A method for improving hydrogen production efficiency by using Chlorella motors

Abstract

A method for improving hydrogen production efficiency by using Chlorella motors, belonging to the field of bioenergy technology. The present invention is to solve the problems that after the formation of Chlorella aggregates, it is difficult to redisperse them, resulting in a decrease in the acquisition rate of external electrons by internal Chlorella, a decrease in light energy utilization rate, and a decrease in its own survival rate, etc. The method is as follows: Using Chlorella pyrenoidosa as the living motor matrix, PDA-modified Ti3C2 two-dimensional material as the main shell material, and titanium dioxide (TiO2) nanomaterial as the motor driving material, a light-driven Chlorella motor with a yin-yang structure is constructed. By using its controllable "dispersion-aggregation" cyclic behavior, the effect of "accumulating electrons for hydrogen production when dispersed - consuming electrons for efficient hydrogen production when aggregated" of Chlorella is realized, thereby improving the survival rate, nutrient utilization rate and hydrogen production efficiency. The construction of this system is simple and the process is mild. The Ti3C2 shell has a protective effect on the biological activity and function of Chlorella, and the TiO2 shell has a photocatalytic function and a protective function.

Description

Technical Field

[0001] The present invention belongs to the technical field of bioenergy, and particularly relates to a method for improving hydrogen production efficiency by using Chlorella motors. Background Art

[0002] With the progress of technology and the development of the economy, people's demand for energy is increasing day by day. So far, the fuels used in various countries around the world are almost all fossil fuels, namely petroleum, natural gas and coal. The extensive exploitation and use of fossil fuels, on the one hand, exacerbate the potential energy shortage crisis; on the other hand, it aggravates environmental pollution and the greenhouse effect. Therefore, finding a clean, efficient and easily available renewable energy has become the research focus of scientific workers.

[0003] As a renewable energy source, hydrogen has attracted much attention from researchers due to its environmental friendliness and excellent energy conversion efficiency, and it is an ideal energy material for solving environmental problems and resource shortage problems. At present, the main methods for preparing hydrogen include steam reforming of hydrocarbons, pyrolysis, partial oxidation of hydrocarbons, methanol pyrolysis, and water electrolysis for hydrogen production, etc. These traditional preparation methods have high processing costs, cause a large waste of other energy sources, and also cause environmental pollution. Many drawbacks have hindered the wide application of hydrogen energy. Biological hydrogen production has the characteristics of wide source, mild process, pollution-free and strong sustainability, effectively avoiding the above problems and having great application potential. Among them, hydrogen production by photosynthetic microorganisms has gradually become a research hotspot in recent years due to its advantages such as being green and pollution-free. Hydrogen production by photosynthetic microorganisms refers to the method in which microorganisms decompose substrates through photosynthesis to produce hydrogen, which usually occurs in bacterial or algal cells. Among them, Chlorella is a common and easily artificially cultured green alga, which can use two independent but coordinated photosynthetic systems to generate electrons, protons and oxygen, and fix carbon dioxide. Among them, protons and electrons combine under the catalysis of hydrogenase to produce hydrogen. At present, in the biological hydrogen production method based on Chlorella, there are mainly two strategies. One is to improve the hydrogen production efficiency by designing an artificial cell wall (such as patent CN201910537314.8); the other is to construct Chlorella aggregates (an anaerobic space is formed inside the aggregates, thereby activating the hydrogenase inside Chlorella) to improve the hydrogen production efficiency (such as patent CN202010292040.3), but these methods all face the situation that it is difficult to redisperse after the formation of Chlorella aggregates, resulting in problems such as the decrease in the acquisition rate of external electrons by internal Chlorella, the decrease in light energy utilization rate, and the decrease in its own survival rate. How to improve the electron transfer efficiency on the surface of Chlorella and the self-survival rate and light energy utilization rate inside Chlorella aggregates to further improve the hydrogen production efficiency is still a scientific problem in the field of biological hydrogen production. Summary of the Invention

