0012] In one specific embodiment, the mass ratio of the carbon source to the heteroatom source is 1:2;

[0013] Preferably, the carbon source and the heteroatom source are dissolved in a first solvent, mixed, and then heated to carry out the first reaction;

[0014] Preferably, the amount of the first solvent is sufficient to dissolve the carbon source and the heteroatom source;

[0015] Preferably, the first solvent is water.

[0016] In one specific embodiment, the first reaction is carried out at 180°C to 200°C for 2 to 4 hours.

[0017] In one specific embodiment, the product obtained from the first reaction is purified according to the following steps:

[0018] 1) Disperse the product obtained from the first reaction in a second solvent, centrifuge, and obtain a supernatant containing the heteroatom-doped carbon dots;

[0019] 2) Dialyze the supernatant using a dialysis bag to obtain a first retention solution containing the heteroatom-doped carbon dots;

[0020] 3) Filter the first retention solution to obtain heteroatom-doped carbon dot solids;

[0021] 4) The heteroatom-doped carbon dot solid is dried to obtain the heteroatom-doped carbon dot;

[0022] Preferably, the molecular weight cutoff of the dialysis bag is 500 Da;

[0023] Preferably, a PVDF membrane with a pore size of 0.22 μm is used for the filtration;

[0024] Preferably, the drying conditions for the heteroatom-doped carbon dot solid are vacuum drying at 60°C for 24 hours;

[0025] Preferably, the second solvent is water.

[0026] The second invention provides a heteroatom-doped carbon dot prepared by the method described in the first invention.

[0027] In one specific embodiment, the particle size of the heteroatom-doped carbon dots is 7 nm to 8 nm.

[0028] The third invention provides a functionalized carbon dot, the structure of which includes heteroatom-doped carbon dots and an ionic liquid, wherein the ionic liquid is grafted onto the heteroatom-doped carbon dots;

[0029] The heteroatom-doped carbon dots are heteroatom-doped carbon dots prepared by the method described in one of the present inventions or heteroatom-doped carbon dots described in another of the present inventions;

[0030] Preferably, the ionic liquid is a terminal aminoimidazole ionic liquid.

[0031] In one specific embodiment, the mass ratio of the heteroatom-doped carbon dots to the ionic liquid is 0.002:1;

[0032] and / or

[0033] The ionic liquid is 1-hexyl-3-aminopropyl-imidazolium bromide.

[0034] In one specific embodiment, the particle size of the functionalized carbon dots is 7 nm to 8 nm.

[0035] The fourth invention provides a method for preparing functionalized carbon dots as described in the third invention, comprising the following steps:

[0036] (1) Mix the heteroatom-doped carbon dots with a third solvent to obtain a heteroatom-doped carbon dot solution;

[0037] (2) The ionic liquid and the fourth solvent are mixed to obtain an ionic liquid solution;

[0038] (3) Mix the heteroatom-doped carbon dot solution and the ionic liquid solution to carry out a second reaction to obtain the crude product of the functionalized carbon dots;

[0039] (4) The crude product of the functionalized carbon dots is purified to obtain the functionalized carbon dots.

[0040] In one specific embodiment, the mass ratio of the heteroatom-doped carbon dots to the ionic liquid is 0.002:1;

[0041] Preferably, the third solvent is water; and / or the fourth solvent is ethanol;

[0042] Preferably, the second reaction is carried out under the condition of stirring for 12 hours.

[0043] In one specific embodiment, the heteroatom-doped carbon dots, the catalyst, and the third solvent are mixed to obtain the heteroatom-doped carbon dot solution; and / or

[0044] The ionic liquid, triethylamine, and a fourth solvent are mixed to obtain the ionic liquid solution;

[0045] Preferably, the mass ratio of the catalyst to the heteroatom-doped carbon dots is 500:1;

[0046] Preferably, the mass ratio of triethylamine to ionic liquid is 0.364:1;

[0047] Preferably, the catalyst is 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride;

[0048] Preferably, the amount of the third solvent is sufficient to dissolve the heteroatom-doped carbon dots and the catalyst; and / or

[0049] The amount of the fourth solvent is sufficient to dissolve the ionic liquid and triethylamine.

[0050] In one specific embodiment, the ionic liquid is prepared by the following method:

[0051] 1-(3-aminopropyl)imidazolium and 1-bromohexane were mixed and subjected to a third reaction, followed by purification to obtain the ionic liquid.

[0052] Preferably, the molar ratio of 1-(3-aminopropyl)imidazole to 1-bromohexane is 1:1;

[0053] Preferably, the 1-(3-aminopropyl)imidazolium and 1-bromohexane are mixed in a fifth solvent; and / or

[0054] The fifth solvent is ethanol;

[0055] Preferably, the amount of the fifth solvent is sufficient to dissolve the 1-(3-aminopropyl)imidazolium and 1-bromohexane;

[0056] Preferably, the third reaction is carried out under the condition of stirring at 90°C for 24 hours;

[0057] Preferably, the product obtained from the third reaction is purified in the following manner:

[0058] a. Mix the product obtained from the third reaction with the sixth solvent, carry out the fourth reaction, filter, and obtain a filtrate containing the ionic liquid;

[0059] b. Evaporate the filtrate to obtain the ionic liquid;

[0060] Preferably, the sixth solvent is a mixture of ethyl acetate and ethanol; and / or

[0061] The mass ratio of ethyl acetate to ethanol is (1 to 2):(1 to 2);

[0062] Preferably, the mass ratio of ethyl acetate to ethanol is 1:2;

[0063] Preferably, the evaporation is vacuum evaporation; and / or the evaporation temperature is 60°C.

[0064] In one specific embodiment, in step (4), the crude product of the functionalized carbon dots is purified by the following method:

[0065] A. The crude product containing the functionalized carbon dots is filtered to obtain a solid mixture containing the functionalized carbon dots;

[0066] B. Dissolve the solid mixture in a seventh solvent and dialyze it using a dialysis bag to obtain a second retention solution containing the functionalized carbon dots;

[0067] C. Dry the second retention solution to obtain the functionalized carbon dots;

[0068] Preferably, the molecular weight cutoff of the dialysis bag is 1000 Da;

[0069] Preferably, the second retention solution is dried under vacuum at 60°C for 20 hours;

[0070] Preferably, the seventh solvent is water.

