Preparation method of photoelectrochemical sensor based on ternary heterojunction composite material

Abstract

The present invention relates to the technical field of photoelectrochemical sensors, and discloses a preparation method of a photoelectrochemical sensor based on a ternary heterojunction composite material. Concentrated hydrochloric acid is slowly dropped into ultrapure water, and then tetrabutyl titanate is added while stirring to obtain a mixed solution. The pretreated FTO electrode is placed into a high-pressure reactor, and the mixed solution is added into the reactor for hydrothermal reaction. Subsequently, annealing is carried out at a temperature of 450 - 550 °C for 2 h to obtain TiO2 / FTO; TiO2 / FTO is placed into a high-pressure reactor, 0.1 M copper sulfate solution and 0.1 M sodium thiosulfate solution are respectively added, and then hydrothermal reaction is carried out to obtain CuS / TiO2 / FTO; g-C3N4 is added into 20 mL of water, ultrasonically exfoliated for 2 h, and the supernatant is taken by centrifugation. CuS / TiO2 / FTO is placed in a petri dish, added with the above supernatant for soaking treatment, and then annealing can obtain g-C3N4 / CuS / TiO2 / FTO.

Description

Technical Field

[0001] The invention relates to the technical field of photoelectrochemical sensors, and in particular to a method for preparing a photoelectrochemical sensor based on a ternary heterojunction composite material. Background Art

[0002] Sesamol is a fat-soluble natural antioxidant derived from sesame oil. It has very strong antioxidant capacity both in vivo and in vitro and is often used as an antioxidant in medicine and food. SM has antioxidant, anti-aging, anti-mutagenic, anti-hepatotoxic, and anti-cancer activities, and is of great significance in the treatment of cancer, diabetes, cardiovascular disease, neurodegenerative diseases, metabolic disorders, and other diseases. In addition, adding sesame oil to corn oil, palm oil, and rice bran oil can inhibit the production of glycidyl esters in the deodorization process of edible oil to a certain extent; the natural antioxidant SM can further inhibit the generation of epoxyacyl radicals by scavenging ROO· free radicals, and can replace synthetic antioxidants as a stabilizer for edible oil quality. At present, many analytical test methods for detecting antioxidants have been developed, but they can only detect single-component antioxidants, and there are few reports on the exploration of binary or multi-component antioxidant mixtures.

[0003] Photoelectrochemical (PEC) analysis technology is an emerging technology developed based on the principle of light-to-electron conversion. It has attracted people's attention due to its advantages such as high sensitivity, low cost, simple operation and fast response speed. It is understood that the PEC sensing platform for detecting the mixed effects of SM and binary or multi-antioxidants such as vitamin E (VE), tert-butylhydroquinone (TBHQ), butylated hydroxyanisole (BHA), 2,6-di-tert-butyl-p-cresol (BHT) and propyl gallate (PG) has not been reported. The performance of PEC sensors depends largely on the properties of the photosensitive material and the photocurrent signal caused by the target. Therefore, choosing suitable semiconductor materials and designing innovative signal amplification strategies are extremely important for building an excellent PEC sensing platform.

[0004] In recent years, multi-component heterojunction composite materials with three-dimensional branched structures have attracted extensive attention from researchers because they can accelerate the transfer of electrons and increase the capture of photogenerated holes. One-dimensional titanium dioxide has high carrier mobility and thermal stability, but due to its wide band gap, its absorption in the visible light region is relatively weak. Copper sulfide with a narrower band gap is deposited on titanium dioxide nanorods to enhance the absorption of light, and then high-efficiency carbon trinitrogen tetranitrate is loaded to increase the contact area of ​​the reaction. A composite material with a ternary heterojunction is constructed as a PEC sensor to explore the synergistic effect between SM and binary and multi-component antioxidants such as VE, TBHQ, BHA, BHT, and PG. For this purpose, we propose a method for preparing a photoelectrochemical sensor based on a ternary heterojunction composite material. Summary of the invention

[0005] 1. Technical issues to be resolved

[0006] In view of the deficiencies in the prior art, the present invention provides a method for preparing a photoelectrochemical sensor based on a ternary heterojunction composite material, which solves the above-mentioned problems.

