A quantum dot silver sulfide ag2s-qd hybrid photo-catalyst of onydia lake shivae and a synthesis method thereof

Abstract

The application belongs to the technical field of hydrogen energy production, and discloses a quantum dot silver sulfide Ag2S-QD hybrid Shewanella oneidensis MR-1 photocatalyst and a synthesis method thereof. When the quantum dot silver sulfide Ag2S-QD hybrid Shewanella oneidensis MR-1 photocatalyst prepared by the method is used as a photocatalytic hydrolysis hydrogen production catalytic material, the quantum dot silver sulfide Ag2S-QD particles in-situ synthesized in the bacterial body can increase the light source absorption frequency band and improve the photoelectron output efficiency, which is conducive to enhancing the photocatalytic hydrolysis hydrogen production reaction capacity of the Shewanella oneidensis MR-1 cell. The quantum dot silver sulfide Ag2S-QD hybrid Shewanella oneidensis MR-1 has good hydrogen production efficiency and glucose-containing organic wastewater degradation capacity during work, has comprehensive benefits of environmental waste treatment and renewable energy development, and has a huge application prospect.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen energy production technology, and more specifically, relates to a photocatalyst of quantum dot silver sulfide Ag2S-QD hybrid Lake Oneida Shewanella and its synthesis method. Background Technology

[0002] Silver sulfide (Ag₂S), an important group II-VI semiconductor material, possesses excellent photoelectric properties and is widely used in optoelectronic devices, sensors, and solar cells. Traditional chemical synthesis methods typically require high temperatures and pressures and use toxic chemical reagents, increasing operational complexity and causing environmental pollution. Therefore, developing a green, low-energy synthesis method has become a research focus. Numerous studies have reported different methods for Ag₂S synthesis, including chemical deposition, hydrothermal methods, and solvothermal methods. For example, some studies have successfully synthesized high-purity Ag₂S nanoparticles by reacting hydrogen sulfide gas (H₂S) with silver salts. Furthermore, researchers have synthesized silver sulfide particles of different morphologies and sizes by reacting silver ions with a sulfur source using solution methods. These synthesis methods allow for precise control of the structure and size of nanomaterials, thereby optimizing their photoelectric properties.

[0003] However, these traditional methods typically require high-temperature or high-pressure operating conditions and also suffer from problems such as chemical reagent contamination. To mitigate these drawbacks, in recent years, an increasing number of studies have begun to explore methods for synthesizing nanomaterials through microorganisms. For example, Sun et al. developed a whole-cell biohybrid catalyst based on surface display technology. By fusing the outer membrane protein OmpA with a silver-binding peptide, they displayed specific silver-binding sites on the surface of engineered *E. coli*, and then utilized the cell's own cysteine ​​metabolism to provide a sulfur source, successfully synthesizing Ag2S quantum dots in situ on the cell surface, thus constructing an *E. coli*-Ag2S QD biohybrid system.

[0004] Furthermore, by integrating semiconductor nanomaterials with cells, it is possible to transcend the limitations of their natural metabolism and endow cells with entirely new catalytic functions. This provides a new paradigm for the conversion of solar energy into chemical energy through rational biohybridization design. Summary of the Invention

[0005] Based on existing technologies, this invention first provides a new method for synthesizing metal sulfides (Ag2S) using Shewanella bacteria under sulfur source (Na2S2O3, Na2S) and metal ion source (AgNO3) conditions, thereby improving the efficiency of photocatalytic hydrogen production and providing a new solution for the utilization of green biological hydrogen energy.

[0006] A second objective of this invention is to provide a hydrogen production system prepared by the above method.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] A method for preparing a photocatalyst of quantum dot silver sulfide Ag2S-QD hybrid Lake Oneida Shewanella includes the following steps:

[0009] S1. Using Shewanella oneidensis MR-1 strain from Lake Oneida as a microbial vector, the bacteria were routinely cultured and activated;

[0010] S2: After centrifugation and washing, the bacterial precipitate is suspended in an aqueous culture medium containing silver nitrate and sulfur source of a specific concentration, and mixed to obtain a quantum dot incubation solution.

[0011] S3: After centrifuging the quantum dot incubation solution in S2 to remove the supernatant, retain and wash the bacterial precipitate to obtain the photocatalyst of quantum dot silver sulfide Ag2S-QD hybrid Oneida Lake Shewanella.

