An indium oxide microtube modified carbon fiber photosensitive electrode, its preparation method and application

Abstract

The present invention discloses an indium oxide microtube modified carbon fiber photosensitive electrode, its preparation method and application, which includes a carbon fiber substrate electrode and indium oxide microtubes fixed on the surface of the carbon fiber electrode. The indium oxide microtubes have a hollow tubular structure, and the photosensitive electrode constructed by fixing them on the surface of the carbon fiber substrate has high photoelectric conversion performance and can effectively promote surface adsorption and catalysis. The present invention uses the above indium oxide microtube modified carbon fiber photosensitive electrode assembled with glucose dehydrogenase on the surface as a working electrode, and constructs a photoelectrochemical sensing platform for glucose detection by combining an enzyme-catalyzed cycle amplification strategy. Compared with directly using glucose as an electron donor, the catalytic cycle induced by nicotinamide adenine dinucleotide coenzyme increases the photocurrent signal of the working electrode by about 5 times, and there is a significant improvement in detection sensitivity.

Description

Technical Field

[0001] The invention belongs to the field of photoelectric sensing materials, and particularly relates to an indium oxide microtube modified carbon fiber photosensitive electrode and a preparation method and application thereof. Background Art

[0002] Glucose is a very important biological substance. The development of highly sensitive glucose content detection technology plays a vital role in the early diagnosis and treatment of diseases. At present, there are many methods for glucose detection, but they often have shortcomings such as slow analysis speed or high cost. As an analytical technology that has developed rapidly based on the combination of photoelectrochemical (PEC) process and electrochemical biosensor, PEC sensing mainly detects the content of the analyte through the change of electrical signals caused by the specific interaction between target molecules and recognition elements under light radiation. Due to the use of different excitation and detection methods, PEC sensing has lower background signals and higher sensitivity compared with traditional electrochemical analysis technology, so it is gradually developing into a highly promising biosensor technology. However, in order to meet the increasing detection needs, the development of new optoelectronic materials and the design of highly sensitive sensing strategies are still two major problems that need to be solved in the development of PEC biosensor technology.

[0003] Metal oxide nanomaterials have shown extensive application potential in PEC biosensing due to their unique physical and chemical properties. However, due to the limitation of the separation and transfer speed of electron-hole pairs, the photoelectric conversion efficiency of this type of material needs to be further improved. Hollow nanomaterials have significantly reduced surface diffusion length, which is conducive to accelerating the separation of electron-hole pairs; at the same time, the multi-light scattering / reflection effect generated by the internal gaps can enhance the material's ability to absorb light; in addition, the rich active sites provided by their large specific surface area are not only conducive to the loading of guest substances, but also increase the contact area between the material and the electrolyte solution, accelerating the interfacial charge transfer and reaction rate.

[0004] In situ generation of electron donors is a commonly used PEC biosensing strategy. How to further amplify the signal based on this strategy is another effective way to improve the sensitivity of biological detection. Summary of the invention

[0005] Purpose of the invention: The technical problem to be solved by the present invention is to provide an indium oxide microtube modified carbon fiber photosensitive electrode with a hollow tubular structure in view of the shortcomings of the prior art, so as to enrich the types of photosensitive electrodes that can be used for PEC sensing and broaden ideas for the development of PEC biosensor technology.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] Indium oxide microtube modified carbon fiber2 O 3 MTs / CF) photosensitive electrode, comprising a carbon fiber (CF) electrode and an indium oxide microtube (InO2) fixed on the surface of the carbon fiber electrode. 2 O 3 MTs), the indium oxide microtubes have a hollow tubular structure, and the indium oxide microtubes (In 2 O 3 MTs) materials can increase the specific surface area of ​​the constructed electrode, increase the loading capacity of the "guest", and accelerate the interface reaction and charge transfer speed.

[0008] Specifically, the indium oxide microtubes are fixed on the surface of the carbon fiber electrode by a heat treatment method.

