A microbial photoelectrochemical system and its construction method and application

Abstract

The present invention relates to the field of photoelectrochemical conversion, and in particular to a microbial photoelectrochemical system, its construction method, and its application. The microbial photoelectrochemical system of the present invention comprises an anode chamber and a cathode chamber. The anode chamber is provided with an anode and a natural photosensitizer, and the cathode chamber is provided with a cathode and inoculated with a hybrid formed by combining microorganisms and a non-metallic photosensitizer. The anode chamber photosensitizer and cathode chamber hybrid are deposited on electrodes or discretely distributed in the electrode chamber. The microbial photoelectrochemical system of the present invention can achieve full-spectrum absorption of solar radiation and has excellent ability to generate and utilize photogenerated electrons and holes. It can be applied to fields such as water purification and low-molecular-weight hydrocarbon synthesis.

Description

Technical Field

[0001] The present invention relates to the field of photoelectrochemical conversion technology, in particular to a microbial photoelectrochemical system and a construction method and application thereof. Background Art

[0002] Microbial photoelectrochemical systems primarily consist of biocatalysts and photosensitizers. Their principle is that under illumination, the photosensitizer absorbs photon energy to generate photogenerated electrons. These electrons are then transferred to the active sites of biocatalysts (macroenzymes, microorganisms, etc.) through direct transfer or redox mediators, thereby driving energy metabolism in the organism. Microbial photoelectrochemical systems have become a hot topic of research due to their excellent catalytic performance and product selectivity.

[0003] Currently, the photosensitizers used in microbial photoelectrochemical systems are mainly inorganic semiconductors, such as cadmium sulfide (CdS) and indium phosphide (InP). Although inorganic semiconductors are relatively stable in chemical properties, these materials generally have shortcomings such as low electron separation efficiency due to the easy recombination of electrons and holes, heavy metal toxicity, and strong photocorrosion. In particular, these inorganic semiconductors have specific absorption spectra, and the efficiency of long-wave absorption is generally low, making it difficult to achieve full-spectrum absorption of light energy radiation, which restricts their application in microbial photoelectrochemical systems. Therefore, in order to improve the efficiency of light energy utilization, it is considered to use substances with different spectral absorption characteristics as photosensitizers for microbial photoelectrochemical systems to maximize energy utilization and improve performance.

[0004] Natural photosensitizers are green, non-toxic, cheap and easily available. Their unique advantages such as strong visible light absorption ability (400-700nm) and suitable redox potential can promote the transfer and utilization of photogenerated electrons, greatly improving the utilization rate of solar energy. However, it should be pointed out that natural photosensitizers have photodynamic antibacterial effects and can easily cause damage to microorganisms. In comparison, non-metallic photosensitizers have good compatibility with biocatalysts, but they usually require strong excitation light. Therefore, we can make full use of the characteristics of different photosensitizers to design an efficient microbial photoelectrochemical system to achieve full-spectrum absorption of solar radiation and apply it to fields such as water purification and low-molecular hydrocarbon synthesis. Summary of the Invention

[0005] The present invention aims to address at least one of the technical problems existing in the prior art. To this end, the first aspect of the present invention is to provide a microbial photoelectrochemical system with excellent photogenerated electron transfer and hole oxidation capabilities, which can be applied to fields such as water purification and low-molecular-weight hydrocarbon synthesis.

[0006] The second aspect of the present invention is to provide a method for constructing the microbial photoelectrochemical system.

[0007] The present invention also provides a method for using and applying the microbial photoelectrochemical system.

[0008] Specifically, the present invention adopts the following technical solutions:

[0009] The first aspect of the present invention is to provide a microbial photoelectrochemical system, which includes an anode chamber and a cathode chamber, wherein the anode chamber is provided with an anode and a natural photosensitizer, and the cathode chamber is provided with a cathode and inoculated with a hybrid formed by the combination of microorganisms and non-metallic photosensitizers, wherein the anode chamber photosensitizer and the cathode chamber hybrid are deposited on the electrode or discretely distributed in the electrode chamber.

[0010] Compared to the prior art, the hybrid in the cathode chamber of the microbial photoelectrochemical system described in the present invention is not only able to receive photogenerated electrons (excited by long-wavelength light energy) generated by the natural photosensitizer in the anode chamber, but can also generate photogenerated electrons (excited by short-wavelength light energy) itself, which are then efficiently used to reduce CO2 to produce low-molecular hydrocarbons such as methane and acetic acid. The combination of the natural photosensitizer in the anode chamber and the non-metallic photosensitizer in the cathode chamber can achieve full-spectrum absorption of solar radiation. At the same time, the highly oxidizing holes and reactive oxygen free radicals generated in the anode chamber can kill harmful microorganisms in the water, even bacteria and viruses, thereby achieving the purpose of water purification. In addition, the protons generated in the anode chamber can also be isolated by an ion exchange membrane to serve as a hydrogen source for the cathode.

[0011] In some examples of the present invention, in the hybrid, the microorganism and the photosensitizer are combined with each other through electrostatic adsorption, surface self-deposition, etc.

[0012] In some examples of the present invention, the microorganisms include any one or more of methanogens and acetogens, such as Methanosarcina barkeri, Moorellathermoacetica, and the like.

[0013] In some examples of the present invention, the cathode chamber non-metallic photosensitizer includes any one or more of polymerized nitrogen carbon, phosphorus quantum dots, and sulfur quantum dots.

