Photocatalytic nanomaterial-microorganism hybrid and its preparation method and application

Abstract

The present invention discloses a photocatalytic nanomaterial-microorganism hybrid and its preparation method and application. The preparation method comprises the following steps: adding graphene oxide to a mixed solution containing a water-soluble divalent cadmium salt, thiourea and polyvinyl pyrrolidone, performing a hydrothermal reaction, then washing and vacuum drying to obtain a CdX / RGO material; culturing Shewanella under aerobic conditions to obtain a bacterial solution; dispersing the CdS / RGO material in an anaerobic buffer to obtain a buffer A; centrifuging the Shewanella bacterial solution and discarding the supernatant, then dispersing the precipitate cells obtained by centrifugation into a buffer A, mixing and stirring to obtain a CdS / RGO / MR-1 material. The present invention prepares a novel hybrid of photocatalytic-biological synergistic and efficient hydrogen production, which can realize the efficient transfer of photogenerated electrons from the extracellular to the intracellular hydrogenase to promote the efficiency of light energy utilization and hydrogen production.

Description

Technical Field

[0001] The present invention belongs to the technical field of green hydrogen energy production, and specifically relates to a hybrid of a photocatalyst, a conductive carbon material and a microorganism, and a preparation method and hydrogen production application thereof. Background Art

[0002] Solar hydrogen production is a clean energy production technology with great development potential. This technology usually uses photocatalysts to decompose water to produce hydrogen. However, due to the limitations of factors such as the light absorption range or photogenerated carrier recombination, the hydrogen production efficiency of existing photocatalysts is generally not high. In addition, hydrogen can also be produced by anaerobic decomposition of organic matter by microorganisms. This technology can be coupled with wastewater treatment processes to provide a new way for wastewater resource utilization. However, due to the existence of other competing organic matter decomposition metabolic pathways, there is a shortage of electron donors that can be effectively used for hydrogen production, which also limits its hydrogen production efficiency and long-term operation stability.

[0003] In recent years, researchers have attempted to construct inorganic-biological hybrid systems (IBSs) to achieve the coupling of photocatalysis and biological hydrogen production. This system can use the excellent light absorption properties of inorganic semiconductor materials to provide additional electrons for microbial metabolism, while using hydrogenases in microbial cells to catalyze the conversion of organic matter to produce hydrogen, so it is expected to achieve a continuous, stable, and low-cost hydrogen production process. However, since the photocatalytic material is located outside the cell and the microbial hydrogenase is located inside the cell, it is difficult for the photogenerated electrons to be effectively used by the microorganisms, which seriously limits the hydrogen production efficiency of IBSs. The key to breaking through this bottleneck is to increase the electron transfer rate at the interface between the material and the microbial cell. At present, researchers Lower, BH, et al. (APPLIED AND ENVIRONMENTAL MICROBIOLOGY, 2009. 75 (9): p. 2931-2935) have attempted to use soluble electron mediators such as dye molecules to construct electron channels between photocatalysts and intracellular hydrogenases, but the diffusion and mass transfer efficiency of such substances is low and they will continue to be lost. Some electron mediator molecules are also cytotoxic, which is not conducive to long-term efficient and stable operation. Therefore, there is an urgent need to develop inorganic-biological hybrids with stronger interfacial electron transfer capabilities to improve their solar hydrogen production efficiency. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present invention provides a hybrid of a photocatalyst, a conductive carbon material and a microorganism, and a preparation method and hydrogen production application thereof, which solves the problem of low interfacial electron transfer efficiency in the current photocatalytic composite system constructed by inorganic materials and microbial cells. The present invention utilizes microorganisms (such as Shewanella) with excellent transmembrane electron transfer ability and hydrogen production ability, and adds two-dimensional nanomaterials (such as graphene oxide) with good biocompatibility and conductivity as electron transfer media between inorganic photocatalytic materials (such as cadmium sulfide, CdS) and microbial cells, thereby forcing the combination of inorganic materials and biological cells and improving the interfacial electron transfer efficiency, thereby achieving efficient transfer of photogenerated electrons from extracellular to intracellular hydrogenase, so as to promote light energy utilization efficiency and hydrogen production efficiency.

