Preparation method and application of electrocatalyst for permeation of carbon quantum dots into escherichia coli
By infiltrating E. coli electrocatalysts with carbon quantum dots to improve electron transfer and cell metabolism, the efficiency and stability issues of precious metals and enzyme catalysts in microbial fuel cells were solved, achieving highly efficient electrocatalysis and degradation of organic wastewater.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-13
- Publication Date
- 2026-03-10
AI Technical Summary
Existing precious metal catalysts in microbial fuel cells suffer from low economic efficiency, poor stability, easy degradation of enzyme catalysts, and difficulty in effectively improving the efficiency of cathode oxygen reduction reaction in complex environments.
An electrocatalyst infused with carbon quantum dots in E. coli was used to improve the electron transfer capacity and cellular metabolic activity of E. coli, thereby enhancing the cathodic redox reaction performance.
This method improves the power generation efficiency and organic wastewater degradation capacity of microbial fuel cells, achieves efficient and stable electrocatalytic performance, and has a simple and environmentally friendly preparation method.
Smart Images
Figure CN121628784A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of biomaterials technology for air cathodes of microbial fuel cells, and relates to a method for preparing an electrocatalyst infiltrated with carbon quantum dots in Escherichia coli and its application. Background Technology
[0002] Microbial fuel cells (MFCs) utilize the metabolic activities of microorganisms to catalytically oxidize organic waste, converting chemical energy into electrical energy. This simultaneously achieves wastewater treatment and bio-power generation, realizing the dual goals of waste resource recovery and energy recycling. With multiple functions including degrading water pollutants and generating electricity, they are widely regarded as an important technology for producing green energy and controlling environmental pollution.
[0003] Enhancing the oxygen reduction reaction (ORR) in the cathode chamber is an effective strategy to improve MFC efficiency. Cathode catalysts are mainly classified into noble metal catalysts, non-noble metal catalysts, and enzyme catalysts. While noble metal catalysts such as Pt exhibit high catalytic activity, they suffer from low economic efficiency, poor renewability, and poor stability. In fact, the active sites of platinum group metal electrocatalysts are easily poisoned and deactivated by various anions, affecting their durability. Furthermore, they cannot degrade organic pollutants in the environment, making them unsuitable for use in the complex and harsh environments of MFC systems. Enzyme catalysts also suffer from key drawbacks such as easy degradation. Compared to the former two, microbial catalysts offer advantages such as low cost and availability, mild operating conditions, green renewability, and good resistance to environmental stress. Therefore, designing cathode ORR catalysts with higher catalytic activity, stronger stability, and lower cost is a research hotspot in MFC.
[0004] The development of MFC systems is similar to that of enzyme fuel cells, an electrochemical system that utilizes biocatalysts to catalyze electrochemical reactions at one or two electrodes. However, instead of specific redox enzymes, the catalyst material is modified with whole bacterial cells as biocatalysts. The basic working principle of an MFC relies on two redox half-reactions, typically occurring in two electrode chambers separated by a proton exchange membrane (PEM) and connected by external wires. The anode accepts electrons released from the respiration and metabolism of microbial cells, which flow through the external circuit to the cathode, where electrons are transferred to the electron acceptor, usually oxygen in most practical applications. Simultaneously, protons released from organic matter by microbial metabolism move from the anode to the cathode, thus generating electricity while removing organic waste. In this process, electrochemically active microorganisms catalyze the oxidation of organic substrates (fuels) at the anode, such as glucose, lactose, sucrose, xylose, and malic acid; the cathode typically undergoes a redox reaction (ORR) in the presence of a catalyst, including both biological and non-biological catalysts. To improve the performance of bioelectrocatalytic systems, the biocatalysts must be modified to enhance cellular metabolic activity and electron transport capacity, thereby increasing reaction efficiency.
[0005] Therefore, the performance of cathode ORR catalysis can be improved by rationally selecting and modifying existing catalysts or designing new catalysts to meet the operating requirements of MFC. Summary of the Invention
[0006] The technical problem solved by this invention is to provide a simple, rapid, and mild method for preparing carbon quantum dot-infiltrated Escherichia coli electrocatalysts.