[0009] Furthermore, the present invention also provides the above-mentioned indium oxide microtube modified carbon fiber (In 2 O 3 The preparation method of MTs / CF) photosensitive electrode comprises the following steps:

[0010] (1) reacting terephthalic acid and hydrated indium nitrate in an organic solvent, and subjecting the reaction product to solid-liquid separation, washing, and drying to obtain an In-MIL-68 intermediate having a solid hexagonal prism morphology;

[0011] (2) calcining the In-MIL-68 intermediate of step (1) to obtain indium oxide microtubes (In 2 O 3 MTs);

[0012] (3) Dispersing the indium oxide microtube material obtained in step (2) in water, then dropping the dispersion on the surface of the carbon fiber electrode, drying with an infrared lamp and calcining to obtain the obtained product.

[0013] Specifically, in step (1), the organic solvent is N,N-dimethylformamide; the concentration of terephthalic acid in the organic solvent is 1 mg / mL to 2 mg / mL (preferably 1.5 mg / mL); the concentration of hydrated indium nitrate in the organic solvent is 1 mg / mL to 2 mg / mL (preferably 1.5 mg / mL); the reaction temperature is 110° C. to 130° C. (preferably 120° C.), and the reaction time is 20 min to 40 min (preferably 30 min); and the washing is repeated 2 to 3 times with anhydrous ethanol.

[0014] Specifically, in step (2), the calcination conditions are as follows: heating to 110°C to 130°C (preferably 120°C) at a heating rate of 4°C / min to 7°C / min (preferably 5°C / min), calcining for 40 min to 90 min, and then heating to 450°C to 550°C (preferably 500°C) at a heating rate of 4°C / min to 6°C / min (preferably 5°C / min) and calcining for 1.5 h to 2.5 h (preferably 2 h).

[0015] Specifically, in step (3), the indium oxide microtubes are dispersed in water at a mass-volume ratio of 2 mg / mL to 10 mg / mL (preferably 8 mg / mL), and the dispersion method is ultrasonic dispersion; the dispersion liquid is dropped onto the surface of the carbon fiber electrode at a dosage of 1 μL / mm 2 ~1.5 μL / mm 2 of the carbon fiber electrode surface.

[0016] Specifically, in step (3), the calcination conditions are as follows: heating to 250°C to 350°C (preferably 300°C) at a heating rate of 4°C / min to 6°C / min (preferably 5°C / min) and holding for 40 min to 80 min.

[0017] Furthermore, the present invention also claims the application of the above indium oxide microtube modified carbon fiber photosensitive electrode in constructing a photoelectrochemical (PEC) sensor.

[0018] Even further, the photoelectrochemical (PEC) sensor constructed by the indium oxide microtube modified carbon fiber photosensitive electrode of the present invention is preferably used for detecting glucose.

[0019] Specifically, the method for the photoelectrochemical (PEC) sensor constructed by the indium oxide microtube modified carbon fiber photosensitive electrode of the present invention to detect glucose is as follows: using the electrostatic assembly technology to assemble glucose dehydrogenase (GDH) on the above indium oxide microtube modified carbon fiber photosensitive electrode, and using it as a working electrode to form a three-electrode system with a counter electrode and a reference electrode, and placing them together in a glucose solution to be measured containing coenzyme, and detecting the concentration of glucose by measuring the change in the photocurrent intensity of the system under light excitation;

[0020] The coenzyme includes but is not limited to nicotinamide adenine dinucleotide (NAD), the counter electrode can be a platinum wire electrode; the reference electrode can be an Ag / AgCl electrode.

[0021] Beneficial effects:

[0022] (1) The indium oxide microtubes (In 2 O 3(MTs) have a hollow tubular structure, and a photosensitive electrode was prepared by modifying it on the surface of carbon fiber (CF). Using L-cysteine as an electron donor, the photocurrent intensity generated by the photosensitive electrode did not change significantly when the excitation light source was continuously turned on and off within 300 seconds, indicating that the electrode has good photoelectric conversion stability.

[0023] (2) The present invention combines a catalytic cycle amplification strategy to construct a PEC sensing method for glucose. By using an electrostatic assembly technique, glucose dehydrogenase (GDH) was assembled layer by layer on the above-mentioned indium oxide microtube-modified carbon fiber photosensitive electrode to obtain a GDH / In 2 O 3 MTs / CF electrode. Compared with directly using glucose as an electron donor, the catalytic cycle induced by the nicotinamide adenine dinucleotide (NAD) coenzyme increased the photocurrent signal of the GDH / In 2 O 3 MTs / CF electrode by nearly 5 times, showing a significant improvement in detection sensitivity.