[0005] The technical solution of the present invention is:

[0006] The present invention relates to a method for preparing a photocatalytic nanomaterial-microorganism hybrid, comprising the following steps:

[0007] (1) Preparation of CdS / RGO

[0008] Graphene oxide (GO) is added to a mixed solution containing a water-soluble divalent cadmium salt, thiourea and polyvinyl pyrrolidone, and a hydrothermal reaction is carried out, followed by washing and vacuum drying to obtain a CdX / RGO material;

[0009] (2) Cultivation of Shewanella

[0010] Cultivating Shewanella under aerobic conditions to obtain a bacterial solution;

[0011] (3) Preparation of CdS / RGO / MR-1

[0012] The CdS / RGO material is dispersed in an anaerobic buffer to obtain a buffer A; the bacterial solution obtained in step (2) is centrifuged to discard the supernatant, and then the precipitate cells obtained by centrifugation are dispersed in the buffer A, mixed and stirred to obtain the CdS / RGO / MR-1 material.

[0013] Preferably, the water-soluble divalent cadmium salt is cadmium chloride.

[0014] Preferably, the concentration of the divalent cadmium salt is 90-100 mmol / L, the concentration of thiourea is 90-100 mmol / L, and the concentration of polyvinyl pyrrolidone is 10-12 mg / mL;

[0015] In step (1), graphene oxide is added in the form of an ethylene glycol solution of graphene oxide, the concentration of the ethylene glycol solution of graphene oxide is 0.4-0.6 mg / mL, and the mass of graphene oxide accounts for 0.5-0.9% of the mass of polyvinyl pyrrolidone.

[0016] Preferably, in step (1), the hydrothermal reaction temperature is 160-200°C, and the time is 12-20 hours; the vacuum drying temperature is 60-80°C, and the time is 6-12 hours.

[0017] Preferably, in step (2), the culture process of the bacterial solution is: Shewanella is pre-inoculated and initially cultured aerobically under aerobic conditions, and then 10-20 mL of the aerobic cultured bacterial solution is transferred to 100-200 mL of fresh culture solution and cultured aerobically again under the same conditions.

[0018] Preferably, the culture medium used in step (2) is LB (Luria-Bertani) medium, and more preferably, the LB medium contains the following ingredients: 5 g / L yeast extract, 10 g / L tryptone, and 10 g / L sodium chloride, and the pH value of the LB medium is 6.8-7.2;

[0019] The initial aerobic culture time is 11-13 hours, and the secondary aerobic culture time is also 11-13 hours.

[0020] Preferably, in step (3), the concentration of the CdS / RGO material in the buffer A is 0.025-0.1 g / L; when preparing the buffer A, the CdS / RGO material is dispersed in the anaerobic buffer by ultrasound, and the ultrasonic dispersion time is 40-60 min;

[0021] After the precipitate cells were obtained by centrifugation and transferred to buffer A, the OD600 value of Shewanella in the anaerobic buffer was 1-3, and the magnetic stirring time was 30-40 min.

[0022] Preferably, the anaerobic buffer used in step (3) is first subjected to aeration deoxygenation and sterilization treatment, wherein the aeration deoxygenation time is 30-40 minutes, the sterilization temperature is 121° C., and the sterilization time is 20 minutes;

[0023] The anaerobic buffer contains 50mmol / L hydroxyethylpiperazineethanesulfonic acid, 50mmol / L sodium chloride, 20mmol / L sodium lactate, 1mmol / L ascorbic acid, and the pH range is 6.8-7.2.

[0024] The invention also relates to a photocatalytic nano material-microorganism hybrid, which is prepared by the above preparation method.

[0025] The invention also relates to the application of photocatalytic nanomaterial-microorganism hybrid in solar hydrogen production.

[0026] The beneficial effects of the present invention are:

[0027] 1) The present invention utilizes microorganisms with excellent transmembrane electron transfer ability and hydrogen production ability, and adds two-dimensional nanomaterials with good biocompatibility and conductivity as electron transfer media between inorganic photocatalytic materials and microbial cells, thereby strengthening the combination of inorganic materials and biological cells and improving the efficiency of interfacial electron transfer, thereby achieving efficient transfer of photogenerated electrons from extracellular to intracellular hydrogenase, thereby promoting light energy utilization efficiency and hydrogen production efficiency;

[0028] 2) Compared with conventional IBSs, the novel IBSs constructed by the present invention can realize efficient collection of photoelectrons and rapid transmission between microbial cells; the CdS / RGO / MR-1 hybrid system constructed by the present invention has the advantages of high stability and high hydrogen production performance. The hydrogen production of the hybrid system in 12 hours is significantly greater than that of the CdS / MR-1 system and the MR-1 system, and the operation is simple, the preparation process is safe, and the cost is low;

