Method for regenerating coenzyme NADH (Nicotinamide Adenine Dinucleotide Hydrocarbon) through photocatalysis of continuous flow micro-reaction device

Abstract

The invention belongs to the field of biochemical engineering, and particularly relates to a method for regenerating coenzyme NADH through photocatalysis of a continuous flow micro-reaction device. The method comprises the following steps: (1) putting a g-C3N4-SO photosensitizer, an electron donor, an electron mediator and NAD < + > into a phosphate buffer solution, and uniformly mixing and stirring under a dark condition to obtain a photocatalytic reaction stock solution; and (2) putting the light-catalyzed reaction stock solution obtained in the step (1) into a micro-channel reaction device with illumination, and carrying out illumination treatment to continuously obtain the coenzyme NADH. According to the method, a g-C3N4-SO photosensitizer is adopted, and the coenzyme NADH is regenerated through photocatalysis of a continuous flow micro-reaction device. The photosensitizer is simple in synthesis step, low in cost, mild in reaction condition and simple in reaction device operation, the regeneration efficiency of the coenzyme NADH is remarkably improved, and the photosensitizer has a wide application prospect in the aspect of biocatalytically reducing carbon dioxide into high-value compounds.

Description

Technical Field

[0001] The present invention belongs to the field of biochemistry, and particularly relates to a method for efficiently photocatalytic regeneration of coenzyme NADH by a continuous flow microreactor. Background Art

[0002] In the process of rapid economic and social development of mankind, the overuse of fossil fuels has led to a large amount of anthropogenic carbon dioxide (CO2) emissions, triggering serious environmental problems such as global warming, sea level rise and extreme weather. Converting CO2 into fuels and chemicals is considered a promising strategy to alleviate the energy crisis. Photoenzymatic coupling catalysis combines the advantages of photocatalysis and enzymatic catalysis, and promotes the interconversion of CO2 and formic acid (HCOO - ) in the presence of reduced nicotinamide adenine dinucleotide (NADH). Among them, the coenzyme factor NADH plays an indispensable role, but its high price limits its large-scale application. Therefore, developing an efficient method for NADH regeneration has great application value.

[0003] The existing NADH regeneration technologies mainly include enzymatic, chemical, homogeneous catalysis, electrochemistry, photocatalysis and heterogeneous catalysis methods. Among them, photocatalytic NADH regeneration technology has received increasing attention due to its green, sustainable and external power source-free characteristics. Photocatalytic NADH regeneration uses solar energy to drive electrons to transfer from a photosensitizer to NAD + , thereby realizing the regeneration of NADH. Among them, the photosensitizer is the core of the entire photocatalytic coenzyme NADH regeneration system, and the development of stable and efficient photosensitizers is a current research hotspot. Inorganic photosensitizer carbon nitride has attracted wide attention due to its excellent electronic structure, good visible light response, low price and good chemical stability. However, its specific surface area is small, and the electron-hole recombination rate is relatively fast. Therefore, we can improve its photocatalytic ability by methods such as morphology regulation, doping elements, and constructing homo / heterojunctions. However, the existing photocatalytic technologies still have some limitations:

[0004] Currently, most photocatalytic reactions are carried out in a quartz reactor filled with the reaction stock solution. Under visible light irradiation, the photosensitizer quickly exerts its catalytic effect. However, this reaction device generally has the defect of a small light-exposed area of the reaction solution, and a large amount of photosensitizer in the solution cannot participate in the reaction in time, so the efficiency cannot be improved. For example, in the traditional batch reaction method mentioned in Patent CN1252255C, the yield of NADH is low and the reaction time is long. Traditional reactors are difficult to achieve continuous flow reactions, with low reaction efficiency and are not suitable for large-scale industrial applications.