[0024] (3) The glucose PEC sensor of the present invention has good selectivity for glucose, and its response value to glucose is equivalent to that of 5-fold concentration of glutamic acid, 10-fold concentration of glutathione, or ascorbic acid; within the concentration range of 0.1 mM - 10 mM, the photocurrent signal intensity of the sensor shows a good linear relationship with the logarithm of the glucose concentration, and the linear correlation coefficient is 0.9815. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The following further describes the present invention in detail with reference to the drawings and specific embodiments, and the above and / or other advantages of the present invention will become clearer.

[0026] Figure 1 are the scanning electron microscope images of In-MIL-68 hexagonal prisms (a - b) and the scanning electron microscope images of In 2 O 3 MTs (c - d).

[0027] Figure 2 is the X-ray photoelectron spectroscopy of In 2 O 3 MTs.

[0028] Figure 3 is the ultraviolet-visible diffuse reflectance spectrum (a) and X-ray diffraction spectrum (b) of In 2 O 3 MTs.

[0029] Figure 4 is the optimization of the amount of In 2 O 3 used and the corresponding In 2 O3 Stability of photocurrent of MTs / CF photosensitive electrode.

[0030] Figure 5 is GDH / In 2 O 3 Fabrication process of MTs / CF composite electrode (a) and schematic diagram of glucose PEC sensing principle based on in-situ generated electron donor recycling strategy (b).

[0031] Figure 6 is the photocurrent response curve during the construction of glucose PEC sensor. Among them, curves (a) and (b) are respectively the photocurrent response curves of In 2 O 3 MTs / CF electrode to PBS solution before and after adding glucose; (c) and (d) are respectively the photocurrent response curves of GDH / In 2 O 3 MTs / CF electrode to glucose solution before and after adding coenzyme NAD.

[0032] Figure 7 is the selectivity of glucose PEC sensor: (a) photocurrent response curve; (b) bar chart of photocurrent increment (relative to 0.01M PBS solution). Specific implementation mode

[0033] According to the following embodiments, the present invention can be better understood.

[0034] Example 1: Preparation of In 2 O 3 MTs / CF composite electrode

[0035] Weigh 40 mg each of terephthalic acid and indium nitrate hydrate into a 100 mL round-bottom flask, then add 40 mL of N,N-dimethylformamide (DMF). After stirring with a magnetic stirrer until the solids are completely dissolved, place the round-bottom flask in an oil bath at 110 °C and react with stirring. After 20 min, stop heating and continue stirring until the solution in the flask cools to room temperature to obtain the In-MIL-68 intermediate. Transfer the product In-MIL-68 intermediate of Example 1 to a 50 mL centrifuge tube, centrifuge at 11000 r / min for 10 min to separate the solid and liquid. Wash the precipitate by adding 20 mL of absolute ethanol to the separated product, mixing it with a vortex mixer and then centrifuging and separating it in the same way, and repeat washing the precipitate three times. Finally, dry the washed solid and transfer it to a porcelain boat. First, heat it in a muffle furnace or tube furnace at a heating rate of 4 °C / min to 110 °C and calcine for 40 min, then heat it at a heating rate of 4 °C / min to 450 °C and calcine for 1.5 h, and cool it to room temperature to obtain In 2 O 3MTs materials.

[0036] Weigh the In synthesized in Example 1 2 O 3 MTs materials and disperse them in water (concentration: 6 mg / mL), and ultrasonicate for 5 min in an ultrasonic cleaner to ensure uniform dispersion. Stick a transparent tape with a 5-mm-diameter round hole on the surface of a 30-mm × 7-mm carbon fiber electrode to fix the working area. Pipette 20 μL of the In 2 O 3 MTs dispersion and drop it into the round hole on the electrode surface, and then place the electrode under an infrared lamp for drying. After the electrode is dried, remove the transparent tape on the electrode surface, place the electrode in a muffle furnace or a tube furnace, heat it up to 250 °C at a rate of 4 °C / min, and hold for 40 min to enhance the adhesion of In 2 O 3 on the surface of the carbon fiber substrate and enhance the hydrophilicity of the carbon paper. After calcination, stick the transparent tape with a 5-mm-diameter round hole again to re-fix the working area, and finally obtain the In 2 O 3 MTs / CF composite electrode.