[0007] (II) Technical solution

[0008] To achieve the above-mentioned purpose, the present invention provides the following technical solution: a method for preparing a photoelectrochemical sensor based on a ternary heterojunction composite material, comprising the following steps:

[0009] Step 1: Slowly drop concentrated hydrochloric acid into ultrapure water, then add tetrabutyl titanate while stirring to obtain a mixed solution, put the pretreated FTO electrode into a high-pressure reactor, add the mixed solution into the reactor, and perform a hydrothermal reaction. Then, the temperature is 450-550℃, the annealing time is 2h, and the heating rate is 2℃ / min to obtain TiO 2 / FTO;

[0010] Step 2: TiO 2 / FTO was placed in a high-pressure reactor, and 0.1M copper sulfate solution and 0.1M sodium thiosulfate solution were added respectively, the volume of the copper sulfate solution was 0.025, 0.05, 0.1, 0.25, 0.5 or 1.0 mL, and the volume of the sodium thiosulfate solution was 4.975, 4.95, 4.9, 4.75, 4.5 or 4 mL, and then a hydrothermal reaction was performed to obtain CuS / TiO 2 / FTO;

[0011] Step 3: Add gC 3 N 4 Add 20 mL of water, ultrasonically strip for 2 h, centrifuge and take the supernatant, and separate the CuS / TiO 2 / FTO is placed in a watch glass, soaked in the above supernatant, and then annealed to obtain gC 3 N 4 / CuS / TiO 2 / FTO.

[0012] Preferably, the FTO pretreatment in the first step comprises washing with washing powder, acetone, ethanol and ultrapure water in sequence, and then drying with nitrogen.

[0013] Preferably, the annealing temperature in the first step is 500°C.

[0014] Preferably, the volumes of concentrated hydrochloric acid, water and tetrabutyl titanate in the first step are 15 mL, 15 mL and 500 μL, respectively.

[0015] Preferably, the volume of the copper sulfate solution in the second step is 0.25 mL, the volume of the sodium thiosulfate solution is 4.75 mL, the hydrothermal reaction conditions are 120° C., and the reaction time is 5 h.

[0016] Preferably, gC in the third step 3 N 4 The preparation steps are as follows: melamine is heated to 550°C at a rate of 2°C / min under a nitrogen atmosphere and maintained for 2 hours. After the reaction is completed, gC 3 N 4 .

[0017] Preferably, gC in the third step 3 N 4 The amount of addition is any one of 0.1, 1, 5, 10 or 20 mg.

[0018] Preferably, gC in the third step 3 N 4 The amount added was 10 mg.

[0019] Preferably, the soaking condition in the third step is soaking at 70° C. for 2 h, and the annealing condition is annealing at 550° C. for 2 h.

[0020] Preferably, the gC 3 N 4 / CuS / TiO 2 The ternary heterojunction composite material is used in the construction of photoelectrochemical sensors for detecting SM.

[0021] (III) Beneficial effects

[0022] Compared with the prior art, the present invention provides a method for preparing a photoelectrochemical sensor based on a ternary heterojunction composite material, which has the following beneficial effects:

[0023] 1. The preparation method of the photoelectrochemical sensor based on the ternary heterojunction composite material is based on gC 3 N 4 / CuS / TiO 2 The ternary heterojunction composite material has strong absorption in the ultraviolet and visible light regions, effectively solving the problems of low light utilization between multiple semiconductors, easy recombination of photogenerated carriers, and poor stability.

[0024] 2. The preparation method of the photoelectrochemical sensor based on the ternary heterojunction composite material is based on gC 3 N 4 / CuS / TiO 2The photoelectrochemical sensor was first applied to the highly sensitive and selective detection of SM, and the synergistic effect between SM and binary and multi-component antioxidants such as VE, TBHQ, BHA, BHT, and PG was demonstrated. The sensor is more sensitive, portable, and low-cost, opening up a new way for the detection of other antioxidants. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The material gC prepared in Example 1 3 N 4 / CuS / TiO 2 Scanning electron microscope (SEM), transmission electron microscope (TEM), high resolution (HRTEM) and elemental mapping images (EDS);

[0026] Figure 2 gC prepared in Example 1 3 N 4 / CuS / TiO 2 X-ray diffraction characterization diagram (A), electrochemical impedance spectroscopy (B), photocurrent spectra measured by different modified materials (C), UV-visible spectra (D), Kubelka-Munk function curve (E) and Mott-Schottky spectrum (F);

[0027] Figure 3 gC prepared in Example 1 3 N 4 / CuS / TiO 2 X-ray photoelectron spectroscopy (XPS);