[0004] In view of the problems existing in the hydrogen production process of Chlorella, such as poor ultraviolet light tolerance of Chlorella, decreased survival rate of Chlorella caused by the formation of aggregates, low photon capture efficiency, and low light energy utilization rate, the present invention provides a method for improving hydrogen production efficiency by using a Chlorella motor. The present invention simply and efficiently constructs a light-driven Chlorella living motor with a yin-yang structure (hereinafter referred to as the Chlorella motor), realizes the dynamic regulation of the "dispersion-aggregation" state of the Chlorella motor, improves its survival rate and hydrogen production efficiency, and establishes a new method for improving biological hydrogen production efficiency based on the Chlorella motor.

[0005] The object of the present invention is achieved by the following technical solutions:

[0006] A method for improving hydrogen production efficiency by using a Chlorella motor, the method comprising:

[0007] Step 1: Prepare the main shell of the Chlorella motor with a Ti3C2 composite material modified with polydopamine (PDA). On this basis, deposit TiO2 nanoparticles unilaterally to construct the driving shell of the Chlorella motor, and obtain a Chlorella motor with a yin-yang structure;

[0008] Step 2: Add TAP medium to a sealed conical flask, put the Chlorella motor obtained in Step 1 into it, determine that the OD of Chlorella cells is 0.5, add the oxygen-consuming agent sodium sulfite, tightly stopper the flask, and irradiate it alternately with natural light and ultraviolet light in a light incubator at a temperature of 25-30 °C. The hydrogen production system is thus constructed, and its cumulative hydrogen production is measured. By means of the natural light-ultraviolet light alternating irradiation program, the "dispersion-aggregation" behavior of the Chlorella motor is controlled to achieve an increase in hydrogen production and hydrogen production efficiency.

[0009] Step 3: Take 200 μL of natural Chlorella pyrenoidosa and the Chlorella motor stock solution respectively in a confocal culture dish, observe the movement of natural Chlorella pyrenoidosa and the Chlorella motor under natural light and ultraviolet light irradiation respectively with an inverted optical microscope, use open-source Python software to track and mark the movement process and trajectory of the Chlorella motor, calculate the mean square displacement and movement rate of different Chlorella motors, obtain the movement performance parameters of the Chlorella motor, and establish a method for regulating the individual and group movements of the Chlorella motor.

[0010] Further, Step 1 is specifically:

[0011] (1) Prepare 0.02 mol / L -1The natural Chlorella pyrenoidosa was washed and centrifuged in a NaCl solution for 2 - 3 cycles, and then washed and centrifuged in water for 3 - 5 cycles. The natural Chlorella pyrenoidosa was placed in 10 mL of Tris buffer solution with an OD of 0.5 for the Chlorella pyrenoidosa cells. A dopamine solution was added, and the mixture was stirred at 200 - 400 rpm at room temperature for 2 h; centrifuged to collect, and then washed and centrifuged in Tris buffer solution for 2 - 3 cycles; The Ti3C2 powder was ultrasonically dispersed in 10 mL of Tris buffer solution, and the washed Chlorella pyrenoidosa was dispersed into the Ti3C2 powder solution. The mixture was stirred at 200 - 400 rpm at room temperature for 1 - 2 h, centrifuged to collect, and washed and centrifuged in Tris buffer solution for 2 - 3 cycles to obtain Chlorella pyrenoidosa with a PDA - Ti3C2 material coated on its surface;