[0037] Example 2: Preparation of In 2 O 3 MTs / CF composite electrode

[0038] Weigh 80 mg each of terephthalic acid and indium nitrate hydrate in a 100-mL round-bottom flask, add 40 mL of DMF, stir with a magnetic stirrer until the solids are completely dissolved, then place the round-bottom flask in an oil bath at 130 °C and react with stirring. After 40 min, stop heating and continue stirring until the solution in the flask cools to room temperature to obtain the In-MIL-68 intermediate. After performing the same washing and drying operations as in Example 1 on the product In-MIL-68 in Example 2, transfer it to a porcelain boat, first heat it up to 130 °C at a heating rate of 7 °C / min in a muffle furnace or a tube furnace, calcine for 90 min, then heat it up to 550 °C at a heating rate of 6 °C / min, calcine for 2.5 h, and cool to room temperature to obtain In 2 O 3 MTs materials.

[0039] Weigh the In synthesized in Example 2 2 O 3 MTs materials and disperse them in water (concentration: 10 mg / mL), and ultrasonicate for 5 min in an ultrasonic cleaner to ensure uniform dispersion. Pipette 20 μL of the prepared In 2 O 3The MTs dispersion was dropped into the round holes on the surface of the carbon fiber electrode with the same specifications as in Example 1 and the same working area fixed, and then the electrode was dried under an infrared lamp. After the electrode was dried, the transparent tape on the electrode surface was removed, and the electrode was placed in a muffle furnace or a tube furnace and heated to 350 °C at a rate of 6 °C / min and held for 80 min. After calcination, the working area was fixed again by the same method as in Example 1, and finally In 2 O 3 MTs / CF composite electrode was obtained.

[0040] Example 3: Preparation of In 2 O 3 MTs / CF electrode

[0041] 60 mg of terephthalic acid and indium nitrate hydrate were weighed into a 100 mL round-bottom flask, and then 40 mL of DMF was added. After stirring with a magnetic stirrer until the solid was completely dissolved, the round-bottom flask was placed in an oil bath at 120 °C and reacted with stirring. After 30 min, heating was stopped and stirring was continued until the solution in the flask cooled to room temperature to obtain the In-MIL-68 intermediate. After the product In-MIL-68 in Example 3 was washed and dried in the same manner as in Example 1, it was transferred to a porcelain boat. First, it was heated to 120 °C at a heating rate of 5 °C / min in a muffle furnace or a tube furnace and calcined for 1 h, then heated to 500 °C at a heating rate of 5 °C / min and calcined for 2 h, and cooled to room temperature to obtain In 2 O 3 MTs material.

[0042] To determine the morphologies of the In-MIL-68 intermediate and In 2 O 3 MTs material synthesized in Example 3, we took the scanning electron microscope images of these two materials, as Figure 1 shown. As Figure 1 (a) shows, In-MIL-68 has a columnar structure with a column length of about 4 μm; Figure 1 (b) further shows that In-MIL-68 has a solid hexagonal prism morphology with a hexagonal cross-section and a column diameter of about 1 μm. After calcination, as Figure 1 (c) shows, the synthesized indium oxide microtubes (In 2 O 3 MTs) exhibit a hollow tubular structure. Compared with In-MIL-68, the tube length has no obvious change and is still about 4 μm; Figure 1 (d) The high-resolution image shown further shows that the synthesized material has a hollow structure with a hexagonal cross-section and a tube diameter of about 1 μm. In addition, it can also be seen that the synthesized In 2 O 3The MTs material is composed of nanoparticle accumulation, which makes the tube wall porous.