[0028] Figure 4 gC prepared in Example 1 3 N 4 / CuS / TiO 2 Stability test (A) and anti-interference test (B) of photoelectrochemical sensor;

[0029] Figure 5 gC prepared in Example 1 3 N 4 / CuS / TiO 2 Photoelectric chemical sensor photocurrent response to six antioxidants and synergistic antioxidant performance test of binary mixed antioxidants;

[0030] Figure 6 gC prepared in Example 1 3 N 4 / CuS / TiO 2 Photoelectrochemical sensor testing of synergistic antioxidant performance of multi-component mixed antioxidants. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] Embodiment 1:

[0033] Based on gC 3 N 4 / CuS / TiO 2 Preparation of photoelectrochemical sensors

[0034] (1)TiO 2 Preparation of nanorods: 15 mL of concentrated hydrochloric acid was slowly added to 15 mL of ultrapure water, and then 500 μL of tetrabutyl titanate was added while stirring to obtain a mixed solution. A clean FTO electrode was placed in a high-pressure reactor, and an appropriate amount of the mixed solution was added to the reactor for hydrothermal reaction at 150°C for 5 h. After the reaction, the obtained TiO 2 / FTO was placed in a muffle furnace and annealed at 500℃ for 2h with a heating rate of 2℃ / min.

[0035] (2)TiO 2 CuS was deposited on the nanorods: the TiO 2 / FTO was placed in a high-pressure reactor, and 0.25 mL of copper sulfate solution (0.1 M) and 4.75 mL of sodium thiosulfate solution (0.1 M) were added respectively, mixed evenly, and then reacted at 120 ° C for 5 h to obtain CuS / TiO 2 / FTO.

[0036] (3)gC 3 N 4 Preparation: Melamine was heated to 550°C and maintained at a rate of 2.5°C / min for 2 h under a nitrogen atmosphere. The product was washed three times with ultrapure water and ethanol respectively. After drying at 60°C, gC 3 N 4 .

[0037] (4)gC 3 N 4 / CuS / TiO 2 Preparation of ternary heterojunction electrode materials: Weigh 10 mg gC 3 N 4 Add to 20 mL ultrapure water, sonicate for 2 h, then centrifuge at 10,000 rpm for 10 min, and take the supernatant for later use. 2 / FTO soaked in gC 3 N 4 The supernatant was heated at 70°C for 2h. Then it was placed in a tube furnace and reacted at 550°C for 2h under nitrogen atmosphere with a heating rate of 2°C / min.

[0038] Example 2, based on Example 1: referring to the conditions of step (2) in Example 1, CuS / TiO with deposition amounts of 0.5%, 1%, 2%, 5%, 10%, and 20% were prepared. 2 The volumes of 0.1M copper sulfate solution added were 0.025, 0.05, 0.1, 0.25, 0.5, and 1.0mL, respectively, and the volumes of 0.1M sodium thiosulfate solution added were 4.975, 4.95, 4.9, 4.75, 4.5, and 4mL, respectively.

[0039] Example 3, based on Example 1: referring to the conditions of step (3) in Example 1, gC 3 N 4 The doping amounts are 0.1, 1, 5, 10, and 20 mg of gC 3 N 4 / CuS / TiO 2 .

[0040] Material characterization and performance testing

[0041] (1) Analyze the samples using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Figure 1 As shown, Figure 1 A and B in gC 3 N 4 / CuS / TiO 2 SEM; C and D in the figure are gC 3 N 4 / CuS / TiO 2 TEM; From the above figure, we can see that the rod-shaped TiO 2 Uniformly grown on the FTO electrode, CuS nanoparticles are dispersed on the TiO 2 The nanorods were modified with gC 3 N 4 After that, TiO 2 The top of the nanorod is flower-shaped, which increases the reaction area. Figure E is gC 3 N 4 / CuS / TiO 2 HRTEM, d = 0.338nm and d = 0.268nm correspond to TiO 2The 204 and 200 crystal planes, d = 0.264nm, correspond to the crystal plane of CuS; Figure F is the mapping, and each element is clearly visible, further proving that the composite material was successfully synthesized.

[0042] (2) XRD analysis of gC 3 N 4 / CuS / TiO 2 Crystal form. Figure 2 As shown in A, curve gC 3 N 4 / CuS / TiO 2 The anatase TiO 2 (101) and (004) planes of (JCPDS No.21-1272), gC 3 N 4 In addition, it is also proved that the composite material prepared by high temperature reaction is composed of TiO 2 , gC 3 N 4 and CuS, and no impurity peak is generated.