[0071] The application of any one of the heteroatom-doped carbon dots prepared by the method of one of the present inventions, the heteroatom-doped carbon dots of the second of the present invention, the functionalized carbon dots of the third of the present invention, and the functionalized carbon dots prepared by the method of the fourth of the present invention in metal corrosion protection, particularly as corrosion inhibitors.

[0072] Definition of ionic liquid: A salt that is liquid at or near room temperature and is composed entirely of cations and anions, also known as a low-temperature molten salt.

[0073] The beneficial effects of this invention are:

[0074] To address the problem of unsatisfactory corrosion inhibition performance of current carbon dot corrosion inhibitors, this invention provides heteroatom-doped carbon dots, their preparation method, and functionalized carbon dots. The heteroatom-doped and functionalized carbon dots provided by this invention exhibit excellent corrosion inhibition performance: the corrosion inhibition efficiency of N-doped carbon dots at concentrations of 50 to 200 mg / L is above 24%, reaching 69.51% at a concentration of 50 mg / L; the corrosion inhibition efficiency of N and S-doped carbon dots at concentrations of 50 to 200 mg / L is above 47.47%, reaching 90.80% at a concentration of 50 mg / L; and the corrosion inhibition efficiency of functionalized carbon dots containing N-doped carbon dot structures at concentrations of 50 to 200 mg / L is also excellent. The corrosion inhibition rates are all above 96.5%. When the concentration of functionalized carbon dots containing N-atom doped carbon dot structures is 200 mg / L, the corrosion inhibition efficiency reaches 97.49%. The corrosion inhibition efficiency of functionalized carbon dots containing N and S-atom doped carbon dot structures with concentrations of 50 to 200 mg / L is all above 96.9%. When the concentration of functionalized carbon dots containing N and S-atom doped carbon dot structures is 150 mg / L, the corrosion inhibition efficiency reaches 97.07%. The functionalized carbon dots provided by this invention can achieve high corrosion inhibition and scale inhibition rates under high temperature and high salinity conditions in the Tarim Oilfield, and can be applied to the oil and gas development field of the Tarim Oilfield. Attached Figure Description

[0075] Figure 1 The infrared spectra of the functionalized carbon dots prepared using the N-atom doped carbon dots prepared in Example 1 in Example 6 and the infrared spectra of the functionalized carbon dots prepared using the N and S-atom doped carbon dots prepared in Example 4 in Example 9 are shown.

[0076] Figure 2 The polarization curves of the N80 carbon steel electrode in 1M hydrochloric acid containing different concentrations of functionalized carbon dots prepared in Example 6 are shown. The vertical axis represents the electrode potential, and the horizontal axis represents the logarithm of the current density.

[0077] Figure 3 The polarization curves of the N80 carbon steel electrode in 1M hydrochloric acid containing different concentrations of functionalized carbon dots prepared in Example 9 are shown. The vertical axis represents the electrode potential, and the horizontal axis represents the logarithm of the current density.

[0078] Figure 4 The polarization curves of the N80 carbon steel electrode in 1M hydrochloric acid containing different concentrations of N-atom-doped carbon dots prepared in Example 1 are shown. The vertical axis represents the electrode potential, and the horizontal axis represents the logarithm of the current density.

[0079] Figure 5 The polarization curves of the N80 carbon steel electrode in 1M hydrochloric acid containing N and S atom-doped carbon dots prepared in Example 4 at different concentrations are shown. The vertical axis represents the electrode potential, and the horizontal axis represents the logarithm of the current density.

[0080] Figure 6 Nyquist plots (with the real part of impedance as the x-axis and the imaginary part as the y-axis) of N80 carbon steel electrodes in 1M hydrochloric acid containing different concentrations of functionalized carbon dots prepared in Example 6.

[0081] Figure 7 Nyquist plot (with the real part of impedance as the x-axis and the imaginary part as the y-axis) of N80 carbon steel electrode in 1M hydrochloric acid containing different concentrations of functionalized carbon dots prepared in Example 9;

[0082] Figure 8 Bode plots (with the logarithm of frequency on the x-axis and the logarithm of impedance on the y-axis) of N80 carbon steel electrodes in 1M hydrochloric acid containing different concentrations of functionalized carbon dots prepared in Example 6.

[0083] Figure 9 Bode plots (with the logarithm of frequency on the x-axis and the logarithm of impedance on the y-axis) of N80 carbon steel electrodes in 1M hydrochloric acid containing different concentrations of functionalized carbon dots prepared in Example 9.

[0084] Figure 10 Nyquist plots (with the real part of the impedance as the x-axis and the imaginary part as the y-axis) are shown for N80 carbon steel electrodes in 1M hydrochloric acid containing different concentrations of N-atom-doped carbon dots prepared in Example 1.

[0085] Figure 11 Nyquist plot (with the real part of the impedance as the x-axis and the imaginary part as the y-axis) of N80 carbon steel electrode in 1M hydrochloric acid containing different concentrations of N and S atom-doped carbon dots prepared in Example 4.

[0086] Figure 12 Bode plots (with the logarithm of frequency on the x-axis and the logarithm of impedance on the y-axis) of N80 carbon steel electrodes in 1M hydrochloric acid containing N-atom-doped carbon dots prepared in Example 1 at different concentrations;

[0087] Figure 13 Bode plots (with the logarithm of frequency on the x-axis and the logarithm of impedance on the y-axis) of N80 carbon steel electrodes in 1M hydrochloric acid containing N and S atom-doped carbon dots prepared in Example 4 at different concentrations. Detailed Implementation

[0088] The present invention will be further described below with reference to the embodiments. However, the embodiments of the present invention are merely illustrative examples and should not be construed as limiting the present invention under any circumstances.