[0043] Figure 2 It is the In synthesized in Example 3 2 O 3 X-ray photoelectron spectroscopy characterization of the MTs material. From Figure 2 The full spectrum of (a) shows that, except for the strong characteristic peaks of In and O elements at their corresponding binding energies, no characteristic peaks of other irrelevant elements are observed, indicating that there are no other obvious interfering substances in the synthesized material. Figure 2 The high-resolution spectrum of (b) shows spectral peaks at binding energies of 444.4 eV and 452 eV, corresponding to the characteristic peaks of In 3d 5 / 2 and In 3d 3 / 2 , which indicates the existence of In 3+ . Figure 2 The two characteristic peaks of oxygen in the high-resolution spectrum of (c) at 529.9 eV and 531.9 eV are attributed to In-O-In and oxygen defects in metal oxides, respectively. The above results comprehensively show that the chemical states of the elements in the synthesized material are In 3+ and O 2- .

[0044] To determine the light absorption performance of the In 2 O 3 MTs material, the present invention measured the ultraviolet-visible diffuse reflection spectrum of the material synthesized in Example 3, and the results are as Figure 3 shown. From Figure 3 (a), it can be seen that the material has a large absorption in the wavelength range of 300 - 450 nm, while the absorption is small in the wavelength range of 450 nm and above. Therefore, 410 nm is selected as the excitation light source to test the optoelectronic properties of the material. In addition, the present invention also performed X-ray powder diffraction characterization on the In 2 O 3 MTs material, and the results are as Figure 3 (b) shown. Comparing the X-ray powder diffraction spectrum with the PDF card, the positions and intensities of the peaks in this spectrum are consistent with the PDF card numbered 06-0416, further confirming that the synthesized material is In 2 O 3 .

[0045] Weigh the In 2 O 3 MTs material synthesized in Example 3, disperse it in water (concentrations are 2 mg / mL, 4 mg / mL, 6 mg / mL, 8 mg / mL, 10 mg / mL), and ultrasonicate for 5 min in an ultrasonic cleaner to ensure uniform dispersion. Respectively pipette 20 μL of the prepared In with different concentrations2 O 3 The MTs dispersion was dropped into the round holes on the surface of the carbon fiber electrode with the same specifications as in Example 1 and the same working area fixed, and then the electrode was dried under an infrared lamp. After the electrode was dried, the transparent tape on the electrode surface was removed, and the electrode was placed in a muffle furnace or a tube furnace and heated to 300 °C at a rate of 5 °C / min and maintained for 1 h to enhance the adhesion of In 2 O 3 on the carbon fiber substrate surface and enhance the hydrophilicity of the carbon paper. After calcination, a transparent tape with a round hole of 5 mm in diameter was pasted again to re-fix the working area, and finally an In 2 O 3 MTs / CF composite electrode was obtained.

[0046] Under light excitation, In 2 O 3 MTs will generate electron-hole pairs. When there is an electron donor in the solution, the recombination of carriers can be effectively inhibited and a stable photocurrent signal can be generated. Therefore, the amount of In 2 O 3 MTs fixed on the carbon fiber electrode must have a significant impact on the optoelectronic performance of the electrode. As Figure 4 (a) shows, when the amount of In 2 O 3 MTs used is low, with the increase of its amount, the photocurrent of the electrode shows a gradually increasing trend, which is due to the fact that the more the amount of In 2 O 3 MTs used, the more electron-hole pairs generated by excitation; but when the amount of In 2 O 3 MTs used exceeds 8 mg / mL, the contact area between In 2 O 3 MTs and the solution will no longer increase, and the thickened In 2 O 3 MTs layer will inhibit the electron transfer process between it and the carbon fiber to a certain extent. At this time, the photocurrent will show a downward trend with the increase of the amount of In 2 O 3 . Therefore, the present invention determines 8 mg / mL as the optimal amount of In 2 O 3 Mts / CF photosensitive electrode required for In 2 O 3 MTs. For the In 2 O 3 prepared with the optimized amount of In 2 O 3 MTs / CF electrode was subjected to a stability test, and the results are asFigure 4 (as shown in (b). From Figure 4 it can be seen that, using L-cysteine as the electron donor, the light source is continuously turned on and off within 300 s, and the photocurrent intensity of the In 2 O 3 MTs / CF electrode remains basically unchanged, indicating that the constructed optoelectronic functional interface has good stability.