[0014] In some examples of the present invention, the addition range of the non-metallic photosensitizer is 0.1 mg / mL to 5 mg / mL, preferably 0.1 mg / mL to 2 mg / mL, including but not limited to 0.1 mg / mL, 0.5 mg / mL, 1.0 mg / mL, 1.5 mg / mL, 2 mg / mL, etc.

[0015] In some examples of the present invention, the hybrid is obtained by culturing a microorganism in a culture medium containing a non-metallic photosensitizer.

[0016] In some embodiments of the present invention, the cathode has a porous structure. A porous structure facilitates the deposition and adhesion of the hybrid. Preferably, the cathode comprises one or more of carbon cloth and graphite plate.

[0017] In some embodiments of the present invention, the anode includes a substrate electrode and a natural photosensitizer attached to the surface of the substrate electrode. The natural photosensitizer includes any one or more of anthocyanins, lutein, lycopene, photosystem I, photosystem II, and the like. In the present invention, the selection of natural photosensitizers and non-metallic photosensitizers is based on the ability of the microbial photoelectrochemical system to absorb the full spectrum of solar radiation.

[0018] In some embodiments of the present invention, the loading amount of the natural photosensitizer on the substrate electrode surface is 10 μL / cm 2 ~100μL / cm 2 .

[0019] In some examples of the present invention, the natural photosensitizer includes at least one of a first natural photosensitizer and a second natural photosensitizer, the first natural photosensitizer includes at least one of anthocyanin, lutein, and lycopene, and the second natural photosensitizer includes at least one of photosystem I and photosystem II.

[0020] In some examples of the present invention, the mass ratio of the first natural photosensitizer to the second photosensitizer is 1:1 to 1:10.

[0021] In some embodiments of the present invention, the anode further comprises a redox polymer attached to the surface of the substrate electrode. Preferably, the redox polymer comprises poly(1-vinylimidazole-co-allylamine)-osmium(bipyridine) chloride (poly(1-vinylimidazole-co-allylamine)-Os(bipy)2Cl, P Os ), polybenzyl viologen (PBV 2+ ), polylysine benzoquinone (PBQ), or any one or more thereof. The redox polymer enables efficient electron transfer between different natural photosensitizers, thereby increasing the yield and utilization efficiency of generated electrons.

[0022] In some examples of the present invention, an anode photosensitizer layer is further provided on the surface of the substrate electrode, and the anode photosensitizer layer is provided between the substrate electrode and the first natural photosensitizer; the anode photosensitizer layer comprises a metal oxide, and the metal oxide comprises any one or more of TiO2, ZnO, and SnO2. Preferably, the anode photosensitizer layer has a honeycomb structure. Preferably, the anode photosensitizer layer is formed by sintering polymer microspheres and the metal oxide. After sintering, the surface of the substrate electrode can form a honeycomb structure that is easier to adhere to and fix. Preferably, the sintering temperature is 400 to 600°C, and the sintering time is 10 to 60 minutes.

[0023] In some examples of the present invention, the polymer microspheres include any one or more of polystyrene microspheres, polyacrylamide microspheres, and polyvinyl alcohol microspheres.

[0024] In some embodiments of the present invention, the loading amount of the metal oxide on the substrate electrode surface is 5 μL / cm 2 ~40 μL / cm 2 , preferably 10 μL / cm 2 ~30μL / cm 2 .

[0025] In some examples of the present invention, the mass ratio of the polymer microspheres to the metal oxide is 1:1 to 1:15, preferably 1:1 to 1:10.

[0026] In some examples of the present invention, the substrate electrode includes any one or more of FTO and ITO conductive glass.

[0027] In some embodiments of the present invention, the anode chamber and the cathode chamber are independent of each other. Preferably, the anode chamber and the cathode chamber are separated by an ion exchange membrane.

[0028] In some embodiments of the present invention, the anode chamber is filled with an electrolyte or wastewater. Preferably, the electrolyte comprises any one or more of Na / K phosphate buffer, citrate buffer, and borate buffer; and the wastewater comprises any one or more of domestic sewage and pharmaceutical wastewater.

[0029] In some embodiments of the present invention, the pH of the electrolyte is 6 to 8, preferably about 7.

[0030] In some examples of the present invention, the cathode chamber is filled with a culture medium, and the culture medium is inoculated with a hybrid formed by the microorganism and the non-metallic photosensitizer.

[0031] In some embodiments of the present invention, the culture medium can be flexibly adjusted according to the type of microorganism and the common technology in the field. For example, the composition of the culture medium can be set as: MgCl2 0.1-0.8g / L, CaCl2 0.05-0.3g / L, NH4Cl 0.05-0.3g / L, KH2PO4 0.1-0.5g / L, KCl 0.2-1g / L, HEPES (hydroxyethylpiperazine ethanesulfonic acid) 7.16g / L, NaHCO3 1-5g / L, Na2S 0-0.5g / L, NaAc 0-3g / L, cysteine ​​hydrochloride 0-0.1-0.3, trace element solution 0.2-3mL, selenite solution 0.2-3mL, vitamin solution 1-5mL, and the balance is water;

[0032] Each liter of trace element solution contains 30-80 mL HCl (0.5-4 M), 0.5-5 g FeCl2, 0.05-0.6 g ZnCl2, 0.05-0.5 g MnCl2, 0.05-0.3 g H3BO3, 0.01-0.1 g CoCl2, 1-10 mg CuCl2, 30-100 mg NiCl2, 40-150 mg Na2MoO4, and the balance is water;

[0033] Each liter of selenite solution contains 0.2-0.8 g NaOH, 0.5-5 mg Na2SeO3, 1-8 mg Na2WO4, and the balance is water;

[0034] Each liter of vitamin solution contains 0.01-0.1g p-aminobenzoic acid, 0.005-0.05g D-biotin, 0.005-0.05g α-lipoic acid, 0.05-0.3g D-pantothenate calcium, 0.05-0.3g vitamin B6, 0.01-0.1g folic acid, 0.01-0.1g niacin, 0.01-0.1g riboflavin, 0.005-0.05g vitamin B1, 0.01-0.1g vitamin B 12 , the balance is water.