[0007] Another objective of this invention is to provide the application of the aforementioned electrocatalyst in the preparation of air cathodes for microbial fuel cells. When the carbon quantum dot-infiltrated *E. coli* electrocatalyst prepared by the method provided by this invention is used as a catalytic material for the air cathode of an MFC, the carbon quantum dot infiltration into *E. coli* improves the electrocatalytic ORR reduction performance of *E. coli* through two pathways: First, the excellent conductivity of the carbon quantum dots themselves improves the electron transfer ability of *E. coli*, thereby increasing respiratory chain efficiency. Second, the carbon quantum dots can activate the cell's own metabolic activity, enhancing its ORR reduction activity. The combination of these two factors contributes to the excellent electrocatalytic ORR activity of the entire *E. coli* cell, resulting in both good power generation efficiency and the ability to degrade glucose-containing organic wastewater when assembled into a complete microbial fuel cell.
[0008] The objective of this application is achieved through the following technical solution:
[0009] A method for preparing an electrocatalyst infiltrating carbon quantum dots into Escherichia coli includes culturing biosafe Escherichia coli, obtaining a culture medium after culturing, centrifuging to obtain a bacterial precipitate, and then adding an aqueous solution of carbon quantum dots to a buffer solution of the bacterial precipitate for co-culturing.
[0010] Preferably, the carbon quantum dots are obtained by the following treatment: dissolving 100mg-500mg of riboflavin in 50-100ml of water, and then carrying out a hydrothermal reaction at a temperature of 160-180℃ for 18-30h.
[0011] Preferably, the co-cultivation time is 2 to 3 hours.
[0012] Preferably, the mass concentration of the aqueous solution of carbon quantum dots is 2-5 g / L; the volume of the buffer solution for bacterial precipitation is 20-30 ml; and the amount of aqueous solution of carbon quantum dots added is 10-100 μL.
[0013] This invention also protects the electrocatalyst obtained by the preparation method.
[0014] Furthermore, it protects the application of the electrocatalyst in the preparation of the cathode for a microbial fuel cell.
[0015] Furthermore, the electrocatalyst is suspended in LB liquid culture medium, and the carbon cloth electrode is placed in the liquid culture medium and incubated with bacteria to finally obtain a carbon cloth electrode, i.e., a cathode, infiltrated into the E. coli electrocatalyst biofilm with attached carbon quantum dots.
[0016] Furthermore, co-incubation was performed using LB liquid medium, the composition of which was 10 g / L. -1 Tryptone, 5g / L -1 Yeast extract and 5g L -1 Sodium chloride; the co-incubation time is 24 to 48 hours.
[0017] The present invention also protects a microbial fuel cell, comprising a microbial fuel cell cathode prepared from the electrocatalyst.
[0018] Preferably, the cathode liquid of the microbial fuel cell is a 20mM glucose solution, the anode is a carbon cloth electrode coated with commercial Pt / C, the anolyte is a 1M glucose solution, the two chambers are separated by a proton exchange membrane, the microbial fuel cell is placed in an incubator at 30~37℃, an external resistor is connected, oxygen is introduced into the cathode liquid, and nitrogen is introduced into the anolyte.
[0019] This invention also protects the application of the electrocatalyst in the preparation of the working electrode of a three-electrode half-cell. Preferably, in the three-electrode half-cell, the platinum sheet and the saturated silver / silver chloride electrode serve as the counter electrode and the reference electrode, respectively.
[0020] Compared with the prior art, the present invention has the following advantages:
[0021] The preparation method of this invention is simple, rapid and efficient, with mild reaction conditions, low cost and environmental friendliness. It is derived from plant polyphenols and has good biocompatibility. The carbon quantum dots have almost no effect on cell viability, self-replication and self-repair ability, and have broad application potential.
[0022] Carbon quantum dots, as small molecules, can easily pass through the cell membrane and enter the cell to modify individual cells. They can not only act as electron transport carriers, but also improve cell metabolic activity through design, thereby improving electron transfer efficiency from the endogenous.
[0023] In long-term all-electric testing, carbon quantum dot small molecules can overcome the problem of the concentration of the cathode material gradually decreasing as bacteria are passaged, by adding nutrients.