[0029] 3) The IBSs with efficient electron transfer performance constructed by the present invention have broad application prospects in solar hydrogen production and other photocatalytic fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0031] Figure 1 SEM morphology image of CdS / RGO in Example 1;

[0032] Figure 2 : Figure A is the SEM image of CdS / RGO / MR-1 in Example 1; Figure B is the EDS-mapping image of C, O, Cd and S elements in the area framed by Figure A;

[0033] Figure 3 XRD patterns of CdS / RGO, CdS and RGO materials;

[0034] Figure 4 : Figure A is the C1s spectrum of graphene oxide GO; Figures B to D are the C1s, Cd3d, and S 2p spectra of CdS / RGO in Example 1, respectively;

[0035] Figure 5 Effects of bacteria concentration and material concentration on hydrogen production performance in Example 1;

[0036] Figure 6 Cumulative graph of hydrogen production of different hybrid systems in Example 1 and Comparative Examples 1-2;

[0037] Figure 7 Cumulative graph of hydrogen production of the experimental group under light and the control group under dark conditions;

[0038] Figure 8 XRD spectrum of CdS / RGO-MR-1 after the photocatalytic reaction in Example 1. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0040] The present invention provides a method for preparing a photocatalytic nanomaterial-microorganism hybrid, comprising the following steps:

[0041] (1) taking appropriate amounts of water-soluble divalent cadmium salt and thiourea) and polyvinylpyrrolidone (PVP) and dissolving them in ethylene glycol to form a homogeneous mixed solution; wherein the water-soluble divalent cadmium salt is preferably cadmium chloride, the concentration of the divalent cadmium salt is 90-100 mmol / L, the concentration of thiourea is 90-100 mmol / L, and the concentration of the polyvinylpyrrolidone is 10-12 mg / mL;

[0042] (2) adding an appropriate amount of graphene oxide to the mixed solution of step (1), hydrothermally reacting for a period of time (reaction temperature 160-200° C., time 12-20 h), repeatedly washing with water and ethanol and then vacuum drying (temperature 60-80° C., time 6-12 h) to prepare a CdS / RGO material, wherein the graphene oxide is added in the form of an ethylene glycol solution of graphene oxide, the concentration of the ethylene glycol solution of graphene oxide is 0.4-0.6 mg / mL, and the mass of the graphene oxide accounts for 0.5-0.9% of the mass of the polyvinyl pyrrolidone;

[0043] (3) pre-inoculating Shewanella with good activity and aerobically culturing for 11-13 hours under aerobic conditions, transferring 10-20 mL of the aerobic cultured bacterial solution to 100-200 mL of fresh culture solution and aerobically culturing again for 11-13 hours under the same conditions; wherein the culture solution used is LB (Luria-Bertani) medium, and more preferably, the LB medium contains the following ingredients: 5 g / L yeast extract, 10 g / L tryptone, and 10 g / L sodium chloride, and the pH value of the LB medium is 6.8-7.2;

[0044] (4) preparing an anaerobic reactor containing an anaerobic buffer medium, removing oxygen by aeration with an inert gas (argon), and sterilizing after aeration; the medium contains the following ingredients: 50 mmol / L hydroxyethylpiperazine ethanesulfonic acid, 50 mmol / L sodium chloride, 20 mmol / L sodium lactate, 1 mmol / L ascorbic acid, and the pH range is 6.8-7.2; the aeration time is 30-40 min, the sterilization temperature is 121° C., and the time is 20 min;

[0045] (5) taking an appropriate amount of the CdS / RGO material prepared in step (2) and adding it to the anaerobic reactor of step (4), and further uniformly dispersing it by ultrasound to obtain a buffer A, wherein the concentration of the CdS / RGO material in the buffer A is preferably 0.025-0.1 g / L, and more preferably 0.05 g / L;

[0046] (6) Take an appropriate amount of the cultured Shewanella broth in step (3), centrifuge and discard the supernatant, then wash the precipitate obtained by centrifugation with a buffered salt medium for 2-3 times and resuspend it, and then transfer it to the buffer A of step (5). The OD600 value of Shewanella in the anaerobic buffer is 1-3. The anaerobic reactor is further placed on a magnetic stirrer for mixing and stirring. The magnetic stirring time is 30-40 minutes to obtain a photocatalytic nanomaterial-microorganism hybrid system (CdS / RGO / MR-1 material).