[0089] Preparation of heteroatom-doped carbon dots

[0090] Example 1

[0091] 1 g of ammonium citrate was added to a 50 ml beaker and heated in an oven at 180 °C for 2 h to obtain unpurified N-doped carbon dots. The unpurified N-doped carbon dots were dissolved in 30 ml of distilled water and centrifuged at 10000 r / min for 15 min. The supernatant containing the N-doped carbon dots was then dialyzed against distilled water for 12 h using a dialysis membrane with a molecular weight cutoff of 500 Da, with the distilled water changed every two hours. After dialysis, the retained solution containing the N-doped carbon dots was filtered through a PVDF membrane with a pore size of 0.22 μm to obtain solid N-doped carbon dots. Finally, the solid N-doped carbon dots were dried in a vacuum drying oven at 60 °C for 24 h to obtain purified N-doped carbon dots with a particle size of 7-8 nm and a median particle size of 7.35 nm, where the N-doping rate was 12.27 wt%.

[0092] Example 2

[0093] 1.2 g of ammonium citrate was added to a 50 ml beaker and heated in an oven at 200 °C for 2 h to obtain unpurified N-doped carbon dots. The unpurified N-doped carbon dots were dissolved in 30 ml of distilled water and centrifuged at 10000 r / min for 15 min. The supernatant containing the N-doped carbon dots was then dialyzed against distilled water for 12 h using a dialysis membrane with a molecular weight cutoff of 500 Da, with the distilled water changed every two hours. After dialysis, the retained solution containing the N-doped carbon dots was filtered through a PVDF membrane with a pore size of 0.22 μm to obtain solid N-doped carbon dots. Finally, the solid N-doped carbon dots were dried in a vacuum drying oven at 60 °C for 24 h to obtain purified N-doped carbon dots with a particle size of 7–8 nm and a median particle size of 7.42 nm, where the N-doping rate was 12.56 wt%.

[0094] Example 3

[0095] 0.8 g of ammonium citrate was added to a 50 ml beaker and heated in an oven at 190 °C for 2 h to obtain unpurified N-doped carbon dots. The unpurified N-doped carbon dots were dissolved in 30 ml of distilled water and centrifuged at 10000 r / min for 15 min. The supernatant containing the N-doped carbon dots was then dialyzed against distilled water for 12 h using a dialysis membrane with a molecular weight cutoff of 500 Da, with the distilled water changed every two hours. After dialysis, the retained solution containing the N-doped carbon dots was filtered through a PVDF membrane with a pore size of 0.22 μm to obtain solid N-doped carbon dots. Finally, the solid N-doped carbon dots were dried in a vacuum drying oven at 60 °C for 24 h to obtain purified N-doped carbon dots with a particle size of 7-8 nm and a median particle size of 7.66 nm, where the N-doping rate was 15.13 wt%.

[0096] Example 4

[0097] 0.6 g of citric acid and 1.2 g of thiourea were dissolved in 10 ml of water in a 50 ml beaker and reacted at 180 °C in an oven for 4 h to obtain unpurified N and S atom-doped carbon dots. The unpurified N and S atom-doped carbon dots were dissolved in 30 ml of distilled water and centrifuged at 10000 r / min for 15 min. The supernatant containing the N and S atom-doped carbon dots was then dialyzed against distilled water for 12 h using a dialysis membrane with a molecular weight cutoff of 500 Da, with the distilled water changed every two hours. After dialysis, the retained solution containing the N and S atom-doped carbon dots was filtered through a 0.22 μm PVDF membrane to obtain solid N and S atom-doped carbon dots. Finally, the obtained N and S atom-doped carbon dot solids were dried in a vacuum drying oven at 60°C for 24 hours to obtain purified N and S atom-doped carbon dots with a particle size of 7 to 8 nm and a median particle size of 7.82 nm. The N atom doping rate was 13.57% and the S atom doping rate was 0.21 wt%.

[0098] Preparation of aminoimidazolium-terminated ionic liquids

[0099] Example 5

[0100] 1 mol of 1-(3-aminopropyl)imidazole and 1 mol of 1-bromohexane were added to a single-necked round-bottom flask containing 10 ml of ethanol. The mixture was mechanically stirred at 800 r / min for 24 h at 90 °C, eventually producing an orange viscous melt, which was the crude product of the terminal aminoimidazole ionic liquid. The crude product of the terminal aminoimidazole ionic liquid was purified by organic solvent precipitation using a mixed solution of ethyl acetate and ethanol at a mass ratio of 1:2: the crude product was added to the mixed solution of ethyl acetate and ethanol, reacted, filtered, and the filtrate was collected. The ethyl acetate and ethanol in the filtrate were evaporated under vacuum at 60 °C to obtain the purified terminal aminoimidazole ionic liquid, namely 1-hexyl-3-aminopropyl-imidazole bromide, which was an orange viscous melt.

[0101] Preparation of functionalized carbon dots

[0102] Example 6

[0103] 1) Mix 2 mg of N-atom-doped carbon dots prepared in Example 1 with 1 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and dissolve in 100 mL of deionized water to obtain an N-atom-doped carbon dot solution;

[0104] 2) Dissolve 1g of the terminal aminoimidazolium ionic liquid prepared in Example 5 in 20mL of ethanol, and slowly add 0.5mL of triethylamine (0.364g) to obtain a terminal aminoimidazolium ionic liquid solution.

[0105] 3) Add the N-atom-doped carbon dot solution prepared in step 1) to the terminal aminoimidazolium ionic liquid solution prepared in step 2), and react at room temperature (25℃) with mechanical stirring at 800 r / min for 12 h to obtain crude functionalized carbon dots. Filter the mixture and collect the filter residue (which is a solid mixture containing functionalized carbon dots). Dialyze the filter residue in deionized water using a dialysis membrane with a molecular weight cutoff of 1000 Da for 6 h to obtain a retention solution containing functionalized carbon dots. Then, dry the retention solution containing functionalized doped carbon dots in a vacuum drying oven at 60℃ for 20 h to obtain purified functionalized carbon dots with a particle size of 7 to 8 mm and a median particle size of 7.38 nm.