[0005] The microreactor has a small pore size and high mass transfer efficiency. Therefore, combining photocatalysis with a microreactor and conducting a photoreaction in the microreactor allows the photosensitizer to be efficiently mixed in the reaction solution, greatly increasing the light-irradiated area of the reaction solution, enhancing the mass transfer of the reaction, and thus efficiently catalyzing the occurrence of the reaction. Huichao Lin et al. [1] Using a glass capillary and a PDMS microfluidic reactor, the coupling of photocatalysis and enzyme catalysis was achieved by immobilizing a photocatalyst and an enzyme. Although this system performed well in NADH regeneration and L-glutamate synthesis, its immobilization process was complex, and the reaction efficiency was limited by the activity of the immobilized catalyst. Alberto Bianco et al. designed a fully automated microfluidic system that significantly increased the yield of NADH by introducing oxygen microbubbles. However, this system has complex equipment, high costs, and a high degree of automation, making it suitable for laboratory research but not for small- and medium-scale production and industrial applications.

[0006] To solve the above problems, the present invention proposes a method for efficiently photochemically regenerating NADH through a continuous-flow microchannel reactor. This method uses a g-C3N4-SO photosensitizer, significantly improving the photocatalytic efficiency through a continuous-flow microreactor, while simplifying the operation steps, reducing costs, and being suitable for large-scale industrial applications.

[0007] [1] Huichao Lin, Yang Liu, Chonghui Yang, et al. Microfluidic artificial photosynthetic system for continuous NADH regeneration and l-glutamate synthesis[J].

[0008] [2] Alberto Bianco, Alexander H. McMillan, Carlo Giansante, et al. NADH Photoregeneration in a Fully Automated Microfluidic Setup[J]. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to provide a method for photocatalytic regeneration of coenzyme NADH through a continuous-flow microreaction device in view of the deficiencies of the prior art.

[0010] To solve the above technical problems, the present invention discloses a method for photocatalytic regeneration of coenzyme NADH through a continuous-flow microreaction device, comprising the following steps:

[0011] (1) Place the g-C3N4-SO photosensitizer, electron donor, electron mediator, and NAD + in a buffer solution, stir and mix evenly in the dark to obtain the photocatalytic reaction stock solution;

[0012] (2) Pump the photocatalytic reaction stock solution obtained in step (1) into a microreactor for light treatment, and collect the effluent to obtain the coenzyme NADH.

[0013] Among them, in step (1), the concentration of the g-C3N4-SO photosensitizer is 0.25 - 2.5 mg / mL, the concentration of the electron donor is 0.5 - 1.5 mmol / mL, the concentration of the electron mediator is 0.05 - 0.25 mmol / L, and the concentration of the NAD + is 0.5 - 1.5 mmol / L.

[0014] Preferably, the concentration of the g-C3N4-SO photosensitizer is 1 mg / mL.

[0015] Preferably, the concentration of the electron donor is 1 mmol / mL.

[0016] Preferably, the concentration of the electron mediator is 1 mmol / mL.

[0017] Preferably, the concentration of the NAD + is 1 mmol / L.

[0018] Among them, the buffer solution is a phosphate buffer solution, and its dosage is 0.5 - 2 mL.

[0019] Preferably, the dosage of the phosphate buffer solution is 1 mL.

[0020] Among them, the g-C3N4-SO photosensitizer is obtained by calcining after mixing melamine and melamine thiocyanate.

[0021] Among them, both melamine and melamine thiocyanate are solid-phase powders after grinding.

[0022] Specifically, for the grinding, the grinding time is 15 - 20 min.

[0023] Among them, the molar ratio of melamine to melamine thiocyanate is (9 - 11):1.

[0024] Preferably, the molar ratio of melamine to melamine thiocyanate is 10:1.

[0025] Among them, for the calcination, the conditions are: calcining at a temperature of 545 - 555 °C for 4.8 - 5.2 h.

[0026] Preferably, the calcination is carried out under the conditions of calcining at 550 °C for 5 h.

[0027] Among them, the solid phase obtained after calcination is washed and vacuum dried to prepare the g-C3N4-SO photosensitizer.