[0047] Example 1

[0048] (1) Preparation of CdS / RGO: 3.5 mmol of cadmium chloride (CdCl 2 . 2.5H 2 O) and 3.5 mmol of thiourea (NH 2 CSNH 2 ) and 389 mg polyvinyl pyrrolidone (PVP) were dissolved in 35 mL ethylene glycol, and then graphene oxide (5 mL, 0.5 mg / mL graphene oxide ethylene glycol solution) was added, and ultrasonication formed a homogeneous solution. After hydrothermal reaction at 160 ° C for 12 h, centrifugation (10000 rpm, 10 min) was performed to obtain a yellow precipitate. After washing with water and ethanol for six times, it was vacuum dried at 80 ° C for 6 h to obtain CdS / RGO material.

[0049] (2) Cultivation of Shewanella: Select the strain Shewanella oneidensis MR-1; inoculate Shewanella into 50 mL of LB medium (containing 5 g / L yeast extract, 10 g / L tryptone and 10 g / L sodium chloride, pH = 7), and shake at 30°C (200 rpm) for 12 h to obtain a bacterial solution; transfer 20 mL of the bacterial solution to 200 mL of fresh LB medium at a volume ratio of 1:10, and continue to activate under the same conditions for 12 h to obtain a bacterial solution;

[0050] (3) Preparation of CdS / RGO / MR-1: 1.5 mg of CdS / RGO photocatalyst was dispersed by ultrasound in an anaerobic reactor containing 30 mL of anaerobic buffer (the anaerobic buffer contained 50 mmol / L hydroxyethylpiperazine ethanesulfonic acid, 50 mmol / L sodium chloride, 20 mmol / L sodium lactate, 1 mmol / L ascorbic acid, pH 7.0, and the anaerobic buffer was aerated with inert gas (argon) to remove oxygen and sterilized after aeration. The aeration time was 30-40 min, the sterilization temperature was 121°C, and the time was 20 min) to obtain buffer A; the bacterial solution obtained in step (2) was collected by centrifugation, washed twice with anaerobic buffer and resuspended, and the bacterial suspension was transferred to buffer A. The OD600 value of Shewanella in the anaerobic buffer was 1. The anaerobic reactor was stirred on a magnetic stirrer for 30 min to obtain a photocatalytic nanomaterial-microorganism hybrid system (CdS / RGO / MR-1 material);

[0051] (4) Photocatalytic hydrogen production: The CdS / RGO / MR-1 mixed solution obtained in step (3) was irradiated with light, and the accumulated hydrogen content in the gas phase was detected every 4 h using a gas chromatograph (GC-9790).

[0052] Comparative Example 1

[0053] This embodiment also provides a method for synthesizing pure CdS

[0054] The preparation process of CdS / RGO is basically the same as that of step (1) of Example 1, except that the dosage of PVP is 0 g and the dosage of graphene oxide is also 0 mg. The CdS material prepared in this comparative example 1 is characterized by XRD.

[0055] Shewanella was cultured according to step (2) in Example 1, and then the CdS / RGO material in step (3) of Example 1 was replaced with the CdS material in this comparative example 1 to prepare a CdS / MR-1 material, and the photocatalytic hydrogen production performance of the CdS / MR-1 mixed solution was tested.

[0056] Comparative Example 2

[0057] This embodiment also provides a method for synthesizing pure RGO

[0058] The preparation process of CdS / RGO is basically the same as that of step (1) of Example 1, except that only 40 mg of graphene oxide is dissolved in 20 mL of ethylene glycol, and then a hydrothermal reaction is performed. The RGO material prepared in this comparative example 2 is characterized by XRD.

[0059] Shewanella was cultured according to step (2) in Example 1, and then the CdS / RGO material in step (3) of Example 1 was replaced with the RGO material in this comparative example 2 to prepare the RGO / MR-1 material, and the photocatalytic hydrogen production performance of the RGO / MR-1 mixed solution was tested.

[0060] The performance index test of the CdS / RGO / MR-1 inorganic biological hybrid system prepared in Example 1

[0061] (1) Materials and bacterial SEM characterization sample preparation

[0062] Take an appropriate amount of the CdS / RGO material synthesized in step (1) of Example 1, add 1 mL of anhydrous ethanol, sonicate for 80 to 90 min, and drop it on a silicon wafer for scanning electron microscopy characterization.

[0063] Take 1 mL of the solution of the mixture in the anaerobic reactor in step (3) of Example 1, centrifuge at 5000g for 5 minutes, discard the supernatant, rinse twice with PBS, add 1 mL of 2.5% glutaraldehyde and fix for more than 4 hours. Dehydrate with ethanol of concentration gradient (30%, 50%, 70%, 80%, 95%, 100%), remove the supernatant after centrifugation, resuspend with 1 mL of anhydrous ethanol, and drop the resulting solution on a silicon wafer for scanning electron microscopy characterization.