[0035] The above culture medium is suitable for Methanosarcina barkeri.

[0036] Alternatively, the composition of the culture medium can be set to: glucose 15-20 g, yeast extract 2-8 g, tryptone 2-8 g, (NH4)2SO4 0.5-2 g, MgSO4 0.1-0.4 g, Fe(NH4)2SO4 0.01-0.08 g, CO(NO3)2 0.01-0.08 g, Na2WO4 0.001-0.05 g, Na2MoO4 0.001-0.05 g, Na2SeO3 0.0001-0.005 g, sodium thioglycolate (DIFCO) 0.1-1 g, N2HCO4 10-20 g, K2HPO4 4-10 g, KH2PO4 3-10 g, and the balance water per liter. This culture medium is suitable for growing Mollusca thermoacetica.

[0037] In some examples of the present invention, the anode is immersed in the electrolyte, and the cathode is immersed in the culture medium.

[0038] In some examples of the present invention, the anode and cathode are connected via an external circuit.

[0039] In some embodiments of the present invention, the anode and cathode chambers are light-transmissive. In the light-transmissive anode chamber, the natural photosensitizer in the anode can fully absorb long-wavelength light energy; in the light-transmissive cathode chamber, the non-metallic photosensitizer in the cathode can fully absorb short-wavelength light energy. The combination of the natural photosensitizer in the anode and the non-metallic photosensitizer in the cathode achieves full-spectrum absorption of solar radiation.

[0040] The second aspect of the present invention is to provide a method for constructing the microbial photoelectrochemical system, comprising the following steps: installing an anode in the anode chamber and adding a natural photosensitizer, installing a cathode in the cathode chamber and inoculating a hybrid formed by the combination of microorganisms and non-metallic photosensitizers to obtain the microbial photoelectrochemical system.

[0041] In some embodiments of the present invention, the method for constructing the hybrid comprises the following steps: mixing a culture medium inoculated with microorganisms with a non-metallic photosensitizer, and culturing in the dark to obtain the hybrid. After the hybrid is obtained by culturing, a relatively pure suspension of the hybrid can be obtained by centrifugation, washing, dilution and other steps. The centrifugation rate can be set to 5000-10000 rpm, preferably 6000-8000 rpm; the centrifugation time is 3-10 minutes, preferably 5-8 minutes. Both the washing and dilution processes can be carried out with physiological saline, and the bacterial solution is generally diluted to an OD of 0. 600 The value is 0.2 to 0.4. The culture medium can be flexibly adjusted according to the type of microorganism and the common technology in the field, and its composition is as described above.

[0042] In some embodiments of the present invention, the step of mixing the culture medium inoculated with microorganisms with the non-metallic photosensitizer is specifically as follows: inoculating the microorganisms into the culture medium for cultivation, and adding the non-metallic photosensitizer when the culture reaches the logarithmic phase.

[0043] In some embodiments of the present invention, the culture medium inoculated with microorganisms is mixed with the non-metallic photosensitizer and cultured in the dark for 10 to 36 hours, preferably 20 to 30 hours.

[0044] In some embodiments of the present invention, the anode construction method includes the following steps: coating a natural photosensitizer on the surface of a substrate electrode. Preferably, the anode construction method includes the following steps: coating the substrate electrode surface with a first natural photosensitizer, and then, after drying, sequentially coating with a mixture of other natural photosensitizers and a redox polymer. The coating methods for the mixture of the natural photosensitizer and the redox polymer independently include either dipping or drop coating. The drying process of the mixture of the natural photosensitizer and the redox polymer after coating is carried out in the dark.

[0045] In some examples of the present invention, the natural photosensitizer can be extracted from plants according to common techniques in the art.

[0046] For example, anthocyanins can be isolated and extracted from anthocyanin-containing plant materials such as black wolfberry, purple cabbage, flower petals, and purple sweet potatoes. For example, the anthocyanin-containing plant materials are dried and then crushed, and then subjected to alcohol extraction, solid-liquid separation, and concentration under light-proof conditions to obtain anthocyanins. The alcohol extraction preferably uses an ethanol-water solution with a volume fraction of 20% to 60% at a temperature of 40 to 50°C.

[0047] Lutein can be isolated and extracted from lutein-containing plant materials such as marigold petals. For example, the lutein-containing plant material is dried and crushed, then added to a solution containing an extractant consisting of THF, KOH, and ethanol (volume ratio of 1:1-2:1-2). The mixture is reacted under a protective atmosphere for 1-5 hours. After solid-liquid separation, the mixture is concentrated to obtain a paste. The paste is then dissolved in an ethanol-water solution (volume ratio of 1:1-3), the pH is adjusted to neutral, and the extract is centrifuged to remove the supernatant to obtain lutein. The reaction temperature can be 10-30°C, preferably 20-30°C.

[0048] Lycopene can be isolated and extracted from lycopene-containing plant materials, such as tomatoes. For example, the lycopene-containing plant material can be dried and crushed, and then extracted using a butylated hydroxytoluene solution. The butylated hydroxytoluene solution is preferably a solution of butylated hydroxytoluene in a mixed solvent of vegetable oil and ethanol. The extraction temperature is preferably 30-60°C, preferably 40-50°C, and the extraction time is 20-60 minutes, preferably 30-50 minutes. After the extraction, post-processing can be performed by solid-liquid separation, separation of the oil from the ethanol, and concentration.