[0106] Example 7

[0107] 1) Mix 2 mg of N-atom-doped carbon dots prepared in Example 2 with 1 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and dissolve in 100 mL of deionized water to obtain an N-atom-doped carbon dot solution;

[0108] 2) Dissolve 1g of the terminal aminoimidazolium ionic liquid prepared in Example 5 in 20mL of ethanol, and slowly add 0.5mL of triethylamine (0.364g) to obtain a terminal aminoimidazolium ionic liquid solution.

[0109] 3) Add the N-atom-doped carbon dot solution prepared in step 1) to the terminal aminoimidazolium ionic liquid solution prepared in step 2), and react at room temperature (25℃) with mechanical stirring at 800 r / min for 12 h to obtain crude functionalized carbon dots. Filter the mixture and collect the filter residue (which is a solid mixture containing functionalized carbon dots). Dialyze the filter residue in deionized water using a dialysis membrane with a molecular weight cutoff of 1000 Da for 6 h to obtain a retention solution containing functionalized carbon dots. Then, dry the retention solution containing functionalized doped carbon dots in a vacuum drying oven at 60℃ for 20 h to obtain purified functionalized carbon dots with a particle size of 7 to 8 mm and a median particle size of 7.46 nm.

[0110] Example 8

[0111] 1) Mix 2 mg of N-atom-doped carbon dots prepared in Example 3 with 1 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and dissolve in 100 mL of deionized water to obtain an N-atom-doped carbon dot solution;

[0112] 2) Dissolve 1g of the terminal aminoimidazolium ionic liquid prepared in Example 5 in 20mL of ethanol, and slowly add 0.5mL of triethylamine (0.364g) to obtain a terminal aminoimidazolium ionic liquid solution.

[0113] 3) Add the N-atom-doped carbon dot solution prepared in step 1) to the terminal aminoimidazolium ionic liquid solution prepared in step 2), and react at room temperature (25℃) with mechanical stirring at 800 r / min for 12 h to obtain crude functionalized carbon dots. Filter the mixture and collect the filter residue (which is a solid mixture containing functionalized carbon dots). Dialyze the filter residue in deionized water using a dialysis membrane with a molecular weight cutoff of 1000 Da for 6 h to obtain a retention solution containing functionalized carbon dots. Then, dry the retention solution containing functionalized doped carbon dots in a vacuum drying oven at 60℃ for 20 h to obtain purified functionalized carbon dots with a particle size of 7 to 8 mm and a median particle size of 7.70 nm.

[0114] Example 9

[0115] 1) Mix 2 mg of N and S atom-doped carbon dots prepared in Example 4 with 1 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and dissolve in 100 mL of deionized water to obtain an N and S atom-doped carbon dot solution.

[0116] 2) Dissolve 1g of the terminal aminoimidazolium ionic liquid prepared in Example 5 in 20mL of ethanol, and slowly add 0.5mL of triethylamine (0.364g) to obtain a terminal aminoimidazolium ionic liquid solution.

[0117] 3) Add the N and S atom-doped carbon dot solution prepared in step 1) to the terminal aminoimidazolium ionic liquid solution prepared in step 2), and react at room temperature (25℃) with mechanical stirring at 800 r / min for 12 h to obtain crude functionalized carbon dots. Filter the mixture and collect the filter residue (which is a solid mixture containing functionalized carbon dots). Dialyze the filter residue in deionized water using a dialysis membrane with a molecular weight cutoff of 1000 Da for 6 h to obtain a retention solution containing functionalized carbon dots. Then, dry the retention solution containing functionalized doped carbon dots in a vacuum drying oven at 60℃ for 20 h to obtain purified functionalized carbon dots with a particle size of 7 to 8 mm and a median particle size of 7.87 nm.

[0118] Experimental Evaluation

[0119] 1. Infrared spectroscopy determination of functionalized carbon dots

[0120] The infrared spectra of the functionalized carbon dots prepared in Examples 6 to 9 were determined using a Nicolet 6700 Fourier transform infrared spectrometer from Senno High-Tech (Beijing) International Experimental Technology Co., Ltd.

[0121] Figure 1 The upper half of the image shows the infrared spectrum of the functionalized carbon dots prepared using the N-atom-doped carbon dots prepared in Example 1, as described in Example 6, at 1184.7, 1307, 1400, 1615.7, 1643, 1717, 3000, and 3420 cm⁻¹. -1 There are obvious absorption peaks at each location, which are attributed to the absorption peaks of C-OH, CN, COO-, NH, C=N, C=O, CH and OH, respectively, proving that N atoms have been successfully doped; the lower half is the infrared spectrum of the functionalized carbon dots prepared by using N and S atom doped carbon dots prepared in Example 4 in Example 9, with peak values ​​of 1184.6, 1400, 1499.9, 1549.9, 1639.8, 1642.8, 2958.1 and 3412 cm⁻¹. -1 The series of characteristic peaks correspond to C-OH, COO-, NH, CN, NC=O, C=O, CH, and OH, respectively. Among these, the C-OH, COO-, C=O, and OH bonds are derived from two different carbon dots, while the NH and CN bonds are derived from imidazole ionic liquids. Furthermore, the formation of the NC=O bond indicates that the amino group of the imidazole reacted successfully with the carboxyl group of the carbon dot.

[0122] The infrared spectra of functionalized carbon dots prepared using N-doped carbon dots prepared in Examples 2 and 3 in Examples 7 and 8, respectively, are compared with those in Examples 8. Figure 1 The infrared spectra of the functionalized carbon dots prepared by N-atom doping in Example 6 are similar, all showing absorption peaks belonging to C-OH, CN, COO-, NH, C=N, C=O, CH and OH. This proves that the functionalized carbon dots prepared in Examples 7 and 8 have been successfully doped with N atoms.