[0012] Preferably, in the preparation method described above, the concentration of silver nitrate in step S2 is 0.1-1.0 mM, and the sulfur source is sodium thiosulfate (Na2S2O3) with a concentration of 1 mM.

[0013] Preferably, in the preparation method described above, the *Shewanella oneda* bacteria described in S1 are cultured in a medium at 30°C, preferably a TSB medium, in a constant temperature shaker until OD (dose dissipation). 600 The specific concentration is 2.5-2.7.

[0014] Preferably, in the preparation method described above, the pH value of the quantum dot incubation solution in S2 is 7.0-7.5.

[0015] The present invention also provides the application of the photocatalyst obtained by the method in photocatalytic hydrogen production.

[0016] Specifically, the aforementioned photocatalyst can be used as a photocatalytic active site material in an oxygen-free photocatalytic water splitting hydrogen production device.

[0017] When *Shewanella yunnanensis* from Lake Oneida, as described in this invention, comes into contact with silver ions and thiosulfate ions, its own heavy metal detoxification biomineralization mechanism is triggered. Thiosulfate ions are reduced to sulfide ions by thiosulfate reductase via the sulfur metabolism pathway and then combine with silver ions inside the bacterial cell to form nano-diameter quantum dot silver sulfide Ag2S-QD. Sodium thiosulfate is chosen because of its functionalization to generate S... 2- The rate of ion synthesis depends on the activity of biological enzymes and is kinetically controlled by biological metabolism. This avoids problems such as excessive toxicity caused by direct use of sulfur ions, excessively fast synthesis rate of Ag2S quantum dots, extracellular synthesis, and random deposition sites.

[0018] When the quantum dot silver sulfide Ag2S-QD hybrid Shewanella Oneida photocatalyst is exposed to light, the quantum dots absorb light energy and convert it into photogenerated electrons. These electrons are then transported through the MtrCAB pigment on the cell membrane of Shewanella Oneida to hydrogenases enriched in the periplasm, promoting the catalytic synthesis of hydrogen and significantly improving the photocatalytic hydrogen production performance.

[0019] The present invention also provides the application of the photocatalyst obtained by the method in the degradation of organic wastewater.

[0020] Preferably, the above application involves centrifuging the quantum dot silver sulfide Ag2S-QD hybrid Shewanella from Lake Oneda, dispersing the precipitate into the reaction solution, sealing and evacuating, stirring, and reacting under certain conditions to produce hydrogen / or degrade organic wastewater.

[0021] More preferably, in the above applications, the reaction solution or organic wastewater is composed of 1X / L PBS buffer solution, 5mmol / L glucose and 20mmol / L cysteine.

[0022] More preferably, the above-mentioned photocatalytic hydrogen production method using the quantum dot silver sulfide Ag2S-QD Lake Oneida Shewanella hybrid includes the following steps:

[0023] The quantum dot silver sulfide Ag2S-QD Oneida Lake Shewanella hybrid was centrifuged at 6000 rpm for 5 min. The precipitate was then dispersed in a photoreaction container (Beijing Bofeilai) containing 80 mL of reaction solution. A micro-gas reaction evaluation system (μgas1000, Beijing Bofeilai) was used to seal the container under vacuum. The hydrogen production temperature was 28-37℃ with continuous stirring. Under the illumination of a xenon lamp (Microsolar 300, λ> 420 nm, Beijing Bofeilai) with an added light shield, the reaction time was 4-60 h. Hydrogen was produced. The hydrogen content in the gas sample produced per hour was analyzed by gas chromatography (GC9790, Fuli).

[0024] The preferred reaction temperature is 30℃, the preferred stirring rate is 380 rpm, and the preferred xenon lamp power is 2000 W / m. 2 A filter is used to provide incident light with a wavelength greater than 420nm to excite photogenerated electrons in the quantum dot silver sulfide.