[0049] Photosystem II and photosystem I can be isolated and extracted from chlorophyll-containing plant materials such as spinach leaves. For example, a culture medium (pH = 6.8-8) containing NaCl (100-300 mM) and Na / K phosphate buffer (20-80 mM) is mixed with the chlorophyll-containing plant material and crushed, and the chloroplasts are separated by filtration, centrifugation, and other steps; the separated chloroplasts are placed in a culture medium (pH = 6.9) containing sucrose (100-500 mM), NaCl (30-80 mM), and Na / K phosphate buffer (30-80 mM) to obtain a chlorophyll suspension; a surfactant (such as Triton-100) is mixed with the chlorophyll suspension, and the precipitate is collected by centrifugation to obtain photosystem II. More specifically, a culture medium (pH = 6.8-8) containing NaCl (100-300 mM) and Na / K phosphate buffer (20-80 mM) is mixed with a chlorophyll-containing plant material and crushed, filtered and centrifuged to obtain a precipitate; the precipitate is resuspended in a culture medium and centrifuged to obtain a supernatant, the precipitate obtained after centrifugation of the supernatant is suspended in a NaCl solution (0.005-0.03 M), and the precipitate is removed by centrifugation; the supernatant is centrifuged to collect chloroplasts; the chloroplasts are placed in a culture medium (pH = 6.9) containing sucrose (100-500 mM), NaCl (30-80 mM) and Na / K phosphate buffer (30-80 mM) to obtain a chlorophyll suspension; a surfactant (such as Triton-100) is mixed with the chlorophyll suspension, and the precipitate is collected by centrifugation to obtain photosystem II.

[0050] For example, a culture medium (pH 6.8-8) containing Tricine-NaOH (30-80 mM) and sorbitol (0.1-1 M) is mixed with a chlorophyll-containing plant material and crushed, and the chloroplasts are separated by filtration, centrifugation and other steps; the separated chloroplasts are washed in a Na-EDTA solution (2-8 mM, pH 6.8-8), then resuspended in water and dissolved with a surfactant (such as Triton-100) to obtain photosystem I.

[0051] Among them, since photosystem II and photosystem I will be severely damaged by high temperature stress when the temperature is higher than 45°C, the preparation procedures of photosystem II and photosystem I are all completed at low temperatures, such as below 40°C, preferably 0-30°C, and more preferably 0-10°C.

[0052] The above is only an example of a method for constructing a typical natural photosensitizer, and is not actually limited thereto. Any other method that can obtain a natural photosensitizer is applicable to the present invention.

[0053] In some examples of the present invention, the method for preparing the anode further includes coating polymer microspheres and any one or more of TiO2, ZnO, and SnO2 on the surface of the substrate electrode before coating the natural photosensitive material, and then performing a sintering step.

[0054] A third aspect of the present invention provides a method for using the microbial photoelectrochemical system, comprising the step of irradiating the anode of the microbial photoelectrochemical system with light. The microbial photoelectrochemical system of the present invention can achieve water purification and low-molecular hydrocarbon synthesis under light.

[0055] In some embodiments of the present invention, the illumination is intermittent or direct illumination.

[0056] In some embodiments of the present invention, the intermittent illumination parameters are 5 to 20 minutes of illumination and 100 to 120 minutes of darkness as one cycle, which is repeated; preferably, 10 minutes of illumination and 110 minutes of darkness as one cycle, which is repeated.

[0057] In some embodiments of the present invention, the wavelength of the illumination is 380 to 780 nm. The microbial photoelectrochemical system of the present invention can achieve full spectrum absorption.

[0058] In some embodiments of the present invention, the intensity of the light is 0.1 to 50 mW / cm 2 , preferably 0.5 to 10 mW / cm 2 .

[0059] The fourth aspect of the present invention is the use of the microbial photoelectrochemical system in water purification and / or synthesis of low molecular weight hydrocarbons. Preferably, the low molecular weight hydrocarbons include any one or more of methane, acetic acid, formic acid, and methanol.

[0060] Compared with the prior art, the present invention has the following beneficial effects:

[0061] The present invention provides a novel microbial photoelectrochemical system. The anode chamber contains an anode and a natural photosensitizer, while the cathode chamber contains a cathode inoculated with a hybrid formed by combining microorganisms and a non-metallic photosensitizer. The anode chamber photosensitizer and cathode chamber hybrid are deposited on the electrodes or discretely distributed within the chambers. This microbial photoelectrochemical system can absorb the entire spectrum of solar radiation and exhibits excellent generation and utilization of photogenerated electrons and holes. It has applications in water purification, low-molecular-weight hydrocarbon synthesis, and other fields.

[0062] Moreover, the raw materials required for the microbial photoelectrochemical system of the present invention are natural, harmless, inexpensive and easily available, the preparation process is simple, and it has high economic, energy, environmental and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 Schematic diagram of the working principle of the microbial photoelectrochemical system of Example 1.

[0064] Figure 2 These are the test results of methane production of the microbial photoelectrochemical system of Example 1 and Comparative Examples 1 to 3.

[0065] Figure 3 These are the test results of acetic acid production of the microbial photoelectrochemical system of Example 2 and Comparative Examples 4 to 6.

[0066] Figure 4 These are the test results of methane production of the microbial photoelectrochemical system of Example 3 and Comparative Examples 7 to 9.