[0123] 2. Determination of corrosion inhibition efficiency of heteroatom-doped carbon dots and functionalized carbon dots

[0124] The corrosion inhibition efficiency of heteroatom-doped carbon dots prepared in Examples 1 to 4 and functionalized carbon dots prepared in Examples 6 to 9 was determined by the weight loss method. The specific steps are as follows:

[0125] 1) Preparation of the corrosive solution:

[0126] i. Preparation of 1M hydrochloric acid: Mix 8.3 mL of 37.5 wt% hydrochloric acid with 100 mL of water until homogeneous to obtain 1M hydrochloric acid;

[0127] ii. Experimental group etching solution: Heteroatom-doped carbon dots or functionalized carbon dots were added to 1M hydrochloric acid to make the concentration of heteroatom-doped carbon dots or functionalized carbon dots in 1M hydrochloric acid 50mg / L, 100mg / L, 150mg / L and 200mg / L. Following the above method, heteroatom-doped carbon dots prepared in each of Examples 1 to 4 and functionalized carbon dots prepared in each of Examples 6 to 9 were prepared into etching solutions of the above different concentrations, for a total of 32 groups.

[0128] iii. Blank group etching solution: 1M hydrochloric acid was used as the etching solution;

[0129] 2) Take 33 N80 carbon steel sheets, remove the surface grease with degreasing cotton soaked in acetone, wipe them with degreasing cotton soaked in anhydrous ethanol, and after drying, measure their size and weigh them with an accuracy of 0.0001g.

[0130] 3) After adding the experimental group corrosion solution (32 groups in total) and the blank group corrosion solution prepared in step 1) to 500mL beakers respectively, hang an N80 carbon steel sheet treated in step 2) in each beaker.

[0131] 4) Seal the 33 beakers containing the corrosive solutions for the experimental and blank groups obtained in step 3) with plastic wrap and incubate at room temperature and pressure (specifically 25℃, 1.01×10⁻⁶). 5 After standing for 24 hours, remove the corroded N80 carbon steel sheet;

[0132] 5) Immerse the corroded N80 carbon steel sheet taken out in step 4) in pickling solution (obtained by dissolving 200g hexamethylenetetramine in 200mL of water, adding 70mL of concentrated hydrochloric acid, and finally diluting with water to 1000mL) for 3 to 5 minutes, then take it out and wipe the corroded N80 carbon steel sheet clean with degreased cotton soaked in anhydrous ethanol.

[0133] 6) Weigh the N80 carbon steel sheet that has been cleaned and corroded in step 5) using an electronic balance;

[0134] 7) The average corrosion rate of N80 carbon steel sheet and the corrosion inhibition efficiency of heteroatom-doped carbon dots and functionalized carbon dots are calculated by weight loss method. The formula for calculating the average corrosion rate is Equation (1); the formula for calculating the corrosion inhibition efficiency is Equation (2).

[0135]

[0136] In equation (1): r corr - Average corrosion rate, mm / a;

[0137] m - Mass of the N80 carbon steel sheet before the experiment, in g;

[0138] m t - The mass of the N80 carbon steel sheet after the experiment, in grams;

[0139] Total area of ​​S1-N80 carbon steel sheets;

[0140] The density of ρ-N80 carbon steel sheet, in g / cm³. 2 ;

[0141] t - experimental time, h.

[0142]

[0143] In equation (2), η1 is the corrosion inhibition rate;

[0144] Δm0 - Mass loss of N80 carbon steel sheet in the blank group, g;

[0145] Δm1 - Mass loss of N80 carbon steel sheet in the experimental group with heteroatom-doped or functionalized carbon dots, g. The average corrosion rate and corrosion inhibition efficiency were calculated using equations (1) and (2), and the specific results are shown in Table 1.

[0146] Table 1. Corrosion inhibition efficiency of heteroatom-doped carbon dots and functionalized carbon dots, and average corrosion rate of N80 carbon steel sheet

[0147]

[0148]

[0149] Table 1 shows that the N80 carbon steel sheet suffered the greatest mass loss in the blank group, indicating severe corrosion. The mass loss of the N80 carbon steel sheet was significantly reduced after the addition of heteroatom-doped carbon dots or functionalized carbon dots, indicating that both heteroatom-doped and functionalized carbon dots played a significant corrosion inhibition role. The data in Table 1 also show that the higher the concentration of heteroatom-doped carbon dots prepared in Examples 1 to 4 in the corrosive solution, the lower the corrosion inhibition efficiency. This may be because higher concentrations of heteroatom-doped carbon dots make them more prone to aggregation and precipitation in static corrosive solutions, resulting in a less dense corrosion inhibitor film on the N80 carbon steel sheet and thus lower corrosion inhibition efficiency. The corrosion inhibition efficiencies of the functionalized carbon dots prepared in Examples 6 to 9 at different concentrations were not significantly different, generally ranging from 96% to 98%, indicating better corrosion inhibition performance. Table 1 shows that the corrosion inhibition efficiency of N-doped carbon dots with concentrations ranging from 50 to 200 mg / L is above 24%, reaching 69.51% when the concentration is 50 mg / L. The corrosion inhibition efficiency of N and S-doped carbon dots with concentrations ranging from 50 to 200 mg / L is above 47.47%, reaching 90.80% when the concentration is 50 mg / L. The corrosion inhibition efficiency of N-doped carbon dots with concentrations ranging from 50 to 200 mg / L is also above 47.47%. The corrosion inhibition efficiency of functionalized carbon dots with N-doped carbon dot structures was above 96.5%. When the concentration of functionalized carbon dots with N-doped carbon dot structures was 200 mg / L, the corrosion inhibition efficiency reached 97.49%. The corrosion inhibition efficiency of functionalized carbon dots with N and S-doped carbon dot structures at concentrations of 50 to 200 mg / L was above 96.9%. When the concentration of functionalized carbon dots with N and S-doped carbon dot structures was 150 mg / L, the corrosion inhibition efficiency reached 97.07%. 2. Evaluation of the corrosion inhibition performance of heteroatom-doped carbon dots and functionalized carbon dots using electrochemical methods.