[0028] Specifically, for the washing, the obtained solid phase is washed with deionized water until the filtrate is clear and colorless; for the vacuum drying, the temperature of the vacuum drying is 65 - 75 °C and the time is 8 - 12 h.

[0029] Among them, the NAD is an electron acceptor.

[0030] Among them, the electron donor is triethanolamine and the electron mediator is [Cp*Rh(bpy) - (H2O)] 2+ 。

[0031] Specifically, for the [Cp*Rh(bpy) - (H2O)] 2+ , [Cp*RhCl2]2, anhydrous methanol and 2,2'-bipyridine are mixed until the suspension is in a bright orange-yellow clear state, and then anhydrous ether is added until an orange precipitate is formed. The precipitate is dried and dissolved in deionized water to obtain [Cp*Rh(bpy) - (H2O)] 2+ 。

[0032] Specifically, the molar ratio of [Cp*RhCl2]2 to 2,2'-bipyridine is 1:(1.8 - 2.2); the volume ratio of anhydrous methanol to anhydrous ether is (0.9 - 1.1):1; the dosage of deionized water is 48 - 52 mL.

[0033] Preferably, the molar ratio of [Cp*RhCl2]2 to 2,2'-bipyridine is 1:2.

[0034] Preferably, the volume ratio of anhydrous methanol to anhydrous ether is 1:1.

[0035] Preferably, the dosage of deionized water is 50 mL.

[0036] Among them, in step (1), for the stirring in the dark, the conditions are: under dark conditions, stirring at a stirring rate of 695 - 705 ppm for 25 - 35 min.

[0037] The preferred conditions are: under dark conditions, stirring at a stirring rate of 700 ppm for 30 min.

[0038] Among them, in step (2), for the pumping in, the flow rate is 20 - 100 μL / min.

[0039] Preferably, the flow rate of the pumping-in is 40 μL / min.

[0040] Among them, in step (2), the conditions of the light treatment are as follows: the light source used for the light treatment is visible light, the distance between the light source and the microchannel reaction device is 10-20 cm, the temperature is 20-30 °C, and the treatment time is 5-40 min.

[0041] Preferably, the conditions of the light treatment are as follows: the light source used for the light treatment is visible light, the distance between the light source and the microchannel reaction device is 15 cm; the temperature is room temperature, and the treatment time is 10 min.

[0042] Using the method of the present invention, through visible light excitation, the photogenerated electrons generated by g-C3N4-SO are captured by the electron mediator [Cp*Rh(bpy)-(H2O)] 2+ to generate the reduced state [Cp*Rh(bpy)-(H2O)]. Subsequently, [Cp*Rh(bpy)-(H2O)] transfers the photogenerated electrons and hydrogen protons in the solution to NAD + to generate biologically active NADH and restore the initial state of [Cp*Rh(bpy)-(H2O)] 2+ . At the same time, the photogenerated holes generated by g-C3N4-SO are consumed by the sacrificial agent (i.e., the electron donor triethanolamine), effectively inhibiting the recombination of electron-hole pairs, thereby improving the photocatalytic efficiency.

[0043] In the present invention, the microchannel reaction device includes a peristaltic pump, a microchannel reactor, and a receiver; the manufacturer of the peristaltic pump is Runze Fluid, and the product model is LM40B-RZ02-6-0.8-L; the microchannel reactor is a ring-shaped quartz glass tube with a volume of 0.4 mL and an inner diameter of 1 mm; the peristaltic pump, the microchannel reactor, and the photoreaction stock solution are connected by a pipe with an inner diameter of 1 mm; the materials of the pipes and other devices in the microchannel reaction device are polytetrafluoroethylene.