[0067] Figure 5 (a) methane production test results and (b) water purification effects of the microbial photoelectrochemical systems of Example 3 and Comparative Examples 10-11. DETAILED DESCRIPTION

[0068] The technical solutions of the present invention are further described below with reference to specific examples. The raw materials used in the following examples, unless otherwise specified, can all be obtained from conventional commercial sources; the processes used, unless otherwise specified, are all conventional processes in the art.

[0069] The construction methods, technical parameters or sources of the materials required for the following embodiments or comparative examples are as follows:

[0070] (1) Photosystem II

[0071] Photosystem II was isolated from spinach leaves using the following steps:

[0072] Since photosystem II will be severely damaged by high temperature stress when the temperature is higher than 45°C, the preparation process of photosystem II in this embodiment is completed at 4°C.

[0073] Spinach leaves were mixed with a medium containing 200 mM NaCl and 50 mM Na / K phosphate buffer (pH = 7.8), crushed, and filtered through 16 layers of gauze to obtain a green juice. The filtered green juice was centrifuged, and the precipitate was resuspended in the above-mentioned medium (medium containing 200 mM NaCl and 50 mM Na / K phosphate buffer (pH = 7.8)) and centrifuged to obtain a supernatant. The precipitate obtained after centrifugation of the supernatant was suspended in 0.01 M NaCl solution and allowed to stand for 10 minutes. The suspension was then centrifuged for 5 minutes to remove the precipitate. The supernatant was centrifuged to collect chloroplasts, and the chloroplasts (chlorophyll concentration of approximately 2 mg / mL) were placed in a medium containing 300 mM sucrose, 50 mM NaCl, and 50 mM Na / K phosphate buffer (pH = 6.9) to obtain a chlorophyll suspension. An aqueous solution of Triton-100 (20% w / v) was mixed with the chlorophyll suspension and stirred until the ratio of Triton-100 to chlorophyll reached 25:1 (w / w). After gentle stirring for 30 minutes, the resulting precipitate was collected by repeated centrifugation and placed in 40 mM Na / K phosphate buffer (pH = 6.9). The suspension was centrifuged twice again to obtain a precipitate. The final precipitate was used as the photosystem II particles in the experiment and was stored in the dark until further use.

[0074] (2) Photosystem I

[0075] Photosystem I was isolated from spinach leaves. Since Photosystem I would be severely damaged by high temperature stress when the temperature is higher than 45°C, the preparation process of Photosystem I in this example was completed at 4°C.

[0076] Spinach leaves were mixed with a medium containing 50 mM Tricine-NaOH and 0.4 M sorbitol (pH 7.8) and disrupted. Chloroplasts were isolated by filtration and centrifugation. The isolated chloroplasts were washed in 5 mM Na-EDTA (pH 7.8) and then resuspended in deionized water to a chloroplast concentration of 0.8 mg Chl / mL. Photosystem I was then solubilized in Triton-100 and stored at -80°C until use.

[0077] (3) Anthocyanins

[0078] Anthocyanins are isolated and extracted from purple sweet potatoes. The specific steps are as follows:

[0079] Purple sweet potatoes with a high anthocyanin content were selected and sliced, then vacuum-dried at 50°C for several hours. The dried purple sweet potatoes were then ground into fine granules or powder. In the dark, the ground purple sweet potatoes were immersed in a 50% ethanol extraction solution (purple sweet potato: extraction solution = 1g: 5mL). Extraction was performed in a 50°C water bath with stirring for 90 minutes. The extract was centrifuged at 10,000 rpm for 10 minutes to obtain the supernatant, which was then rotary evaporated to concentrate the anthocyanins and stored in the dark for later use.

[0080] (4) Lutein

[0081] Lutein is isolated and extracted from marigold. The specific steps are as follows:

[0082] Marigold petals were washed, dried, and freeze-dried. The dried petals were then crushed and sieved. The petal powder was then added to a solution of THF, KOH, and ethanol (1:1:1 by volume) in a 1:5 ratio. The mixture was allowed to react at room temperature for 2 hours under nitrogen. The solution was filtered to remove scum and then concentrated by rotary evaporation to obtain a paste. The paste was then dissolved in ethanol-water (1:1 by volume) to obtain an extract. The pH of the extract was adjusted to neutral with acetic acid. The extract was centrifuged and the supernatant removed to obtain crude lutein.

[0083] (5) Lycopene

[0084] Lycopene is isolated and extracted from tomatoes. The specific steps are as follows:

[0085] Tomato peels were dried and crushed in the dark. The tomato samples were extracted with a mixed solvent (a mixture of vegetable oil and ethanol) containing 0.05% butylated hydroxytoluene (tomato: extraction solution = 1 g: 50 mL) at 45°C for 45 minutes. The extracted samples were then filtered and allowed to stand for 30 minutes to ensure separation of the oil and ethanol. The lycopene was then concentrated by rotary evaporation and stored in the dark until further use.

[0086] (6) Substrate electrode

[0087] Take 1 mL of polystyrene microsphere solution and centrifuge, discard the supernatant, mix the precipitate with 130 mg / mL TiO2 solution, and apply 200 μL of the mixed liquid to the anode electrode (the application area is 5 cm 2 ) and calcined in a muffle furnace at 500°C for 20 minutes to obtain an IO-TiO2 film (polystyrene microsphere-TiO2 film). After cooling to room temperature and cleaning with UV / ozone cleaner for 15 minutes, a substrate electrode was obtained, labeled as an IO-TiO2 electrode. The mass ratio of polystyrene microspheres to TiO2 was 1:5, and the TiO2 loading on the electrode surface was 20 μL / cm 2 .