[0150] The corrosion inhibition performance of the N-doped carbon dots prepared in Example 1, the N and S-doped carbon dots prepared in Example 4, the functionalized carbon dots prepared using the N-doped carbon dots prepared in Example 6 from Example 1, and the functionalized carbon dots prepared using the N and S-doped carbon dots prepared in Example 9 from Example 4 were evaluated using electrochemical methods. The specific methods are as follows:

[0151] (1) Determination of corrosion parameters by polarization curve

[0152] a. Experimental apparatus: Gamry Referencr 600 electrochemical workstation; a three-electrode system using an N80 carbon steel electrode as the working electrode, a platinum electrode as the auxiliary electrode, and a silver-silver chloride electrode as the reference electrode;

[0153] b. Preparation of the corrosive solution:

[0154] To prepare 1M hydrochloric acid: Mix 8.3 mL of 37.5 wt% hydrochloric acid with 100 mL of water until homogeneous to obtain 1M hydrochloric acid;

[0155] The experimental group of corrosion solutions: heteroatom-doped carbon dots or functionalized carbon dots were added to 1M hydrochloric acid, so that the concentration of heteroatom-doped carbon dots or functionalized carbon dots in 1M hydrochloric acid was 50 mg / L, 100 mg / L, 150 mg / L and 200 mg / L.

[0156] Blank group etching solution: 1M hydrochloric acid was used as the etching solution;

[0157] c. Surface treatment of working electrode: Using an N80 carbon steel electrode as the working electrode, sand the surface of the N80 carbon steel working electrode with sandpaper and polish it, leaving a 1cm margin. 2 The remaining area is sealed with epoxy resin as the working area.

[0158] d. Immerse the surface-treated N80 carbon steel electrodes in the etching solutions of the experimental and blank groups, connect the three-electrode system, and begin the experiment. Use a Gamry Referencr 600 electrochemical workstation to measure the AC impedance of the etching solutions in both groups. In the potential dynamics study, a scan rate of 0.2 mV / s was selected to obtain the polarization curves. The intersection points of the cathode and anode polarization curves were determined, and the corrosion current density was calculated based on the intersection points. Corrosion current density values ​​(i) for all cases are given. corr ).

[0159]

[0160] In equation (3), i corr The corrosion current density is expressed in A / cm². 2 ;

[0161] I is the polarization current, in A;

[0162] S is the area of ​​the working electrode, in cm². 2 .

[0163]

[0164] In equation (4), r corr The corrosion rate is expressed in mm / a.

[0165] ρ is the density of the working electrode material, in g / cm³. 2 ;

[0166] i corr The corrosion current density is expressed in A / cm². 2 ;

[0167] F is the Faraday constant, 26.8 A·h / mol;

[0168] M is the molar mass of the electrode steel, in g / mol;

[0169] n is the number of electrons lost by the working electrode.

[0170]

[0171] In equation (5), IE represents the corrosion inhibition rate, in percentages (%).

[0172] The corrosion current density in the blank group is A / cm. 2 ;

[0173] i corr The corrosion current density after adding the corrosion inhibitor, in A / cm². 2 .

[0174] The corrosion rate and corrosion inhibition rate are obtained from equations (3), (4), and (5).

[0175] Following the above method, the corrosion inhibition performance of the heteroatom-doped carbon dots prepared in Examples 1 and 4, and the functionalized carbon dots prepared in Examples 6 and 9, was evaluated. The polarization curves of the N80 carbon steel electrode in 1M hydrochloric acid containing different concentrations of functionalized carbon dots and heteroatom-doped carbon dots were obtained as follows: Figures 2 to 5 ;according to Figure 2 , Figure 3 The polarization curves obtained from the polarization curves of N80 carbon steel electrodes in 1M hydrochloric acid containing different concentrations of functionalized carbon points are shown in Table 2.

[0176] Figure 2 The polarization curves of the N80 carbon steel electrode in 1M hydrochloric acid containing different concentrations of functionalized carbon dots prepared in Example 6 are shown. Figure 3 Polarization curves of N80 carbon steel electrodes in 1M hydrochloric acid containing different concentrations of functionalized carbon dots prepared in Example 9; E0 of the solution. corr The β value increased significantly, while the corrosion current decreased significantly, indicating a significant reduction in corrosion effectiveness. Compared to the control group experiment, the β value of the two corrosion inhibitors increased significantly. a and β c The values ​​all increased, indicating that both corrosion inhibitors suppressed both the anodic and cathodic reactions of corrosion.

[0177] Figure 4 The polarization curves of the N80 carbon steel electrode in 1M hydrochloric acid containing different concentrations of N-doped carbon dots prepared in Example 1 are shown. Figure 5 The polarization curves of the N80 carbon steel electrode in 1M hydrochloric acid containing different concentrations of N and S atom-doped carbon dots prepared in Example 4. β a and β cThe higher the β value, the stronger the corrosion inhibition effect of the corrosion inhibitor. Compared with the blank group experiment, the β value of the added corrosion inhibitor... c The values ​​both increased, indicating that the corrosion inhibitors mainly work by inhibiting the cathodic action of corrosion. Both corrosion inhibitors are cathodic type corrosion inhibitors.

[0178] Table 2. Polarization curves and corrosion parameters of N80 carbon steel electrodes in 1M hydrochloric acid containing different concentrations of functionalized carbon dots.

[0179]

[0180] As shown in Table 2, compared to the corrosion potential and corrosion current density of the blank group (i.e., 1M hydrochloric acid), the corrosion potential E of the experimental group's corrosion solution after adding functionalized carbon dots was significantly higher. corr The absolute value of increases significantly, while the corrosion current density i corr The corrosion inhibition efficiency of the functionalized carbon dots containing N-atom-doped carbon dot structures prepared in Example 6 was between 95.38% and 96.04%, while that of the functionalized carbon dots containing N and S-atom-doped carbon dot structures prepared in Example 9 was between 92.55% and 94.55%. Compared to the blank group corrosion solution, the Tafel slopes βa and βc values ​​of the experimental group corrosion solutions containing functionalized carbon dots containing N-atom-doped carbon dot structures prepared in Example 6 and those containing functionalized carbon dots containing N and S-atom-doped carbon dot structures prepared in Example 9 were both increased. This indicates that the functionalized carbon dots prepared in Examples 6 and 9 inhibited both the anodic and cathodic reactions of corrosion, especially the functionalized carbon dots prepared in Example 9, which significantly inhibited the cathodic reaction of corrosion.