[0044] Beneficial effects:

[0045] The present invention provides a method for photocatalytic regeneration of coenzyme NADH through a continuous flow microreaction device. By doping non-metallic S and O elements into bulk carbon nitride, the electron-hole recombination rate is reduced, the charge transfer rate is increased, and at the same time, combined with the microchannel reactor device, the disadvantages of small light irradiation area and low reaction efficiency of the traditional quartz reactor are overcome. By constructing reasonable photocatalytic conditions, the photocatalytic NADH regeneration efficiency can reach 67%. The synthesis step of the photosensitizer is simple and the cost is low, and the reaction device is easy to operate, having broad application prospects in the biological catalysis of carbon dioxide reduction to high-value compounds. Description of the drawings

[0046] The following further specifically describes the present invention in conjunction with the accompanying drawings and specific embodiments, and the above and / or other advantages of the present invention will become clearer.

[0047] Figure 1 It is a schematic diagram of the microchannel photocatalytic reactor device in the embodiment of the present invention.

[0048] Figure 2 It is a standard curve graph of the product NADH in the embodiment of the present invention.

[0049] Figure 3 It is a Nyquist semicircle curve graph of the electrochemical impedance (EIS) spectra of different photosensitizers in the embodiment of the present invention.

[0050] Figure 4 It is a transient photocurrent response spectrum graph of different photosensitizers in the embodiment of the present invention.

[0051] Figure 5 It is a schematic diagram of the photocatalytic quartz reactor device in the embodiment of the present invention. Specific Embodiments

[0052] In the following embodiments, the experimental methods are all conventional methods unless otherwise specified; the reagents and materials can be obtained from commercial channels unless otherwise specified.

[0053] Melamine, melamine thiocyanate, [Cp*RhCl2]2, and 2,2'-bipyridine described in the following embodiments were purchased from Shanghai Macklin Biochemical Co., Ltd.; the NAD + was purchased from Shanghai Yuanye Co., Ltd., and triethanolamine was purchased from Shanghai Aladdin Co., Ltd.

[0054] The microchannel reaction device described in the following embodiments, as Figure 1 shown, includes a peristaltic pump, a microchannel reactor, and a receiver; among them, the peristaltic pump, the microchannel reactor, and the receiver are connected in series in sequence; the connection is through pipelines; the manufacturer of the peristaltic pump is Runze Fluid, and the product model is LM40B-RZ02-6-0.8-L.

[0055] In the following embodiments, the light treatment is carried out in a microchannel reaction device equipped with an XHA-350 simulated sunlight xenon lamp light source system.

[0056] In the following embodiments, the regeneration efficiency of the coenzyme NADH is detected by measuring the absorbance at 340 nm with a UV spectrophotometer and calculated through a standard curve. Among them, the standard curve is as Figure 2As shown in the figure, the specific establishment steps are as follows: NADH with a purity of 98% was selected to prepare a 0.2 mmol / L aqueous NADH solution as the stock solution, which was diluted into 6 gradients of 0.02, 0.04, 0.06, 0.08, 0.1, and 0.2 mmol / L respectively. The absorbance was measured at 340 nm. Based on these data, a standard curve of absorbance vs. NADH concentration was established, and the linear equation was obtained: y = 3.9454x + 0.0123, with a correlation coefficient of 0.9992.

[0057] Example 1: Preparation of g-C3N4-SO photosensitizer and electron mediator [Cp*Rh(bpy) - (H2O)] 2+

[0058] 1. Preparation of g-C3N4-SO photosensitizer

[0059] Melamine (0.1 moL) and melamine trithiocyanate (0.01 moL) with a molar ratio of 10:1 were added to a mortar and ground for 20 min until powdered to obtain a solid-phase powder. The obtained solid-phase powder was placed in a 100 mL crucible and calcined in a muffle furnace at 550 °C for 5 h under air conditions. Then, the calcined solid phase was washed with deionized water until the filtrate was clear and colorless, and vacuum dried at 70 °C for 10 h to obtain the one-step calcined g-C3N4-SO photosensitizer.

[0060] 2. [Cp*Rh(bpy) - (H2O)] 2+ Preparation

[0061] 61.8 mg of [Cp*RhCl2]2, 10 mL of anhydrous methanol, and 31.2 mg of 2,2'-bipyridine were mixed until the suspension was in a bright orange-yellow clear state, and then 10 mL of anhydrous ether was added to form an orange precipitate. The obtained precipitate was vacuum dried at 60 °C for 8 h and then dissolved in 50 mL of deionized water to obtain the [Cp*Rh(bpy) - (H2O)] 2+ .