[0012] (2) The Chlorella pyrenoidosa with a PDA - Ti3C2 material coated on its surface was dispersed in 10 mL of Tris buffer solution with an OD of 0.5 for the Chlorella pyrenoidosa cells. A dopamine solution was slowly added dropwise to the solution, and the mixture was stirred at 200 - 400 rpm at room temperature for 1 - 2 h, centrifuged to collect, and then washed and centrifuged in Tris buffer solution for 2 - 3 cycles to coat a layer of PDA; Then the above - modified Chlorella pyrenoidosa was dispersed in 10 mL of Tris buffer solution and allowed to stand for 0.5 - 2 h. The Chlorella pyrenoidosa coated with Ti3C2 sank to the bottom of the beaker. A TiO2 suspension was slowly added dropwise to the solution, and the mixture was allowed to stand for 1 - 2 h, centrifuged to collect, and then washed and centrifuged in Tris buffer solution for 2 - 3 cycles to achieve a single - side coating of a layer of TiO2 (the shell layer of titanium dioxide is a single layer because only one layer of PDA is used to connect titanium dioxide), obtaining a yin - yang - structure TiO2@Ti3C2@chlorella motor.

[0013] Further, in steps (1) and (2), the pH of the Tris buffer solution is 8.5 and the concentration is 50 mM.

[0014] Further, in steps (1) and (2), the rotation speeds for both the washing - centrifugation cycle and the centrifugation collection are 5000 - 8000 rpm.

[0015] Further, in step (1), the concentration of the dopamine solution is 3 - 5 mg / mL -1 , with a volume of 2 mL; the mass of the Ti3C2 powder is 20 mg. PDA has good adhesion, and Ti3C2 can be fixed on the surface of Chlorella pyrenoidosa by this method.

[0016] Further, in step (2), the concentration of the dopamine solution is 3 - 5 mg / mL -1 , with a volume of 2 mL; the concentration of the TiO2 suspension is 2 - 4 mg / mL -1, with a volume of 2 mL. Coating a layer of PDA on the surface of PDA / Ti3C2-coated Chlorella vulgaris and then unilaterally depositing a layer of TiO2 can obtain a yin-yang structure.

[0017] Furthermore, in step two, the natural light-ultraviolet light cyclic illumination program is to irradiate with natural light for 20 min and then irradiate with ultraviolet light for 5 min in a cycle. The power of the natural light lamp is 45 W, and the power of the ultraviolet lamp is 20 W. Sodium sulfite is an oxygen-consuming agent to ensure the activity of hydrogenase and achieve continuous hydrogen production; the cyclic illumination makes the Chlorella vulgaris motor continuously cycle between "aggregation-dispersion". When aggregating, electrons are consumed for efficient hydrogen production, and when dispersing, electrons are accumulated for hydrogen production and nutrients are absorbed, improving the hydrogen production efficiency and survival time of Chlorella vulgaris.

[0018] The beneficial effects of the present invention compared with the prior art are as follows:

[0019] 1. The Ti3C2 material has a protective effect on the biological activity and function of Chlorella vulgaris, and has ultra-high conductivity and a suitable Fermi level, which can promote the transfer of photo-generated electrons and inhibit their rapid recombination with photo-generated holes. Therefore, it can act as an electron transfer channel in the hydrogen production process of Chlorella vulgaris, thereby enhancing the hydrogen production efficiency.

[0020] 2. TiO2 can "turn harm into treasure" by absorbing ultraviolet light and carrying out a photocatalytic reaction to produce hydrogen, which can protect Chlorella vulgaris from the harm of ultraviolet light; at the same time, the photo-generated electrons produced by this catalytic process can be effectively conducted into the interior of Chlorella vulgaris through the PDA-modified Ti3C2 shell on the surface of Chlorella vulgaris and further used for hydrogen production, achieving a synergistic effect between the hydrogen production function of Chlorella vulgaris itself and the hydrogen production function of the shell material catalysis "complementing each other".