[0088] (7) Polymerized carbonized nitrogen

[0089] Polymerized nitrogen carbide, CAS number: 32518-77-7. The molecular weight of the polymerized nitrogen carbide is 201.15 g / mol, and the optical band gap is 2.72 eV (wherein the valence band is 1.72 eV and the conduction band is -1 eV).

[0090] (8) Redox polymer P Os

[0091] Poly (1-vinylimidazole-allylamine) -osmium (bipyridine) chloride, namely P Os .

[0092] (9) Methanosarcina barkeri

[0093] Methanosarcina barkeri was purchased from the German Collection of Microorganisms (Deutsche Sammlungvon Mikroorganismen und Zellkulturen) with the collection number DSM-800.

[0094] (10) Moorella thermoacetica

[0095] Moorella thermoacetica was purchased from the American Type Culture Collection with the accession number ATCC 39073.

[0096] Example 1

[0097] This embodiment provides a microbial photoelectrochemical system, the construction method of which includes the following steps:

[0098] 1) Preparation of anthocyanin-photosystem II anode

[0099] The anode substrate electrode was immersed in an anthocyanin solution with a concentration of about 3%, and then dried at 4°C in the dark for 24 hours to obtain an anthocyanin-modified anode. 2 ) and redox polymer P Os The mixture (10 mg / mL) was added dropwise to the anthocyanin-modified anode and dried in the dark at room temperature for 30 minutes to prepare the anthocyanin-photosystem II anode. The electrode was rinsed before use to remove loose surface matter.

[0100] 2) Preparation of Methanosarcina barkeri-polymerized carbonized nitrogen hybrids

[0101] Methanosarcina barkeri was inoculated into acetic acid medium with a pH of 6.9 (see Table 1 for the recipe) at a volume ratio of 20% and cultured at 37±2°C. When Methanosarcina barkeri reached the logarithmic phase, 1 mg / mL polynitrogen carbonate was added and the cells were cultured in an incubator in the dark for 24 hours to form a Methanosarcina barkeri-polynitrogen carbonate hybrid. After 24 hours, the cells were centrifuged at 7500 rpm for 6 minutes and washed three times with saline. The bacterial suspension was finally diluted with saline to a concentration of OD 0. 600 value to 0.3.

[0102] 3) Construction and assembly of microbial photoelectrochemical systems

[0103] Take a glass container with a bottom diameter of 5 cm and pass it through a cation selective exchange membrane (working area 5.5 cm 2 ) is divided into two chambers (anode chamber and cathode chamber), and the container is fixed with an iron clamp to prevent leakage. PBS buffer with a pH of 7.0 is added to the anode chamber. The anthocyanin-photosystem II anode of step 1) is placed in the anode chamber as the anode, and the carbon cloth is used as the cathode; the Methanosarcina barkeri-polymerized nitrogen carbon suspension of step 2) is transferred to the cathode chamber of the microbial photoelectrochemical system to complete the assembly of the microbial photoelectrochemical system; a saturated sodium chloride calomel electrode is used as the reference electrode. When testing or using, the cathode and anode are connected through an external circuit (such as Figure 1 shown).

[0104] Table 1 is the method for preparing the culture medium of Methanosarcina barkeri

[0105]

[0106] Note: *Each liter of trace element solution SL10 contains 50 mL of HCl (2 M), 2 g FeCl2·4H2O, 0.2 g ZnCl2, 0.1 g MnCl2·4H2O, 0.18 g H3BO3, 0.05 g CoCl2·6H2O, 6 mg CuCl2·2H2O, 72 mg NiCl2·6H2O, 108 mg Na2MoO4·2H2O, and the balance is water.

[0107] **Each liter of selenite solution contains 0.5 g NaOH, 3 mg Na2SeO3·5H2O, 4 mg Na2WO4·2H2O, and the balance is water.

[0108] ***Each liter of vitamin solution contains 0.04g para-aminobenzoic acid, 0.01g D-biotin, 0.01g α-lipoic acid, 0.1g D-calcium pantothenate, 0.1g vitamin B6, 0.03g folic acid, 0.05g niacin, 0.05g riboflavin, 0.01g vitamin B1, 0.05g vitamin B 12 , the balance is water.

[0109] 4) Performance test of microbial photoelectrochemical system

[0110] Under the condition of constant temperature of 37±2℃, the LED full spectrum lamp (wavelength: 380nm~780nm, 1.0mW / cm 2 ) illuminated the microbial photoelectrochemical system to achieve CO2 reduction and methane production. The anode and cathode were connected to a potentiometer (CHI 1000C, TX, USA) via an external circuit to measure and record the current over time. The resulting methane production data was detected using a gas chromatograph (Agilent 7890A).

[0111] Comparative Example 1

[0112] This comparative example provides a microbial photoelectrochemical system, which differs from Example 1 in that: in step 2), no polymeric nitrogen dioxide is added when Methanosarcina barkeri grows to the logarithmic phase.

[0113] Comparative Example 2

[0114] This comparative example provides a microbial photoelectrochemical system, which differs from Example 1 in that: in step 1), no photosystem II is added to the anode.

[0115] Comparative Example 3

[0116] This comparative example provides a microbial photoelectrochemical system, which differs from Example 1 in that in step 1), no anthocyanin is added to the anode.