[0062] Example 2: A method for highly efficient photocatalytic regeneration of coenzyme NADH through a continuous flow microreactor

[0063] (1) Mix 1 mg / mL of the one-step calcined g-C3N4-SO photosensitizer with 0.1 mmol / L [Cp*Rh(bpy) - (H2O)] 2+ , 1 mmol / mL of triethanolamine, and 1 mmol / L of NAD +It was placed in 1 mL of phosphate buffer solution, mixed evenly under dark conditions, and stirred at a stirring rate of 700 ppm for 30 min to obtain the photocatalytic reaction stock solution.

[0064] (2) At room temperature, the photocatalytic reaction stock solution obtained in step (1) was connected to a peristaltic pump through a pipe with an inner diameter of 1 mm. The flow rate of the peristaltic pump was set at 40 μL / min. When the reaction stock solution flowed into the microchannel reactor (with a volume of 0.4 mL and an inner diameter of 1 mm), a daylight xenon lamp located 15 cm away from the microchannel reactor in a straight line was turned on, and a fan was turned on for cooling to perform the light irradiation treatment. The residence time of the reaction solution in the microchannel reactor was 10 min, that is, the light irradiation treatment time of the reaction solution was 10 min. The coenzyme NADH could be continuously obtained. It was measured that the regeneration efficiency of the coenzyme NADH was 67%.

[0065] Example 3: A method for efficiently photocatalytic regeneration of coenzyme NADH by a continuous flow microreactor

[0066] The difference from Example 2 was that the g-C3N4-SO photosensitizer in step (1) was replaced with a bulk g-C3N4 photosensitizer in an equimolar amount, and the rest were the same as in Example 2.

[0067] Due to the high electron-hole recombination rate, slow charge transfer rate, and limited light absorption ability of the bulk g-C3N4 photosensitizer, its photocatalytic performance decreased significantly compared with the g-C3N4-SO photosensitizer, and the regeneration efficiency of the coenzyme NADH was only 16%.

[0068] Example 4: A method for efficiently photocatalytic regeneration of coenzyme NADH by a continuous flow microreactor

[0069] The difference from Example 2 was that the g-C3N4-SO photosensitizer prepared by one-step calcination in step (1) was changed to a two-step calcined g-C3N4-SO photosensitizer, and the rest were the same as in Example 2.

[0070] The specific preparation method of the two-step calcined g-C3N4-SO photosensitizer was as follows: Melamine and melamine thiocyanate in an equimolar amount were ground into powder. The melamine powder was calcined in one step under the same calcination conditions as in Example 1, and then melamine thiocyanate was added for secondary calcination under the same conditions to obtain the two-step calcined g-C3N4-SO photosensitizer.

[0071] It was measured that the regeneration efficiency of the coenzyme NADH was 46%. Compared with the two-step calcination, the g-C3N4-SO photosensitizer obtained by one-step calcination had more excellent photocatalytic performance and simpler synthesis steps.