[0021] 3. The TiO2 nanoshell endows Chlorella vulgaris with a light-controlled movement behavior. Based on the controllable "dispersion-aggregation" behavior of the Chlorella vulgaris motor, it can effectively solve the technical problem of difficult dynamic regulation of Chlorella vulgaris aggregates, and realize the cycle process of "accumulating electrons for hydrogen production when dispersing - consuming electrons for efficient hydrogen production when aggregating", avoiding the problems of decreased survival rate, electron capture rate, and light energy utilization rate caused by long-term aggregation of Chlorella vulgaris. Therefore, it can further improve the hydrogen production efficiency and establish a new mechanism and new method for hydrogen production based on the controllable clustering of Chlorella vulgaris motors. Description of the Drawings

[0022] Figure 1 is a scanning electron microscope photograph of natural Chlorella pyrenoidosa;

[0023] Figure 2 is a transmission electron microscope photograph of natural Chlorella pyrenoidosa;

[0024] Figure 3 is a scanning electron microscope photograph of PDA-Ti3C2-modified Chlorella vulgaris;

[0025] Figure 4 Schematic diagram of the experimental method for preparing the Janus-structured Chlorella motors by unilateral deposition of TiO2 and controllable hydrogen production

[0026] Figure 5 Scanning electron microscope photograph of the Chlorella motors modified with TiO2-Ti3C2

[0027] Figure 6 Laser confocal fluorescence microscope photograph of the Janus-structured Chlorella motors

[0028] Figure 7 Optical microscope photograph of the aggregation state of the Chlorella motors

[0029] Figure 8 Optical microscope photograph of the dispersed state of the Chlorella motors

[0030] Figure 9 Movement trajectory diagram of the dispersed movement of the Chlorella motors under ultraviolet light irradiation

[0031] Figure 10 Movement trajectory diagram of the aggregated movement of the Chlorella motors under natural light irradiation

[0032] Figure 11 Movement trajectory diagrams of natural Chlorella pyrenoidosa and the Chlorella motors under different light conditions

[0033] Figure 12 Data diagram of the cumulative hydrogen production of natural Chlorella pyrenoidosa and the Chlorella motors under different light conditions Detailed implementation mode

[0034] The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments, but are not limited thereto. Any modifications or equivalent replacements made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention shall be covered by the protection scope of the present invention.

[0035] The Chlorella motors of the present invention effectively utilize ultraviolet light, provide a large number of photo-generated electrons through the TiO2 photocatalytic hydrogen production process, and can also transfer electrons to the interior of Chlorella for hydrogen production by using the PDA-modified Ti3C2 shell material, achieving the effect of synergistic hydrogen production. At the same time, the controllable collective movement behavior of the Chlorella motors can realize the dynamic regulation process of Chlorella aggregates, realizing the cycle process of "accumulating electrons for hydrogen production during dispersion - consuming electrons for efficient hydrogen production during aggregation". Based on the above advantages, establishing a new method for improving the efficiency of biological hydrogen production based on Chlorella motors is the core innovation point of the present invention.

[0036] The present invention aims to overcome the adverse effects of ultraviolet light on the survival ability and function of Chlorella during the photosynthetic hydrogen production process, and at the same time solve the problems such as the difficulty in redispersing Chlorella aggregates after their formation, resulting in a decrease in the acquisition rate of external electrons by internal Chlorella, a decrease in light energy utilization efficiency, and a decrease in its own survival rate. The specific method is as follows: Using Chlorella pyrenoidosa as the living motor matrix, PDA-modified Ti3C2 two-dimensional material as the main shell material, and titanium dioxide (TiO2) nanomaterial as the motor driving material, a light-driven Chlorella living motor with a yin-yang structure (referred to as the Chlorella motor) is constructed. Utilizing its controllable "dispersion-aggregation" cyclic behavior, the effect of "accumulating electrons for hydrogen production when dispersed - consuming electrons for efficient hydrogen production when aggregated" of Chlorella is realized, thereby improving the survival rate, nutrient utilization rate, and hydrogen production efficiency. The construction of this system is simple and the process is mild. The Ti3C2 shell has a protective effect on the biological activity and function of Chlorella, and the TiO2 shell has a photocatalytic function and a protective function. A new mechanism and new strategy for controllable cluster hydrogen production of the Chlorella motor are invented. The present invention can be used in the field of biological hydrogen production.