[0117] Result Analysis

[0118] from Figure 2 As can be seen, the microbial photoelectrochemical system of Example 1, using anthocyanin-photosystem II as the anode and a hybrid of Methanosarcina barkeri and polymeric nitrogen carbonate as the cathode, achieved the best results, with a maximum methane production of 45.96 ± 2.35 μmol. The methane production in Comparative Examples 1-3 was approximately 39.65%, 51.62%, and 26.49% of that in Example 1, respectively.

[0119] It was further confirmed that the main absorption wavelengths of photosystem II in the microbial photoelectrochemical system of Example 1 were mainly 400-450 nm and 650-700 nm, while the absorption wavelength of anthocyanins was mainly 450-575 nm. Combined with the short-wave absorption of polynitrogen carbide (<395 nm), full-spectrum absorption was achieved, thereby improving light utilization efficiency. At the same time, the polynitrogen carbide added to the cathode could also store excess photogenerated electrons, thereby improving the utilization efficiency of photogenerated electrons and further improving methane production performance.

[0120] Example 2

[0121] This example provides a microbial photoelectrochemical system, which differs from Example 1 in that the Methanosarcina barkeri in step 2) is replaced with Moorella thermoacetica, and the polymeric nitrogen nitride in the hybrid within the cathode chamber is replaced with phosphorus quantum dots. The resulting microbial photoelectrochemical system can produce acetic acid by reducing CO2 under illumination.

[0122] Specifically, the method for constructing the microbial photoelectrochemical system of this embodiment includes the following steps:

[0123] 1) Preparation of anthocyanin-photosystem II anode

[0124] Same as Example 1.

[0125] 2) Preparation of Mooreella thermoacetica-phosphorus quantum dot hybrids

[0126] Moorella thermoacetica was inoculated into a growth medium with a pH of 7.3 (formula as shown in Table 2) at a volume ratio of 10%, and cultured at a constant temperature of 58±2°C for 36 hours. Moorella thermoacetica was purchased from the American Type Culture Collection (ATCC39073). When Moorella thermoacetica grew to the logarithmic phase, 1 mg / mL phosphorus quantum dots were added. The mixture was placed in an incubator and cultured in the dark for 24 hours to form a Moorella thermoacetica-phosphorus quantum dot hybrid. After 24 hours, it was centrifuged at 4000 rpm for 5 minutes, washed with saline 3 times, and finally the bacterial solution was diluted with saline to obtain the OD value. 600 The value was changed to between 0.2 and 0.3, and the Moorellathermoacetica-phosphorus quantum dot suspension was transferred to the cathode of the microbial photoelectrochemical system.

[0127] 3) Assembling microbial photoelectrochemical systems

[0128] Same as Example 1.

[0129] Table 2 shows the culture medium preparation method for Moorella thermoacetica.

[0130]

[0131]

[0132] Note: 1 The concentration after mixing solutions A, B, and C.

[0133] 4) Performance test of microbial photoelectrochemical system

[0134] Under the condition of constant temperature of 37±2℃, the LED full spectrum lamp (wavelength: 380nm~780nm, 1.0mW / cm 2 ) The microbial photoelectrochemical system was subjected to intermittent illumination to achieve acetic acid production through CO2 reduction. Intermittent illumination was used. The anode and cathode were connected to a potentiometer (CHI 1000C, TX, USA) via an external circuit, and the acetic acid production data were monitored using a gas chromatograph (Agilent 7890A).

[0135] Comparative Example 4

[0136] This comparative example provides a microbial photoelectrochemical system, which differs from Example 2 in that: in step 2), phosphorus quantum dots are not added when Moorella thermoacetica grows to the late logarithmic stage.

[0137] Comparative Example 5

[0138] This comparative example provides a microbial photoelectrochemical system, which differs from Example 2 in that: in step 1), no photosystem II is added to the anode.

[0139] Comparative Example 6

[0140] This comparative example provides a microbial photoelectrochemical system, which differs from Example 2 in that: in step 1), no anthocyanin is added to the anode.

[0141] Results

[0142] from Figure 3As can be seen, the microbial photoelectrochemical system in Example 2, using anthocyanin-photosystem II as the anode and a hybrid of Mooreella thermoacetica and phosphorus quantum dots as the cathode, achieved a maximum acetic acid yield of 1.55 ± 0.17 mmol. In contrast, the acetic acid production in Comparative Examples 4-6 was only 75.21%, 82.57%, and 59.26% of that in Example 2, respectively.

[0143] Example 3

[0144] This embodiment provides a microbial photoelectrochemical system, which differs from Example 1 in that the anthocyanin-photosystem II anode in the anode chamber is replaced with a photosystem I-lycopene-lutein electrode, and the polymerized nitrogen carbon in the hybrid in the cathode chamber is replaced with sulfur quantum dots.

[0145] 1) Preparation of Photosystem I-Lycopene-Lutein Anode

[0146] The anode substrate electrode was immersed in a lycopene solution with a concentration of about 5%, immersed for 24 hours and dried at 4°C in the dark to obtain a lycopene-modified anode. The lycopene-modified anode was immersed in a lutein solution with a concentration of about 5%, immersed for 24 hours and dried at 4°C in the dark to obtain a lycopene-lutein-modified anode. Then, the photosystem I (20 μL / cm 2 ) and redox polymer P Os A mixture of 10 mg / mL of lycopene and lutein was added dropwise to the lycopene-lutein modified anode and dried in the dark at room temperature for 30 minutes to prepare the photosystem I-lycopene-lutein anode. The electrode was rinsed before use to remove loose surface matter.