[0072] Figures 3 - 4The photoelectrochemical properties of different photosensitizers in Examples 2 to 4 are shown. The charge transfer rate and separation rate inside the photosensitizer were tested by electrochemical impedance (EIS). Figure 3 The Nyquist semicircle curves of the photosensitizer obtained by one-step calcination (denoted as g-C3N4-SO-1 in the figure), the photosensitizer obtained by two-step calcination (denoted as g-C3N4-SO-2 in the figure), and the bulk g-C3N4 photosensitizer (denoted as g-C3N4 in the figure) are shown. By comparison, it is found that the Nyquist semicircle diameter of g-C3N4 is the largest, and the Nyquist semicircle diameters of g-C3N4-SO-1 and g-C3N4-SO-2 are significantly smaller than that of g-C3N4, indicating that the conductivity of the catalyst doped with non-metallic S and O elements has been significantly improved. In addition, the Nyquist semicircle diameter of g-C3N4-SO-1 is smaller than that of g-C3N4-SO-2. This result shows that the g-C3N4-SO photosensitizer obtained by the one-step calcination method has the highest charge separation and transport efficiency. Further, the transient photocurrent response values ( Figure 4 ) of g-C3N4-S-1, g-C3N4-SO-2, and g-C3N4 were tested under intermittent visible light irradiation. The transient photocurrent test shows that the photocurrent generated by g-C3N4-SO-1 under light irradiation is significantly higher than that of g-C3N4-SO-2 and g-C3N4, indicating that its separation efficiency of photogenerated carriers is higher. The reason is that S and O doping inhibits the recombination of photogenerated electron-hole pairs, thereby improving the photocurrent response. These results together show that the g-C3N4-SO photosensitizer obtained by one-step calcination significantly improves the charge separation efficiency, conductivity, and light absorption ability of g-C3N4, while inhibiting the recombination of photogenerated carriers, which is beneficial to the photocatalytic reaction.

[0073] Example 5: A method for efficiently photocatalytic regeneration of coenzyme NADH by a continuous flow microreactor

[0074] The difference from Example 2 is that the flow rate of the peristaltic pump described in step (2) is adjusted to 80 μL / min, and the rest are the same as in Example 2.

[0075] Since the flow rate of the peristaltic pump is 80 μL / min, the residence time of the reaction solution in the microchannel reactor is 5 min, that is, the light irradiation treatment time of the reaction solution is 5 min. The light irradiation time is short, and the degree of the photocatalytic reaction decreases relatively. It is measured that the regeneration efficiency of the coenzyme NADH is 43%.

[0076] Comparative Example 1: A method for photocatalytic regeneration of coenzyme NADH by a quartz reactor device

[0077] (1) Mix 1 mg / mL of the g-C3N4-SO photosensitizer obtained by one-step calcination with 0.1 mmol / L [Cp*Rh(bpy) - (H2O)]2+ 1 mmol / mL triethanolamine and 1 mmol / L NAD + were placed in 1 mL of phosphate buffer solution, mixed evenly under dark conditions, and stirred at a stirring rate of 700 ppm for 30 min to obtain the photocatalytic reaction stock solution.

[0078] (2) At room temperature, the photocatalytic reaction stock solution obtained in step (1) was placed in a quartz reactor with a volume of 15 mL. As Figure 5 shown, the daylight xenon lamp 15 cm away from the quartz reactor in a straight line was turned on, and the fan was turned on for cooling, and the light irradiation treatment was carried out. The light irradiation treatment time of the reaction solution was 10 min, and the coenzyme NADH was continuously obtained. After measurement, its regeneration efficiency was 21%.

[0079] Comparative Example 2: A method for photocatalytic regeneration of coenzyme NADH by a quartz reactor device

[0080] The difference from Comparative Example 1 was that the light irradiation treatment time in step (2) was adjusted to 60 min, and the rest was the same as in Comparative Example 1.

[0081] By further extending the light irradiation treatment time, the degree of photocatalytic reaction increased relatively. After measurement, the regeneration efficiency of the coenzyme NADH was 35%.

[0082] Based on Comprehensive Comparative Examples 1 and 2, compared with the traditional quartz reactor, the microchannel reactor was used in the present invention for photocatalytic regeneration of coenzyme NADH. In only 10 min, the regeneration efficiency of coenzyme NADH reached 67%, which was significantly higher than the regeneration efficiency of coenzyme NADH using a quartz reactor.