[0181] (2) Electrochemical impedance spectroscopy measurement

[0182] A. Experimental apparatus: Gamry Referencr 600 electrochemical workstation; a three-electrode system using an N80 carbon steel electrode as the working electrode, a platinum electrode as the auxiliary electrode, and a silver-silver chloride electrode as the reference electrode;

[0183] B. Preparation of the corrosive solution:

[0184] To prepare 1M hydrochloric acid: Mix 8.3 mL of 37.5 wt% hydrochloric acid with 100 mL of water until homogeneous to obtain 1M hydrochloric acid;

[0185] The experimental group of corrosion solutions: heteroatom-doped carbon dots or functionalized carbon dots were added to 1M hydrochloric acid, so that the concentration of heteroatom-doped carbon dots or functionalized carbon dots in 1M hydrochloric acid was 50 mg / L, 100 mg / L, 150 mg / L and 200 mg / L.

[0186] Blank group etching solution: 1M hydrochloric acid was used as the etching solution;

[0187] C. Surface treatment of working electrode: Using an N80 carbon steel electrode as the working electrode, sand the surface of the N80 carbon steel working electrode with sandpaper and polish it, leaving a 1cm margin. 2 The remaining area is sealed with epoxy resin as the working area.

[0188] D. The surface-treated N80 carbon steel working electrode was immersed in the etching solutions of the experimental and blank groups. A three-electrode system was connected, and impedance measurements were performed at OCP (open circuit potential) using a Gamry Referencr 600 electrochemical workstation. An AC signal with a frequency range of 100 kHz to 0.01 Hz and an amplitude of 5 mVrms was used for the experiment to obtain impedance spectra, including Nyquist and Bode plots. The charge transfer resistance (Rt) under corrosion inhibition of heteroatom-doped or functionalized carbon dots was obtained from the Nyquist plot. ct ) value and charge transfer resistance of blank group The corrosion inhibition efficiency can be calculated using the following formula:

[0189]

[0190] In equation (6), η is the corrosion inhibition efficiency;

[0191] R ct The charge transfer resistance after adding heteroatom-doped or functionalized carbon dots;

[0192] The charge transfer resistance is for carbon dots without heteroatom doping or functionalized carbon dots.

[0193] The corrosion inhibition efficiency can be calculated using formula (6).

[0194] Following the above method, the corrosion inhibition performance of the functionalized carbon dots prepared in Examples 6 and 9, and the heteroatom-doped carbon dots prepared in Examples 1 and 4, was evaluated. Impedance spectra (including Nyquist and Bode plots) of the N80 carbon steel electrode in 1M hydrochloric acid containing different concentrations of functionalized or heteroatom-doped carbon dots were obtained. Figures 6 to 13 ;Depend on Figure 6 , Figure 7 The Nyquist plots show the electrochemical impedance spectral parameters of the N80 carbon steel electrode in 1M hydrochloric acid containing different concentrations of functionalized carbon dots, as detailed in Table 3.

[0195] Figure 6 , Figure 8 The images show the Nyquist and Bode plots of an N80 carbon steel electrode in 1M hydrochloric acid containing different concentrations of functionalized carbon dots prepared in Example 6, respectively. Figure 7 , Figure 9The Nyquist and Bode plots are for an N80 carbon steel electrode in 1M hydrochloric acid containing different concentrations of functionalized carbon dots prepared in Example 9, respectively. It can be seen that the impedance modulus increases with the increase of the concentration of functionalized carbon dots, and the impedance reaches a maximum value at lower frequencies, indicating that the functionalized carbon dot molecules form a corrosion inhibitor film on the metal surface, thereby inhibiting the corrosion process.

[0196] Figure 10 , Figure 12 The images show the Nyquist and Bode plots of an N80 carbon steel electrode in 1M hydrochloric acid containing different concentrations of N-doped carbon dots prepared in Example 1. Figure 11 , Figure 13 The figures show the Nyquist and Bode plots of an N80 carbon steel electrode in 1M hydrochloric acid containing different concentrations of N and S atom-doped carbon dots prepared in Example 4. After adding the N atom-doped carbon dots prepared in Example 1, the diameter of the impedance arc gradually increased, but the increase was not significant, reaching its maximum at an addition amount of 150 mg / L. Furthermore, the order of impedance arc size was 50 mg / L < 100 mg / L < 200 mg / L < 150 mg / L. After adding the N and S atom-doped carbon dots prepared in Example 4, the impedance arc increased significantly. When the addition amount of N and S atom-doped carbon dots prepared in Example 4 was 50 mg / L, the corrosion inhibition effect was significantly increased. Furthermore, the order of impedance arc size was 200 mg / L < 150 mg / L < 100 mg / L < 50 mg / L.

[0197] Combination Figures 6 to 13 Analysis shows that, in systems with the same addition concentration, the two functionalized carbon dots have a higher degree of adsorption capacity and a larger coverage area compared with the two heteroatom-doped carbon dots, thus achieving a better corrosion inhibition effect.

[0198] Table 3. Electrochemical impedance spectroscopy parameters of N80 carbon steel sheets in corrosive solutions containing different concentrations of functionalized carbon dots.

[0199]

[0200] As shown in Table 3, the solution resistance Rs of N80 carbon steel sheets in 1M hydrochloric acid containing different concentrations of functionalized carbon dots is similar. With increasing concentration of functionalized carbon dots, the film impedance R... f The gradual increase indicates the presence of a corrosion inhibitor adsorption film. Simultaneously, with the increase of functionalized carbon dot content, the charge transfer resistance R... ct The trend is upward. This is because corrosion inhibitor molecules with low dielectric constants can replace water molecules with high dielectric constants, thereby reducing the exposed area of ​​the N80 carbon steel sheet in the corrosive solution. The above data also demonstrate that the functionalized carbon dots prepared in Examples 6 and 9 have good corrosion inhibition performance.

[0201] While the present invention has been described with reference to specific embodiments, those skilled in the art will understand that various changes can be made without departing from the true spirit and scope of the invention. Furthermore, numerous modifications can be made to the subject, spirit, and scope of the invention to suit specific situations, materials, material compositions, and methods. All such modifications are included within the scope of the claims of the present invention.