[0043] (3) The conductivity of the material was studied using EIS. Figure 2 As shown in B, gC 3 N 4 / CuS / TiO 2 The arc diameter is the smallest, indicating that the composite material has lower electron transfer resistivity and better conductivity.

[0044] (4) Photocurrent test: A three-electrode system was used to test the modified TiO 2 , gC 3 N 4 , CuS, CuS / TiO 2 , gC 3 N 4 / CuS / TiO 2 The photoelectrochemical sensor is used as the working electrode, the platinum wire is used as the counter electrode, and the silver / silver chloride is used as the reference electrode. With 0.1M PBS as the buffer solution and an applied voltage of 0V, the photocurrent is tested under the irradiation of a 630nm laser light source, and the average value is taken after three repetitions. The photocurrent calculation formula is: ΔI=I 1 –I 0 (I 0 : Background current, i.e., the photocurrent of the buffer only; I 1 : contains the photocurrent of the object being measured). Figure 2 C in a 0 , b 0 、c 0 d 0, and e 0 TiO 2 , gC 3 N 4 , CuS, CuS / TiO 2 , gC 3 N 4 / CuS / TiO 2 The background current, a 1 、b 1 、c 1 d 1 , and e 1 123.46 μmol L -1 Photocurrent in SM. The composite material gC 3 N 4 / CuS / TiO 2 The photocurrent is significantly higher than that of a single substance, indicating that the electron-hole transmission speed of the composite material is increased and the electrical signal is enhanced.

[0045] (5) The samples were analyzed using UV-visible diffuse reflectance. Figure 2 As shown in D, TiO 2 There is strong absorption between 200-400nm, but almost no absorption between 400-800nm; CuS is deposited and gC is loaded 3 N 4 Afterwards, the absorption between 200-800nm ​​is enhanced, proving that the material composite has strong light absorption ability. Figure 2 E is the corresponding Kubelka-Munk diagram, and the TiO 2 、CuS / TiO 2 and gC 3 N 4 / CuS / TiO 2 band gap. Figure 2 F is the Mott-Schottky plot, and it can be calculated that the flat band potential of the composite material is -0.25V.

[0046] (6) XPS was used to further verify gC 3 N 4 / CuS / TiO 2 Components. Figure 3 It can be seen that each element exists in a single structure, further proving that gC 3 N 4 / CuS / TiO 2 Successful synthesis of nanosheets.

[0047] (7) Photoelectrochemical sensor anti-interference test: In the presence of 123.46 μmol L -1In the SM system, according to the concentration distribution characteristics of the interferents, 18 times of fructose, glucose, sucrose, L-malic acid, L-citric acid, ethanol, L-threonine, L-proline, L-lysine, L-histidine and 700 times of Na + , K + Mg 2+ , Ca 2+ Interference with the photocurrent response of the SM detection system, such as Figure 4 As shown in A. The results show that the sensing platform exhibits high selectivity for SM and has excellent anti-interference performance.

[0048] (8) Photoelectrochemical sensor stability test: Figure 4 As shown in B, in the presence of 1270.57 μmol L -1 In the SM system, the light was turned on and off continuously for 470 seconds, and no obvious photocurrent drop was observed, which indicates that gC 3 N 4 / CuS / TiO 2 The PEC sensor exhibited remarkable stability in the SM assay.

[0049] (9) Figure 5 As shown, gC 3 N 4 / CuS / TiO 2 The photoelectrochemical sensor tested the photocurrent response of different concentrations of SM, VE, TBHQ, BHA, BHT and PG, as well as the photocurrent response of SM mixed with VE, TBHQ, BHA, BHT, PG and other concentrations. At low concentrations, the photocurrent showed an additive effect, while at high concentrations, it showed a synergistic effect.

[0050] (10) Figure 6 As shown, gC 3 N 4 / CuS / TiO 2The photoelectric chemical sensor tested the photocurrents of binary mixed natural antioxidants (SM, VE), quaternary mixed artificial antioxidants (TBHQ, BHA, BHT, PG) and hexavalent antioxidants (SM, VE, TBHQ, BHA, BHT, PG) at the same concentration. The results showed that the photocurrent of binary mixed natural antioxidants (SM, VE) was 1.57 times larger than that of single SM and VE; the photocurrent response of quaternary mixed artificial antioxidants (TBHQ, BHA, BHT, PG) was 1.64 times larger than that of single TBHQ, BHA, BHT, PG, while the hexavalent antioxidants SM, VE, TBHQ, BHA, BHT, PG only increased by 1.56 times, indicating that the use of multiple antioxidants together will produce synergistic effects, but also antagonistic effects, so it is necessary to select appropriate antioxidants to achieve the best effect.