[0025] The metal sulfide microbial hybrid dispersed in anaerobic culture medium OD 600 The preferred value is 2.5.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] This invention provides a simple, rapid, and mildly synthesized engineered quantum dot silver sulfide Ag2S-QD hybrid Shewanella Oneida from Lake Oneida as a photocatalyst, along with its preparation method and its application in anaerobic photocatalytic biological hydrolysis for hydrogen production. When used as a photocatalytic hydrogen production catalyst, the in-situ synthesized quantum dot silver sulfide Ag2S-QD particles within the bacteria increase the light source absorption frequency and improve photoelectron production efficiency, thus enhancing the photocatalytic hydrogen production capability of Shewanella Oneida cells. The quantum dot silver sulfide Ag2S-QD hybrid Shewanella Oneida exhibits good hydrogen production efficiency and glucose-containing organic wastewater degradation capability, demonstrating comprehensive benefits in environmental waste management and renewable energy development, with significant application prospects. Attached Figure Description

[0028] Figure 1 This is a scanning electron microscope image of the nano-silver sulfide-Shewanella hybrid prepared in Example 1 of this application;

[0029] Figure 2 This is a transmission electron microscope image of the nano-silver sulfide-Shewanella hybrid prepared in Example 1 of this application;

[0030] Figure 3 X-ray diffraction pattern of nano-silver sulfide prepared in Example 1 of this application and its comparison with standard pattern PDF#14-0072;

[0031] Figure 4 The image shows a confocal image of the nano-silver sulfide-Shewanella hybrid prepared in Example 1 of this application after a hydrogen production process; the left image is the overall image, the middle image is the live bacteria image, the right image is the dead bacteria image, and the left image is a superposition of the middle and right images.

[0032] Figure 5 This is a comparison chart showing the hydrogen production capacity of the nano-silver sulfide-Shewanella hybrid prepared in Example 1 of this application under different metal ion incubation concentrations. Detailed Implementation

[0033] To better illustrate the purpose, technical solution, and advantages of this invention, the invention will be further described below with reference to specific drawings and embodiments. Unless otherwise specified, the experimental methods used in the embodiments are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0034] Shewanella was first cultured aerobicly for 24 hours under aerobic conditions (using TSB medium), and the OD of the bacterial culture was obtained. 600The value is 2.5-2.7. Take 10 ml of bacterial culture and resuspend it in 100 ml of TSB medium, add 0.1-1.0 mM AgNO3 and 1.0 mM Na2S2O3, and incubate at 30℃ and 180 rpm for 48 h to form a hybrid, which is the photocatalyst.

[0035] The TSB culture medium is a standard formula used in this industry. Specifically, accurately weigh 17.0 g tryptone, 3.0 g soybean peptone, 5.0 g sodium chloride, 2.5 g dipotassium hydrogen phosphate, and 2.5 g glucose into 950 mL of deionized water using an analytical balance. Stir with a glass rod until completely dissolved. Adjust the pH to 7.3 ± 0.2 with hydrochloric acid or sodium hydroxide. Make up the volume to 1000 mL with deionized water. Dispense into Erlenmeyer flasks, ensuring the liquid level in each flask does not exceed 20% of the flask's volume. Autoclave at 121°C for 15-20 minutes.

[0036] A photocatalytic hydrogen production method includes the following steps: A quantum dot silver sulfide Ag2S-QD Oneida Lake Shewanella hybrid is centrifuged at 6000 rpm for 5 min. The precipitate is then dispersed into a photoreaction container (Beijing Bofeilai) containing 80 mL of reaction solution. A micro-gas reaction evaluation system (μgas1000, Beijing Bofeilai) is used for vacuum sealing. The hydrogen production temperature is 28-37℃ with continuous stirring. Under illumination from a xenon lamp (Microsolar 300, λ > 420 nm, Beijing Bofeilai) with an added light shield, the reaction time is 4-60 h. Hydrogen is produced, and the product is analyzed by gas chromatography (GC9790, Fuli) to determine the hydrogen content in the hourly gas sample.

[0037] The preferred reaction temperature is 30℃, the preferred stirring rate is 380 rpm, and the preferred xenon lamp power is 2000 W / m. 2 A filter is used to provide incident light with a wavelength greater than 420nm to excite photogenerated electrons in the quantum dot silver sulfide.

[0038] The metal sulfide microbial hybrid dispersed in anaerobic culture medium OD 600 The preferred value is 2.5.