[0083] Comparative Example 3: A method for photocatalytic regeneration of coenzyme NADH using a g-C3N4 / UiO-66 composite photosensitizer

[0084] Taking the patent CN116003480A "A method for photochemical regeneration of coenzyme NADH" as Comparative Example 3, a g-C3N4 / UiO-66 composite photosensitizer was prepared, and then the g-C3N4 / UiO-66 composite photosensitizer and the electron mediator were ultrasonically mixed in a phosphate buffer solution. The obtained mixed solution was uniformly mixed with the electron donor and NAD to obtain the photocatalytic reaction stock solution. The specific implementation of the light irradiation treatment was as follows: the photocatalytic reaction stock solution was irradiated with visible light for 2 h at 30 °C, in an argon atmosphere and with circulating cooling water introduced to obtain the coenzyme NADH, and its regeneration efficiency of coenzyme NADH was 61%.

[0085] In summary, by doping non-metallic S and O elements into bulk carbon nitride, the present invention reduces the electron-hole recombination rate, improves the charge transfer rate, and at the same time combines with a microchannel reactor device to overcome the disadvantages of small light irradiation area and low reaction efficiency of traditional quartz reactors. By constructing reasonable photocatalytic conditions, the photocatalytic NADH regeneration efficiency can reach 67% within 10 minutes. The synthesis step of the photosensitizer is simple and low-cost, and the reaction device is easy to operate, showing broad application prospects in the biocatalytic reduction of carbon dioxide to high-value compounds.

[0086] The present invention provides a method for photochemically regenerating coenzyme NADH through a continuous flow microreaction device. There are many methods and ways to specifically implement this technical solution. The above is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention. Each component not clearly defined in this embodiment can be realized by existing technologies.

Claims

1. A method for photocatalytic regeneration of coenzyme NADH by a continuous flow microreactor, characterized in that: The steps include: (1) g-C3N4-SO photosensitizer, electron donor, electron mediator and NAD + Place in a buffer solution, stir and mix evenly in the dark to obtain a photocatalytic reaction stock solution; (2) The photocatalytic reaction stock solution obtained in step (1) is pumped into a microreactor for light treatment, and the effluent is collected to obtain the coenzyme NADH.

2. The method according to claim 1, characterized in that In step (1), the concentration of the g-C3N4-SO photosensitizer is 0.25-2.5 mg / mL, the concentration of the electron donor is 0.5-1.5 mmol / mL, the concentration of the electron mediator is 0.05-0.25 mmol / L, and the concentration of the NAD + The concentration is 0.5~1.5mmol / L.

3. The method according to claim 1 or 2, characterized in that: The g-C3N4-SO photosensitizer is prepared by mixing melamine and thiocyanuric acid and then calcining the mixture.

4. The method according to claim 3, characterized in that The molar ratio of melamine to thiocyanuric acid is (9-11):1; the calcination conditions are: calcination at a temperature of 545-555°C for 4.8-5.2h.

5. The method according to claim 1 or 2, characterized in that: The electron donor is triethanolamine, and the electron mediator is [Cp*Rh(bpy) - (H2O)] 2+ .

6. The method according to claim 5, characterized in that The [Cp*Rh(bpy) - (H2O)] 2+ , [Cp*RhCl2]2, anhydrous methanol and 2,2'-bipyridine are mixed until the suspension is clear, and then anhydrous ether is added to form a precipitate, and then the precipitate is vacuum dried and dissolved in deionized water to obtain [Cp*Rh(bpy) - (H2O)] 2+ .

7. The method according to claim 6, characterized in that The molar ratio of [Cp*RhCl2]2 to 2,2'-bipyridine is 1:(1.8-2.2); the volume ratio of anhydrous methanol to anhydrous ether is (0.9-1.1):

1.

8. The method according to claim 1, characterized in that In step (1), the stirring in the dark is carried out under the following conditions: stirring at a stirring rate of 695 to 705 ppm for 25 to 35 min in the dark.

9. The method according to claim 1, characterized in that: In step (2), the pumping has a flow rate of 20 to 100 μL / min.

10. The method according to claim 1, characterized in that In step (2), the light treatment is carried out under the following treatment conditions: the light source used for the light treatment is visible light, the distance between the light source and the microchannel reaction device is 10 to 20 cm, the temperature is 20 to 30° C., and the treatment time is 5 to 40 min.

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