[0051] (11) Actual sample detection: The actual samples detected by the present invention are peanut oil and soybean oil. Table 1 below shows the analysis results of adding SM to actual samples of soybean oil and peanut oil. The results show that the recovery rates of the samples at different concentrations are very high, the relative standard deviations are low, and the precision and accuracy are very good.

[0052] Table 1 Analysis of SM content in soybean oil and peanut oil

[0053]

[0054] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. Preparation method of photoelectrochemical sensor based on ternary heterojunction composite material, It is characterized in that The following steps are involved: Step 1: Slowly add concentrated hydrochloric acid to ultrapure water, then add tetrabutyl titanate while stirring to obtain a mixed solution, put the pretreated FTO electrode into a high-pressure reactor, add the mixed solution into the reactor, perform a hydrothermal reaction, and then anneal at a temperature of 450-550°C for 2 hours at a heating rate of 2°C / min to obtain TiO 2 / FTO; Step 2: TiO 2 / FTO was placed in a high-pressure reactor, and 0.1M copper sulfate solution and 0.1M sodium thiosulfate solution were added respectively, the volume of the copper sulfate solution was 0.025, 0.05, 0.1, 0.25, 0.5 or 1.0 mL, and the volume of the sodium thiosulfate solution was 4.975, 4.95, 4.9, 4.75, 4.5 or 4 mL, and then a hydrothermal reaction was performed to obtain CuS / TiO 2 / FTO; Step 3: Add gC 3 N 4 Add 20 mL of water, ultrasonically strip for 2 h, centrifuge and take the supernatant, and separate the CuS / TiO 2 / FTO is placed in a watch glass, soaked in the above supernatant, and then annealed to obtain gC 3 N 4 / CuS / TiO 2 / FTO.

2. The method for preparing a photoelectrochemical sensor based on a ternary heterojunction composite material according to claim 1, Features: The fluorine-doped tin oxide (FTO) pretreatment in the first step includes washing with detergent, acetone, ethanol and ultrapure water in sequence, and then drying with nitrogen.

3. The method for preparing a photoelectrochemical sensor based on a ternary heterojunction composite material according to claim 1, Features: The annealing temperature in the first step is 500°C.

4. The method for preparing a photoelectrochemical sensor based on a ternary heterojunction composite material according to claim 1, Features: The volumes of concentrated hydrochloric acid, water, and tetrabutyl titanate in the first step were 15 mL, 15 mL, and 500 μL, respectively.

5. The method for preparing a photoelectrochemical sensor based on a ternary heterojunction composite material according to claim 1, Features: In the second step, the volume of the copper sulfate solution is 0.25 mL, the volume of the sodium thiosulfate solution is 4.75 mL, the hydrothermal reaction conditions are 120° C., and the reaction time is 5 h.

6. The method for preparing a photoelectrochemical sensor based on a ternary heterojunction composite material according to claim 1, Features: gC in the third step 3 N 4 The preparation steps are as follows: melamine is heated to 550°C at a rate of 2°C / min under a nitrogen atmosphere and maintained for 2 hours. After the reaction is completed, gC 3 N 4 .

7. The method for preparing a photoelectrochemical sensor based on a ternary heterojunction composite material according to claim 1, Features: gC in the third step 3 N 4 The amount of addition is any one of 0.1, 1, 5, 10 or 20 mg.

8. The method for preparing a photoelectrochemical sensor based on a ternary heterojunction composite material according to claim 1, Features: gC in the third step 3 N 4 The amount added was 10 mg.

9. The method for preparing a photoelectrochemical sensor based on a ternary heterojunction composite material according to claim 1, Features: The soaking condition in the third step is soaking at 70°C for 2 hours, and the annealing condition is annealing at 550°C for 2 hours.

10. Use of the photoelectrochemical sensor based on the ternary heterojunction composite material prepared by the preparation method according to claim 1 in constructing a photoelectrochemical sensor for detecting sesamol.

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