[0039] Example 1

[0040] Shewanella was first cultured aerobicly for 24 hours under aerobic conditions (using TSB medium), and the OD of the bacterial culture was obtained. 600The value was 2.5. 10 ml of bacterial culture was resuspended in 100 ml of TSB medium, and 0.1 mM AgNO3 and 1.0 mM Na2S2O3 were added. The mixture was incubated at 30°C and 180 rpm for 48 h on a shaker to form a heterozygote. Samples were taken for morphological and chemical composition analysis. Figure 1 As shown, scanning electron microscopy revealed that Shewanella bacteria exhibited good growth morphology; Figure 2 As shown, transmission electron microscopy reveals that black nanoparticles are uniformly dispersed within the cytoplasm of yeast cells; Figure 3 As shown, the diffraction pattern of the standard crystal of silver sulfide synthesized using an X-ray diffractometer is numbered PDF#14-0072, and it has a monoclinic argentite structure.

[0041] The heterozygous precipitate was then dispersed in a light reaction vessel containing 80 ml of reaction solution (1X / L PBS buffer, 5 mmol / L glucose, and 20 mmol / L cysteine) and irradiated for 24 h. The product was detected by gas chromatography, and the hydrogen production rate was 0.145 μmol / h. Figure 5 As shown; Figure 4 The laser confocal CLSM shown indicates that live bacteria are stained green and dead bacteria are stained red, and the bacteria show almost no death after incubation and hydrogen production.

[0042] Example 2

[0043] Shewanella was first cultured aerobicly for 24 hours under aerobic conditions (using TSB medium), and the OD of the bacterial culture was obtained. 600 The value is 2.4-2.7, preferably 2.5. 10 ml of bacterial culture was resuspended in 100 ml of TSB medium, and 1.0 mM MgNO3 and 1.0 mM Na2S2O3 were added. The mixture was incubated at 30°C and shaken at 180 rpm for 48 h to form a heterozygote. The heterozygote precipitate was then dispersed in a light reaction vessel containing 80 ml of reaction solution (1X / L PBS buffer, 5 mmol / L glucose, and 20 mmol / L cysteine) and irradiated for 24 h. The product was detected by gas chromatography, and the hydrogen production rate was 0.790 μmol / h. Figure 5 As shown in red.

Claims

1. A method for preparing a photocatalyst of quantum dot silver sulfide Ag2S-QD hybrid Lake Oneida Shewanella, characterized in that, Includes the following steps: S1. Using Shewanella oneidensis MR-1 strain from Lake Oneida as a microbial vector, the bacteria were routinely cultured and activated; S2: After centrifugation and washing, the bacterial precipitate is suspended in an aqueous culture medium containing silver nitrate and sulfur source of a specific concentration, and mixed to obtain a quantum dot incubation solution. S3: After centrifuging the quantum dot incubation solution in S2 to remove the supernatant, retain and wash the bacterial precipitate to obtain the photocatalyst of quantum dot silver sulfide Ag2S-QD hybrid Oneida Lake Shewanella.

2. The preparation method according to claim 1, characterized in that, The concentration of silver nitrate in S2 is 0.1-1.0 mM, and the sulfur source is sodium thiosulfate (Na2S2O3) with a concentration of 1 mM.

3. The preparation method according to claim 1, characterized in that, OD of Shewanella from Lake Oneida after routine culture and activation in S1 600 It is 2.5-2.

7.

4. The application of the photocatalyst obtained by the method according to any one of claims 1 to 3 in photocatalytic hydrogen production.

5. The application of the photocatalyst obtained by the method according to any one of claims 1 to 3 in the degradation of organic wastewater.

6. The application according to claim 4, characterized in that, After centrifuging the photocatalyst of quantum dot silver sulfide Ag2S-QD hybrid Lake Oneida Shewanella, the precipitate was dispersed in the reaction solution, sealed and vacuumed, stirred, and reacted to produce hydrogen under certain conditions.

7. The application according to claim 5, characterized in that, After centrifuging the photocatalyst of quantum dot silver sulfide Ag2S-QD hybrid Lake Oneida Shewanella, the precipitate was dispersed in the reaction solution, sealed and vacuumed, stirred, and the organic wastewater was degraded under certain conditions.

8. The application according to claim 6 or 7, characterized in that, The reaction solution consisted of 1X / L PBS buffer, 5 mmol / L glucose, and 20 mmol / L cysteine.

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