[0037] Example 1:

[0038] A preparation method of a light-driven Chlorella living motor for realizing efficient hydrogen production through controllable "dispersion-aggregation" behavior and an analysis of its hydrogen production amount are carried out according to the following steps:

[0039] I. Using natural Chlorella pyrenoidosa as the matrix, preparing a TAP medium and culturing it in a light incubator at a temperature of 25 - 30 °C under continuous light of 2500 LUX. When the number of natural Chlorella pyrenoidosa reaches the logarithmic growth phase, it is taken for use (OD = 0.5);

[0040] II. Preparing an NaCl solution (0.02 mol / L -1 ) and centrifuging the natural Chlorella pyrenoidosa for 2 - 3 times in a cycle (6000 rpm), then centrifuging it for 3 - 5 times in a cycle with clear water (6000 rpm). Placing the natural Chlorella pyrenoidosa in 10 mL of Tris buffer solution (pH = 8.5, 50 mM), with the OD of the natural Chlorella pyrenoidosa being 0.5, adding 2 mL of 3 mg / mL -1The dopamine solution was stirred at 300 rpm for 2 h at room temperature; then, it was centrifuged at 6000 rpm to collect, and then washed and centrifuged (6000 rpm) 2 - 3 times with Tris buffer solution (pH = 8.5, 50 mM); 20 mg of Ti3C2 powder was ultrasonically dispersed in 10 mL of Tris buffer solution (pH = 8.5, 50 mM), and the washed Chlorella pyrenoidosa was dispersed into the Ti3C2 powder solution, stirred at 300 rpm for 2 h at room temperature, centrifuged at 6000 rpm to collect, and washed and centrifuged (6000 rpm) 2 - 3 times with Tris buffer solution (pH = 8.5, 50 mM) to obtain Chlorella pyrenoidosa with a surface-coated PDA-Ti3C2 material;

[0041] III. The Chlorella pyrenoidosa with a surface-coated PDA-Ti3C2 material was dispersed in 10 mL of Tris buffer solution (pH = 8.5, 50 mM), and the OD of the Chlorella pyrenoidosa cells was 0.5. 2 mL of 3 mg / mL -1 dopamine solution was slowly added dropwise to the solution, stirred at 300 rpm for 2 h at room temperature, centrifuged at 6000 rpm to collect, and then washed and centrifuged (6000 rpm) 2 - 3 times with Tris buffer solution (pH = 8.5, 50 mM) to coat a layer of PDA; then the above-modified Chlorella pyrenoidosa was dispersed in 10 mL of Tris buffer solution (pH = 8.5, 50 mM), and the OD of the Chlorella pyrenoidosa cells was 0.5. It was left standing for 0.5 - 2 h to ensure that the modified Chlorella pyrenoidosa settled evenly to the bottom of the solution, and then 2 mL of 2 mg / mL -1 TiO2 suspension was slowly added dropwise to the solution. Without causing fluctuations in the overall solution, the TiO2 nanoparticles automatically settled onto the upper surface of the Chlorella pyrenoidosa at the bottom of the solution from above, and a layer of TiO2 was coated unilaterally. It was left standing for 1 h to ensure that TiO2 was stably modified onto the upper surface of the Chlorella pyrenoidosa (as shown in the attachment Figure 4 ); then it was centrifuged at 6000 rpm to collect, and then washed and centrifuged (6000 rpm) 2 - 3 times with Tris buffer solution (pH = 8.5, 50 mM) to obtain the TiO2@Ti3C2@chlorella motor with a yin-yang structure;

[0042] IV. 200 μL of the original solutions of natural Chlorella pyrenoidosa and Chlorella pyrenoidosa motors were respectively taken in a confocal culture dish, and the movement of natural Chlorella pyrenoidosa and Chlorella pyrenoidosa motors was observed under an inverted optical microscope under natural light and ultraviolet light irradiation respectively;

[0043] V. Add TAP medium and the oxygen-consuming agent sodium sulfite (0.8 mM) into a sealed conical flask, place the Chlorella motors into it, tightly stopper the flask, and irradiate it alternately with natural light - ultraviolet light (the power of the natural light lamp is 45 W and the power of the ultraviolet light lamp is 20 W) in an incubator at a temperature of 25 - 30 °C. Use a hydrogen detector to monitor the cumulative hydrogen production of the Chlorella motors at different time intervals.