Claims

1. A functionalized carbon dot comprising a heteroatom-doped carbon dot and an ionic liquid, wherein the ionic liquid is grafted onto the heteroatom-doped carbon dot; in, The heteroatom-doped carbon dots are prepared according to the following steps: The carbon-heteroatom source is heated, or a mixture of carbon source and heteroatom source is heated to carry out the first reaction, followed by purification, to obtain the heteroatom-doped carbon dots; In the heteroatom-doped carbon dots, the heteroatoms are N atoms and / or S atoms; the carbon-heteroatom source is a carbon-nitrogen atom source; the carbon source is citric acid; the heteroatom source is a nitrogen-sulfur source; the carbon-nitrogen atom source is ammonium citrate; the nitrogen-sulfur source is thiourea; the doping rate of the N atoms is 12.27 wt% to 15.13 wt%; and / or the doping rate of the S atoms is 0.13 wt% to 0.21 wt%. The ionic liquid is 1-hexyl-3-aminopropyl-imidazolium bromide.

2. The functionalized carbon dots according to claim 1, characterized in that, The mass ratio of the heteroatom-doped carbon dots to the ionic liquid is 0.002:

1.

3. The functionalized carbon dots according to claim 1 or 2, characterized in that, The mass ratio of the carbon source to the heteroatom source is 1:

2.

4. The functionalized carbon dots according to claim 1 or 2, characterized in that, The carbon source and heteroatom source are dissolved in a first solvent, mixed, and then heated to carry out the first reaction; The conditions for the first reaction are to react at 180°C to 200°C for 2 to 4 hours; The first solvent is water.

5. The functionalized carbon dots according to claim 1 or 2, characterized in that, The product obtained from the first reaction was purified according to the following steps: 1) Disperse the product obtained from the first reaction in a second solvent, centrifuge, and obtain a supernatant containing the heteroatom-doped carbon dots; 2) Dialyze the supernatant using a dialysis bag to obtain a first retention solution containing the heteroatom-doped carbon dots; 3) Filter the first retention solution to obtain heteroatom-doped carbon dot solids; 4) The heteroatom-doped carbon dot solid is dried to obtain the heteroatom-doped carbon dot; The molecular weight cutoff of the dialysis bag is 500 Da; The filtration was performed using a PVDF membrane with a pore size of 0.22 μm; The drying conditions for the heteroatom-doped carbon dot solid were vacuum drying at 60°C for 24 hours; The second solvent is water.

6. The functionalized carbon dots according to claim 1 or 2, characterized in that, The particle size of the heteroatom-doped carbon dots is 7 nm to 8 nm.

7. The functionalized carbon dots according to claim 1 or 2, characterized in that, The particle size of the functionalized carbon dots is 7 nm to 8 nm.

8. A method for preparing functionalized carbon dots as described in any one of claims 1 to 7, comprising the following steps: (1) Mix the heteroatom-doped carbon dots with a third solvent to obtain a heteroatom-doped carbon dot solution; (2) The ionic liquid and the fourth solvent are mixed to obtain an ionic liquid solution; (3) Mix the heteroatom-doped carbon dot solution and the ionic liquid solution to carry out a second reaction to obtain the crude product of the functionalized carbon dots; (4) The crude product of the functionalized carbon dots is purified to obtain the functionalized carbon dots.

9. The method according to claim 8, characterized in that, The mass ratio of the heteroatom-doped carbon dots to the ionic liquid is 0.002:1; The third solvent is water; and / or the fourth solvent is ethanol; The conditions for the second reaction were stirring for 12 hours.

10. The method according to claim 8, characterized in that, The heteroatom-doped carbon dots, the catalyst, and the third solvent are mixed to obtain the heteroatom-doped carbon dot solution; and / or The ionic liquid, triethylamine, and a fourth solvent are mixed to obtain the ionic liquid solution; The mass ratio of the catalyst to heteroatom-doped carbon dots is 500:1; and / or The mass ratio of triethylamine to the ionic liquid is 0.364:1; The catalyst is 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride.

11. The method according to claim 8, characterized in that, The ionic liquid is prepared by the following method: 1-(3-aminopropyl)imidazolium and 1-bromohexane were mixed and subjected to a third reaction, followed by purification to obtain the ionic liquid. The molar ratio of 1-(3-aminopropyl)imidazolium to 1-bromohexane is 1:1; The 1-(3-aminopropyl)imidazolium and 1-bromohexane are mixed in a fifth solvent; and / or The fifth solvent is ethanol; The conditions for the third reaction are stirring at 90°C for 24 hours; The product obtained from the third reaction was purified in the following manner: a. Mix the product obtained from the third reaction with the sixth solvent, carry out the fourth reaction, filter, and obtain a filtrate containing the ionic liquid; b. Evaporate the filtrate to obtain the ionic liquid; The sixth solvent is a mixture of ethyl acetate and ethanol; and / or The mass ratio of ethyl acetate to ethanol is (1 to 2):(1 to 2); The evaporation is vacuum evaporation; and / or the evaporation temperature is 60°C.

12. The method according to claim 8, characterized in that, In step (4), the crude product of the functionalized carbon dots is purified in the following manner: A. The crude product containing the functionalized carbon dots is filtered to obtain a solid mixture containing the functionalized carbon dots; B. Dissolve the solid mixture in a seventh solvent and dialyze it using a dialysis bag to obtain a second retention solution containing the functionalized carbon dots; C. Dry the second retention solution to obtain the functionalized carbon dots; The molecular weight cutoff of the dialysis bag is 1000 Da; The second retention solution was dried under vacuum at 60°C for 20 hours. The seventh solvent is water.

13. The application of any one of the functionalized carbon dots according to any one of claims 1 to 7 and the functionalized carbon dots prepared by the method according to any one of claims 8 to 12 in metal corrosion protection.

14. The application according to claim 13, characterized in that, The application refers to the use of the functionalized carbon dots as corrosion inhibitors.

Images