[0147] 2) Preparation of Methanosarcina barkeri-sulfur quantum dot hybrids

[0148] Methanosarcina barkeri was inoculated into an acetic acid medium with a pH of 6.9 (see Table 1 for the formula) at a volume ratio of 20% and cultured at a constant temperature of 37±2°C. When Methanosarcina barkeri grew to the logarithmic phase, 1 mg / mL sulfur quantum dots were added and the cells were cultured in an incubator in the dark for 24 hours to form a Methanosarcina barkeri-sulfur quantum dot hybrid. After 24 hours, the cells were centrifuged at 7500 rpm for 6 minutes and washed three times with saline. The bacterial solution was finally diluted with saline to obtain the OD value. 600 value to 0.3.

[0149] 3) Assembling microbial photoelectrochemical systems

[0150] Same as Example 1.

[0151] Comparative Example 7

[0152] This comparative example provides a microbial photoelectrochemical system, which differs from Example 3 in that in step 2), sulfur quantum dots are not added when Methanosarcina barkeri grows to the late logarithmic stage.

[0153] Comparative Example 8

[0154] This comparative example provides a microbial photoelectrochemical system, which differs from Example 3 in that: in step 2), no lycopene is added to the anode.

[0155] Comparative Example 9

[0156] This comparative example provides a microbial photoelectrochemical system, which differs from Example 3 in that: in step 2), no lutein is added to the anode.

[0157] Results

[0158] from Figure 4 It can be seen that using the photosystem I-lycopene-lutein anode, the photosystem I-lutein anode, and the photosystem I-lycopene anode as the anode of the microbial photoelectrochemical system all produced methane. Among them, the microbial photoelectrochemical system using the photosystem I-lycopene-lutein anode and the hybrid of Methanosarcina barkeri and sulfur quantum dots as the cathode performed the best, with a maximum methane yield of 35.95±2.36 μmol. The methane production in Comparative Examples 7-9 was approximately 60.33%, 70.18%, and 53.46% of that in Example 3, respectively.

[0159] Example 4

[0160] This embodiment provides a microbial photoelectrochemical system, which differs from Example 1 in that the PBS in the anode chamber of step 3) is replaced with domestic sewage. The assembled microbial photoelectrochemical system then achieves CO2 reduction and methane production under light.

[0161] Comparative Example 10

[0162] This comparative example provides a microbial photoelectrochemical system, which differs from Example 4 in that: in step 1), no photosystem II is added to the anode.

[0163] Comparative Example 11

[0164] This comparative example provides a microbial photoelectrochemical system, which differs from Example 4 in that in step 1), no anthocyanin is added to the anode.

[0165] Results

[0166] from Figure 5 It can be seen that while the anthocyanin-photosystem II electrode, anthocyanin electrode, and Photosystem II electrode all achieved water purification as anodes in the microbial photoelectrochemical system, the anthocyanin-photosystem II electrode exhibited the best sterilization performance and purification effect, with a maximum methane production of 41.29.95 ± 2.12 μmol. The methane production in the two comparative examples was only 39.19% and 53.63% of that in Example 4.

[0167] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A microbial photoelectrochemical system, characterized in that: The microbial photoelectrochemical system includes an anode chamber and a cathode chamber, wherein the anode chamber is provided with an anode and a natural photosensitizer, and the cathode chamber is provided with a cathode and inoculated with a hybrid formed by combining microorganisms and non-metallic photosensitizers, wherein the natural photosensitizer in the anode chamber and the hybrid in the cathode chamber are deposited on the electrode or discretely distributed in the electrode chamber; The natural photosensitizer includes a first natural photosensitizer and a second natural photosensitizer. When the second natural photosensitizer is photosystem I, the first natural photosensitizer is lutein and lycopene; when the second natural photosensitizer is photosystem II, the first natural photosensitizer is anthocyanin. The non-metallic photosensitizer is selected from any one or more of polymeric nitrogen carbon, phosphorus quantum dots, and sulfur quantum dots; the addition range of the non-metallic photosensitizer is 0.1 mg / mL to 5 mg / mL; The cathode chamber is filled with a culture medium, and the culture medium is inoculated with a hybrid formed by combining the microorganism and the non-metallic photosensitizer; The method for constructing the hybrid comprises the following steps: inoculating microorganisms in a culture medium for culturing, adding a non-metallic photosensitizer when the culture reaches the logarithmic phase, and culturing in the dark to obtain the hybrid; In the hybrid, the microorganism and the non-metallic photosensitizer are combined with each other through electrostatic adsorption or surface self-deposition.

2. The microbial photoelectrochemical system according to claim 1, characterized in that: The microorganisms include any one or more of methanogens and acetogens.

3. The microbial photoelectrochemical system according to claim 1, characterized in that: The anode further includes a redox polymer attached to the surface of the electrode.

4. The microbial photoelectrochemical system according to claim 3, characterized in that: The redox polymer includes any one or more of poly(1-vinylimidazole-co-allylamine)-osmium(bipyridine) chloride, polybenzyl viologen, and polylysine benzoquinone.

5. The method for constructing a microbial photoelectrochemical system according to any one of claims 1 to 4, characterized in that: The method comprises the following steps: installing an anode and a natural photosensitizer in an anode chamber, installing a cathode in a cathode chamber and inoculating a hybrid formed by combining microorganisms and non-metallic photosensitizers to obtain the microbial photoelectrochemical system.

6. The method for using the microbial photoelectrochemical system according to any one of claims 1 to 4, characterized in that: The method comprises the step of irradiating the microbial photoelectrochemical system with light.

7. Use of the microbial photoelectrochemical system according to any one of claims 1 to 4 in water purification and / or synthesis of low molecular weight hydrocarbons.

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