[0064] Figure 1 This is the SEM image of the CdS / RGO photocatalytic material synthesized in Example 1. It can be seen from the figure that CdS is evenly distributed on RGO and RGO wraps CdS. Figure 2 : The SEM image of CdS / RGO / MR-1 synthesized in Example 1 and the EDS-mapping images of C, O, Cd and S elements. It can be seen from the figure that RGO wraps CdS and then covers the bacteria.

[0065] (2) XRD characterization sample preparation

[0066] Take an appropriate amount of the CdS / RGO material synthesized in step (1) of Example 1 and the materials synthesized in Comparative Examples 1 and 2 for X-ray diffraction analysis and characterization. Figure 3The XRD patterns of various materials are compared with the standard card (#77-2306), indicating that the phase of the nanomaterial synthesized in Comparative Example 1 is CdS; and the peak of RGO does not appear in the spectrum of CdS / RGO, which may be due to the small amount of RGO added and poor crystallinity.

[0067] (3) XPS characterization sample preparation

[0068] Take an appropriate amount of CdS / RGO synthesized in step (1) of Example 1 for XPS characterization. Figure 4 The XPS spectrum of the material prepared in Example 1. By analyzing the peak of carbon in the CdS / RGO composite material, it was found that the percentage of CO and C=O in the composite material decreased rapidly, thus proving the synthesis of RGO; the XPS spectrum of Cd 3d showed two characteristic peaks at 403.9eV and 410.7eV, confirming that the Cd in CdS behaved as Cd 2+ ;S2p 1 / 2 and S2p 3 / 2 orbitals were observed at 161.2 eV and 162.8 eV, respectively, indicating that S 2- The presence of; combined with the results of SEM and XRD, it is proved that the synthesized material is CdS / RGO.

[0069] (4) Determination of optimal hydrogen production conditions

[0070] Referring to the mixed solution obtained in step (3) of Example 1, different concentration gradients of bacteria (OD600=1, 2, 3) and materials (0.025, 0.05, 0.1 g / L) were set, the mixed solution was illuminated, and the cumulative hydrogen content in the gas phase was detected every 4 hours using a gas chromatograph (GC-9790). Figure 5 To evaluate the determination of the optimal hydrogen production conditions, it can be seen from the figure that the optimal hydrogen production conditions are bacterial concentration OD600=1 and material concentration of 0.05g / L.

[0071] (5) Evaluation of the photocatalytic hydrogen production performance of inorganic-biohybrids

[0072] The CdS / RGO / MR-1 mixed solution obtained in step (3) of Example 1, the CdS / MR-1 mixed solution obtained in Comparative Example 1, and the RGO / MR-1 mixed solution obtained in Comparative Example 2 were tested for photocatalytic hydrogen production. Figure 6 It is the accumulated hydrogen content of the three experimental groups in different time periods. As can be seen from the figure, the composite catalyst described in the embodiment of the present invention has a high hydrogen production efficiency, and the accumulated hydrogen content in 12 hours is 12 times the sum of the accumulated hydrogen content of the CdS / MR-1 group and the RGO / MR-1 group.

[0073] (6) Hydrogen production performance test of experimental group and control group

[0074] The CdS / RGO material (without bacteria) obtained in step (1) of Example 1, the bacteria (without material) obtained in step (2), and the CdS / RGO / MR-1 mixed solution obtained in step (3) were taken and hydrogen production tests were carried out in the environment with light (experimental group) and without light (control group), respectively.

[0075] Figure 7 : The hydrogen content accumulated in the six experimental groups and the control group in different time periods. It can be seen from the figure that under light conditions, the hydrogen content accumulated in 12 hours by CdS / RGO / MR-1 described in Example 1 of the present invention is 22 times that of the pure bacteria group (MR-1).

[0076] (7) XRD characterization sample preparation after hydrogen production

[0077] Take the CdS / RGO / MR-1 mixed solution after photocatalytic hydrogen production (cumulative time of 24 hours) in step (4) of Example 1, centrifuge at 7000rpm for 10 minutes, discard the supernatant, and place the collected precipitate in a vacuum drying oven at 80°C for 6 hours; use an agate mortar to grind the dried solid into a uniform powder, and take an appropriate amount of the powder for X-ray diffraction analysis and characterization. Figure 8 As shown, CdS / RGO represents the CdS / RGO material synthesized in step (1) of Example 1. It can be seen from the XRD diagram that the peak of CdS / RGO material exists in CdS / RGO-MR-1 after the reaction, and the peak position has almost no change. As for the wider peak at 2θ=20°, it is the peak of bacteria. The presence of bacteria reduces the peak intensity.