[0047] Example 4: Construction of a glucose PEC sensing strategy

[0048] The present invention utilizes the electrostatic assembly technology to achieve the modification of glucose dehydrogenase (GDH) on the surface of the In 2 O 3 MTs / CF electrode. The construction process is shown in Figure 5 . As Figure 5 (a) shows, first, the immobilization of In 2 O 3 MTs on the surface of CF is achieved by the heat treatment method; subsequently, based on the electrostatic assembly technology of poly(diallyldimethylammonium chloride) (PDDA), the modification of GDH on the surface of the In 2 O 3 MTs / CF electrode is realized, and then the GDH / In 2 O 3 MTs / CF composite electrode is constructed. When the composite electrode is placed in a glucose solution containing nicotinamide adenine dinucleotide (NAD), based on the fact that GDH catalyzes the oxidation of glucose to produce the electron donor NADH in the presence of the coenzyme NAD, the photocurrent signal can be enhanced. Moreover, while NADH provides electrons to the GDH / In 2 O 3 MTs / CF composite electrode, it will also generate the oxidized coenzyme NAD, thereby promoting cyclic catalysis and realizing the further amplification of the signal. Recording the change of the photocurrent intensity during the process can achieve signal-enhanced PEC sensing of glucose, Figure 5 (b) is a schematic diagram of the process sensing principle.

[0049] The specific process is as follows: 10 μL of 2% PDDA solution is dropped onto the working area of the best In 2 O 3 MTs / CF electrode prepared in Example 3. After standing for 30 min, the electrode is cleaned with 0.01 M PBS solution, and then 10 μL of 2.4 mg / mL GDH solution is dropped onto the working area of the electrode. After standing for 30 min, the electrode is cleaned again with 0.01 M PBS solution to complete the assembly of one layer of GDH on the electrode surface. Repeat the above steps, and the GDH / In 2 O 3 MTs / CFs electrode is obtained by assembling three layers of GDH.

[0050] When using the prepared glucose PEC sensor for glucose detection, first, a series of glucose standard solutions with different concentrations are prepared using 0.01 M NAD solution containing 0.01 M PBS (the treatment method for the unknown solution is similar). Then, with the GDH / In 2 O 3 MTs / CF electrode as the working electrode, a platinum wire electrode as the counter electrode, and an Ag / AgCl electrode as the reference electrode to construct a three-electrode system. Using the prepared glucose solution containing coenzyme (nicotinamide adenine dinucleotide) as the electrolyte solution and a 410 nm LED light source as the excitation source, the glucose concentration in the unknown solution is detected by measuring the change in the photocurrent intensity of the system in combination with the standard curve method.

[0051] To study the feasibility of the designed glucose PEC sensing strategy, the present invention respectively tested the photocurrent responses of the In 2 O 3 / CP electrode to the PBS solution before and after adding glucose and the GDH / In 2 O 3 MTs / CF electrode to the glucose solution before and after adding NAD coenzyme. The results are as Figure 6 shown. Comparing curves (a) and (b), it can be seen that before assembling GDH, the In 2 O 3 MTs / CP electrode also has a certain photoelectric response to the glucose solution. From curve c, it can be seen that after assembling GDH, the photoelectric response of the GDH / In 2 O 3 MTs / CP electrode to the glucose solution is reduced compared with that before assembly. This is because the PDDA and GDH attached to the electrode surface reduce the conductivity of the electrode and slow down the electron transfer. When coenzyme NAD is added to the glucose solution, the photocurrent intensity of the GDH / In 2 O 3 MTs / CF electrode is increased by about 5 times compared with that of the electrode in the single glucose solution (curve d). This is mainly attributed to the fact that the GDH modified on the electrode not only generates the electron donor NADH by catalyzing the oxidation process of glucose but also realizes the catalytic cycle through the generation of the hole oxidation product NAD, thereby further amplifying the signal and significantly enhancing the photocurrent signal, which fully demonstrates that the constructed sensing strategy is feasible.

[0052] The selectivity test results of the glucose PEC sensor constructed by the present invention are as Figure 7As shown. It can be seen from the figure that, taking the photocurrent response of the PEC sensor to PBS as a reference, the increment of the response signal of the sensor to the glucose solution is about 5 times that of glutamic acid and 10 times that of glutathione or ascorbic acid at the same concentration. The data indicate that the PEC glucose sensor has the ability to selectively detect glucose and can resist certain impurity interferences.