[0044] Figure 1 It is the scanning electron microscope photograph of Chlorella pyrenoidosa in Step 1. It can be seen that the surface of the natural Chlorella cell wall is flat and smooth. Figure 2 It is the transmission electron microscope photograph of Chlorella pyrenoidosa in Step 1. It can be seen that the Chlorella cell wall is clean and smooth. Figure 3 It is the scanning electron microscope photograph of Chlorella coated with PDA-modified Ti3C2 in Step 2. It can be seen that the surface of Chlorella becomes rough after being coated with PDA-modified Ti3C2, and nano-sheet-like solids appear. Figure 4 It is the experimental schematic diagram for preparing Janus-structured Chlorella motors by unilateral deposition of TiO2. Figure 5 It is the scanning electron microscope photograph of the Chlorella motors in Step 3. It can be seen that on the basis of Figure 3 a new crystal layer appears, and the surface becomes more uneven. Figure 6 It is the laser confocal fluorescence microscope photograph of the Chlorella motors prepared with red fluorescence-modified TiO2 as the raw material in Step 3. It can be seen that an asymmetric yin-yang structure exists on the surface of the Chlorella motors. Figure 7 It is the inverted optical microscope photograph of the unirradiated Chlorella motors in the agglomerated state in Step 4. Figure 8 It is the inverted optical microscope photograph of the irradiated Chlorella motors in the dispersed state in Step 4. Figure 9 It is the movement trajectory diagram of the irradiated Chlorella motors in Step 4. It can be seen that the Chlorella motors move dispersedly under ultraviolet light irradiation. Figure 10 It is the movement trajectory diagram of the Chlorella motors irradiated with natural light after turning off the ultraviolet light in Step 4. It can be seen that the Chlorella motors move aggregately under natural light irradiation. Figure 11 It is the movement trajectory diagram of a single natural Chlorella and Chlorella motors under different light conditions in Step 4. Among them, 1 is the movement trajectory diagram of natural Chlorella under natural light irradiation, 2 is the movement trajectory diagram of natural Chlorella under ultraviolet light irradiation, 3 is the movement trajectory diagram of Chlorella motors under natural light irradiation, and 4 is the movement trajectory diagram of Chlorella motors under ultraviolet light irradiation. It can be seen that natural Chlorella performs Brownian motion under natural light irradiation, natural Chlorella performs Brownian motion under ultraviolet light irradiation but its activity weakens, Chlorella motors show enhanced Brownian motion under natural light irradiation, and Chlorella motors show a movement behavior away from the ultraviolet light under ultraviolet light irradiation. Figure 12The middle broken line 1 is the cumulative hydrogen production graph of the Chlorella motor in Step 5. It can be seen that the Chlorella motor has a relatively high hydrogen production amount and hydrogen production rate under the alternating irradiation of natural light and ultraviolet light.

[0045] Comparative Example 1:

[0046] Analysis of the hydrogen production amount of natural Chlorella pyrenoidosa under natural light irradiation.

[0047] I. Using natural Chlorella pyrenoidosa as the matrix, prepare TAP medium and culture it in a light incubator at a temperature of 25 - 30°C under continuous light of 2500 LUX. When the number of natural Chlorella pyrenoidosa reaches the logarithmic growth phase, take it (OD = 0.5);

[0048] II. Add TAP medium and the oxygen-consuming agent sodium sulfite (0.8 mM) to a sealed conical flask, put the Chlorella motor into it, and tightly stopper the flask with a cork. The hydrogen production system is then constructed;

[0049] III. Place the hydrogen production system in an environment irradiated by natural light, and use a hydrogen detector to monitor the cumulative hydrogen production amount of the Chlorella motor at different time periods.