[0078] (8) ICP-AES test of Cd element concentration after hydrogen production

[0079] Take the solution before and after the photocatalytic hydrogen production in step (4) of Example 1, centrifuge at 12000rpm for 5min, discard the precipitate and keep the supernatant. Digest the obtained supernatant, add 4mL nitric acid and boil at high temperature, then add 1mL perchloric acid, and digestion is completed when thick white smoke comes out of the digestion tube. The volume of the solution is fixed to 5mL, and the Cd element concentration in the solution is measured by ICP-AES. It is calculated that the Cd element dissolution concentration after the photocatalytic reaction is 0.045mg / L, and the dissolution rate is 0.09%. Combined with the XRD characterization results after photocatalytic hydrogen production, it is shown that the inorganic biological hybrid system has good stability during the photocatalytic reaction.

[0080] It should be understood that the above specific embodiments of the present invention are only used to illustrate or explain the principles of the present invention, and do not constitute a limitation of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the appended claims, or the equivalent forms of such scope and boundaries.

Claims

1. Application of a photocatalytic nanomaterial-microorganism hybrid in solar hydrogen production, characterized in that: The preparation method of the photocatalytic nanomaterial-microorganism hybrid comprises the following steps: (1) Preparation of CdS / RGO The graphene oxide is added to a mixed solution containing a water-soluble divalent cadmium salt, thiourea and polyvinyl pyrrolidone, and a hydrothermal reaction is carried out at a temperature of 160-200° C. The graphene oxide is then washed and vacuum dried to obtain a CdS / RGO material. The mixed solution containing a water-soluble divalent cadmium salt, thiourea and polyvinyl pyrrolidone uses ethylene glycol as a solvent, the concentration of the divalent cadmium salt is 90-100 mmol / L, the concentration of the thiourea is 90-100 mmol / L, and the concentration of the polyvinyl pyrrolidone is 10-12 mg / mL; in step (1), the graphene oxide is added in the form of an ethylene glycol solution of graphene oxide, the concentration of the ethylene glycol solution of graphene oxide is 0.4-0.6 mg / mL, and the mass of the graphene oxide accounts for 0.5-0.9% of the mass of the polyvinyl pyrrolidone; (2) Cultivation of Shewanella Under aerobic conditions, Shewanella Oneida MR-1 was cultured to obtain a bacterial liquid; (3) Preparation of CdS / RGO / MR-1 The CdS / RGO material is dispersed in an anaerobic buffer to obtain a buffer A; the bacterial solution obtained in step (2) is centrifuged to discard the supernatant, and then the precipitate cells obtained by centrifugation are dispersed in the buffer A, and the mixture is mixed by magnetic stirring to obtain a CdS / RGO / MR-1 material, i.e., a photocatalytic nanomaterial-microorganism hybrid.

2. The use according to claim 1, characterized in that: The water-soluble divalent cadmium salt is cadmium chloride.

3. The use according to claim 1, characterized in that: In step (1), the hydrothermal reaction time is 12-20 hours; the vacuum drying temperature is 60-80°C and the time is 6-12 hours.

4. The use according to claim 1, characterized in that: In step (2), the culture process of the bacterial solution is as follows: Shewanella MR-1 is inoculated in advance and initially cultured aerobically under aerobic conditions, and then 10-20 mL of the aerobic cultured bacterial solution is transferred to 100-200 mL of fresh culture solution and cultured again aerobically under the same conditions.

5. The use according to claim 4, characterized in that: The culture medium used in step (2) is LB medium; the time of the first aerobic culture is 11-13 hours, and the time of the second aerobic culture is also 11-13 hours.

6. The use according to claim 1, characterized in that: In step (3), the concentration of CdS / RGO material in buffer A is 0.025-0.1 g / L; after the precipitate cells are obtained by centrifugation and transferred to buffer A, the OD600 value of Shewanella MR-1 in the anaerobic buffer is 1-3, and the magnetic stirring time is 30-40 min.

7. The use according to claim 1, characterized in that: The anaerobic buffer used in step (3) is first subjected to aeration, deoxygenation and sterilization treatment.

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