[0053] In order to evaluate the linear response performance of the sensor to glucose, the present invention measured the optoelectronic response of the PEC glucose sensor to glucose solutions with different concentrations. In the concentration range of 0.1 mM - 10 mM, the intensity of the photocurrent has a good linear relationship with the logarithm of the glucose solution concentration, and the linear correlation coefficient is 0.9815.

[0054] The present invention provides an indium oxide microtube modified carbon fiber photosensitive electrode and its preparation method and application ideas and methods. There are many ways to specifically implement this technical solution. The above is only the preferred implementation mode of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and retouches can be made, and these improvements and retouches should also be regarded as the protection scope of the present invention. Each component not clearly defined in this embodiment can be implemented by existing technologies.

Claims

1. A carbon fiber photosensitive electrode modified with indium oxide microtubes, Characterized in that, It includes a carbon fiber electrode and indium oxide microtubes fixed on the surface of the carbon fiber electrode, and the indium oxide microtubes have a hollow tubular structure; The indium oxide microtubes are fixed on the surface of the carbon fiber electrode by a heat treatment method; The carbon fiber photosensitive electrode modified with indium oxide microtubes is specifically prepared through the following steps: (1) React terephthalic acid and indium nitrate hydrate in an organic solvent. The reaction product is subjected to solid-liquid separation, washing, and drying to obtain an In-MIL-68 intermediate with a solid hexagonal prism morphology; (2) Calcinate the In-MIL-68 intermediate obtained in step (1) to obtain indium oxide microtubes with a hollow tubular structure; (3) Disperse the indium oxide microtubes obtained in step (2) in water, then drop the dispersion on the surface of the carbon fiber electrode, dry it with an infrared lamp, and then calcine to obtain.

2. The preparation method of the carbon fiber photosensitive electrode modified with indium oxide microtubes according to claim 1, Characterized in that, In step (1), the organic solvent is N,N-dimethylformamide; the concentration of terephthalic acid in the organic solvent is 1 mg / mL to 2 mg / mL; the concentration of indium nitrate hydrate in the organic solvent is 1 mg / mL to 2 mg / mL; the reaction temperature is 110 °C to 130 °C, and the reaction time is 20 min to 40 min; the washing is repeated 2 to 3 times with absolute ethanol.

3. The preparation method of the carbon fiber photosensitive electrode modified with indium oxide microtubes according to claim 1, Characterized in that, In step (2), the calcination conditions are: heating up to 110 °C to 130 °C at a heating rate of 4 °C / min to 7 °C / min, calcining for 40 min to 90 min, and then heating up to 450 °C to 550 °C at a heating rate of 4 °C / min to 6 °C / min, and calcining for 1.5 h to 2.5 h.

4. The preparation method of the carbon fiber photosensitive electrode modified with indium oxide microtubes according to claim 1, Characterized in that, In step (3), the indium oxide microtubes are dispersed in water at a mass-volume ratio of 2 to 10 mg / mL, and the dispersion method is ultrasonic dispersion; the dispersion liquid is dropped onto the surface of the carbon fiber electrode in an amount of 1 to 1.5 μL / mm 2 of usage.

5. The preparation method of the carbon fiber photosensitive electrode modified with indium oxide microtubes according to claim 1, Characterized in that, In step (3), the calcination conditions are: heating up to 250 °C to 350 °C at a heating rate of 4 °C / min to 6 °C / min and maintaining for 40 min to 80 min.

6. The application of the carbon fiber photosensitive electrode modified with indium oxide microtubes according to claim 1 in constructing a photoelectrochemical sensor.

7. The application of the carbon fiber photosensitive electrode modified with indium oxide microtubes according to claim 1 in constructing a glucose photoelectrochemical sensor.

8. The application according to claim 7, Characterized in that, Glucose dehydrogenase is assembled on the carbon fiber photosensitive electrode modified with indium oxide microtubes according to claim 1 by an electrostatic assembly technique, and it is used as a working electrode to form a three-electrode system with a counter electrode and a reference electrode, and they are placed together in a glucose solution to be measured containing a coenzyme. The detection of glucose concentration is achieved by measuring the change in the photocurrent intensity of the system under light illumination conditions. The coenzyme described above includes nicotinamide adenine dinucleotide.

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