[0050] Figure 12 The middle broken line 3 is the cumulative hydrogen production graph of natural Chlorella under natural light irradiation in Step 3. It can be seen that natural Chlorella has a relatively low hydrogen production amount and hydrogen production rate under natural light irradiation, and the hydrogen production starting point is relatively lagged.

[0051] Comparative Example 2:

[0052] Analysis of the hydrogen production amount of the Chlorella motor under natural light irradiation.

[0053] The difference between this comparative example and Example 1 is that in Step 5, the hydrogen production system is placed in an environment irradiated by natural light. Figure 12 The middle broken line 2 is the cumulative hydrogen production graph of the Chlorella motor under natural light irradiation in Step 5. It can be seen that the Chlorella motor has a relatively high hydrogen production amount and hydrogen production rate under natural light irradiation, but the hydrogen production starting point is relatively lagged, and the hydrogen production amount basically reaches saturation after 96 h, which means that the Chlorella motor under natural light irradiation can maintain hydrogen production activity. The existence of the motor in the form of aggregates improves the hydrogen production amount of Chlorella to a certain extent, but the long-term aggregation leads to a decrease in the survival rate, electron capture rate, and light energy utilization rate of Chlorella, thus resulting in a decrease in the hydrogen production rate.

[0054] Comparative Example 3:

[0055] Analysis of the hydrogen production amount of natural Chlorella under alternating natural light - ultraviolet light irradiation.

[0056] The difference between this comparative example and Comparative Example 1 is that in Step 3, the hydrogen production system is placed in an environment with alternating natural light and ultraviolet light irradiation. Figure 12 In Figure 12 , the broken line 4 is the graph of the cumulative hydrogen production of Chlorella vulgaris under the condition of alternating natural light and ultraviolet light irradiation in Step 3. It can be seen that Chlorella vulgaris has a very low hydrogen production under the condition of alternating natural light and ultraviolet light irradiation, and the hydrogen production rate is almost zero after 12 h, which means that Chlorella vulgaris dies under the condition of alternating natural light and ultraviolet light irradiation and cannot achieve hydrogen production.

[0057] Through the data analysis of the above examples and comparative examples, it can be seen that under the condition of alternating natural light and ultraviolet light irradiation, the effective hydrogen production time of unmodified Chlorella vulgaris is about 3 h, and the Chlorella vulgaris motor modified by Ti3C2 / TiO2 still maintains the hydrogen production performance after 144 h; the hydrogen production amount of the Chlorella vulgaris motor under natural light irradiation for 144 h is 1.72 μmol, and the hydrogen production amount of unmodified Chlorella vulgaris under natural light irradiation for 144 h is 1.20 μmol; the hydrogen production amount of the Chlorella vulgaris motor under the condition of alternating natural light and ultraviolet light irradiation for 144 h is 3.51 μmol, and the hydrogen production amount of unmodified Chlorella vulgaris under the condition of alternating natural light and ultraviolet light irradiation for 144 h is 0.07 μmol. The hydrogen production starting point of the Chlorella vulgaris motor is advanced by nearly 6 times, and the cumulative hydrogen production amount is increased by nearly 3 times.

Claims

1. A method for improving hydrogen production efficiency by using Chlorella motors, characterized in that: The method is as follows: Step 1: Prepare the main shell of the Chlorella motor with a polydopamine-modified Ti3C2 composite material. On this basis, construct the driving shell of the Chlorella motor by unilaterally depositing TiO2 nanoparticles to obtain a Chlorella motor with a yin-yang structure; Step 2: Add TAP medium to a conical flask, put the Chlorella motor obtained in Step 1 into it, determine that the OD of the Chlorella cells is 0.5, add the oxygen-consuming agent sodium sulfite, tightly plug the bottle with a stopper, seal the system, and irradiate it alternately with natural light and ultraviolet light in an incubator at a temperature of 25 - 30 °C. The hydrogen production system is then constructed, and its cumulative hydrogen production is measured; Through the natural light-ultraviolet light alternating irradiation program, control the "dispersion-aggregation" behavior of the Chlorella motor to improve the hydrogen production amount and hydrogen production efficiency.

2. A method for improving hydrogen production efficiency by using Chlorella motors according to claim 1, characterized in that: Specifically, Step 1 is as follows: (1) Configure a 0.02 mol / L NaCl solution to wash and centrifuge natural protein nuclear Chlorella 2 - 3 times in a cycle, and then wash and centrifuge it 3 - 5 times in a cycle with clean water. Place the natural protein nuclear Chlorella in 10 mL of Tris buffer solution, with the OD of the Chlorella cells being 0.

5. Add dopamine solution and stir at 200 - 400 rpm at room temperature for 2 h; Centrifuge and collect, then wash and centrifuge it 2 - 3 times in a cycle with Tris buffer solution; Ultrasonically disperse the Ti3C2 powder in 10 mL of Tris buffer solution, disperse the washed Chlorella into the Ti3C2 powder solution, stir at 200 - 400 rpm at room temperature for 1 - 2 h, centrifuge and collect, and wash and centrifuge it 2 - 3 times in a cycle with Tris buffer solution to obtain Chlorella coated with polydopamine-Ti3C2 material on its surface; (2) Disperse the Chlorella coated with polydopamine-Ti3C2 material in 10 mL of Tris buffer solution, with the OD of the Chlorella cells being 0.

5. Slowly drop dopamine solution into the solution and stir at 200 - 400 rpm at room temperature for 1 - 2 h, centrifuge and collect, and then wash and centrifuge it 2 - 3 times in a cycle with Tris buffer solution to coat a layer of polydopamine; Then disperse the above-modified Chlorella in 10 mL of Tris buffer solution and let it stand for 0.5 - 2 h. The Ti3C2-coated Chlorella sinks to the bottom of the beaker. Slowly drop TiO2 suspension into the solution, let it stand for 1 - 2 h, centrifuge and collect, and then wash and centrifuge it 2 - 3 times in a cycle with Tris buffer solution to achieve unilateral coating of a layer of TiO2, obtaining a yin-yang structure TiO2@Ti3C2@chlorella motor.

3. A method for improving hydrogen production efficiency by using Chlorella motors according to claim 2, characterized in that: In Steps (1) and (2), the pH of the Tris buffer solution is 8.5, 50 mM.

4. A method for improving hydrogen production efficiency by using Chlorella motors according to claim 2, characterized in that: In Steps (1) and (2), the rotation speeds for both the cycle washing and centrifugation and centrifugation collection are 5000 - 8000 rpm.

5. A method for improving hydrogen production efficiency by using Chlorella motors according to claim 2, characterized in that: In Step (1), the concentration of the dopamine solution is 3 - 5 mg / mL, the volume is 2 mL; the mass of the Ti3C2 powder is 20 mg.

6. A method for improving hydrogen production efficiency by using Chlorella motors according to claim 2, characterized in that: In Step (2), the concentration of the dopamine solution is 3 - 5 mg / mL, the volume is 2 mL; the concentration of the TiO2 suspension is 2 - 4 mg / mL, the volume is 2 mL.

7. A method for improving hydrogen production efficiency by using Chlorella motors according to claim 1, characterized in that: In Step 2, the natural light-ultraviolet light cyclic illumination program is to irradiate with natural light for 20 minutes and then irradiate with ultraviolet light for 5 minutes in a cycle. The power of the natural light lamp is 45 W, and the power of the ultraviolet lamp is 20 W.

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