[0024] The carbon quantum dot-infiltrated E. coli electrocatalyst provided by this invention not only exhibits excellent electrocatalytic ORR activity in half-cells, but also demonstrates good bio-power generation capability when assembled into a full cell as a catalytic material for the air cathode of an MFC. Attached Figure Description
[0025] Figure 1 The image shows a TEM image of the catalyst prepared in Example 1.
[0026] Figure 2 The images are laser confocal images, showing wild-type Escherichia coli without the electrocatalyst prepared in Example 1 (a) and laser confocal images prepared in Example 2 (b).
[0027] Figure 3 The CV (a) and LSV (b) plots of the ORR of the catalyst obtained in Example 2 are shown.
[0028] Figure 4 The diagrams shown are power density (a) and stability diagrams obtained in Example 2. Detailed Implementation
[0029] The following specific embodiments of the present invention will provide a detailed and comprehensive description of the technical solutions of the present invention. It should be noted that the provided embodiments represent only a part of the present invention, and not all of it. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.
[0030] Unless otherwise specified, the experimental methods used in the embodiments of this invention are all conventional methods; unless otherwise specified, the materials and reagents used are commercially available reagents and materials, and the commercially available raw materials are used to remove insoluble matter and other impurities by general filtration methods.
[0031] The preparation of carbon quantum dots (carbon dots) is as follows: 250 mg of riboflavin is dissolved in 100 ml of deionized water, and then the freshly prepared solution is placed in a polytetrafluoroethylene reactor. The temperature is set at 160-180℃ and the time is 24 h to carry out a hydrothermal reaction to obtain an aqueous solution containing carbon quantum dots.
[0032] Example 1: Preparation and characterization of carbon dot-infiltrated E. coli electrocatalyst
[0033] Step S1: Centrifuge 100 mL of biosafe E. coli culture medium to obtain bacterial precipitate, wash twice with PBS buffer by centrifugation, then suspend the final bacterial precipitate in PBS solution and vortex for 1 min to obtain bacterial solution;
[0034] Step S2: Add 10-100 μL of carbon spot solution (2.5 g / L) to the above bacterial solution, vortex for 1 min, and then co-culture in a shaker for 2 h; then centrifuge again, discard the supernatant, and use 50 ml of LB liquid medium (10 g / L). -1 Tryptone, 5g / L -1 Yeast extract and 5g L -1 Sodium chloride), thus obtaining the carbon dot infiltration E. coli electrocatalyst.
[0035] Figure 1 Images taken by transmission electron microscopy of carbon dots infiltrating the electrocatalyst of E. coli clearly show that the carbon dots are not only present on the outside of the bacterial membrane but have also penetrated into the interior of E. coli. This indicates that the carbon dots not only affect the conductivity of the electrocatalyst of E. coli as external electronic conductors but also enhance the performance of the electrocatalyst inside the bacteria.
[0036] Figure 2 Laser confocal microscopy (LFM) images of carbon dot-infused E. coli electrocatalysts (b) and wild-type E. coli without carbon dot infusion (a) clearly show that the addition of carbon dot not only did not affect the bioactivity of E. coli, but also increased its biomass. This demonstrates the superior performance of the carbon dot-infused E. coli scheme.
[0037] Example 2
[0038] Application of carbon dot-infiltrated E. coli electrocatalyst in the preparation of biomaterials for air cathodes of microbial fuel cells: The carbon dot-infiltrated E. coli electrocatalyst obtained in Example 1 was added to a 2cm×2cm carbon cloth electrode and placed in a culture medium and co-cultured in a constant temperature shaker for 24h to obtain a biofilm carbon cloth electrode formed by the carbon dot-infiltrated E. coli electrocatalyst and carbon cloth.
[0039] Half-cell electrochemical performance testing: ORR performance testing was conducted on a CHI760E electrochemical workstation (Shanghai Chenhua, China) using a typical three-electrode setup. The carbon cloth electrode (1cm × 1cm) prepared above was used as the working electrode, and a platinum sheet and a saturated silver / silver chloride electrode were used as the counter and reference electrodes, respectively. Electrochemical measurements were performed in an 80mL buffer solution (pH=7) consisting of 22mM KH2PO4, 42mM Na2HPO4, 85.5mM NaCl, 1.0mM MgSO4, and 0.1mM CaCl2. After O2 saturation, the readings were taken at 50mV / s. -1 Cyclic voltammetry (CV) measurements were performed at a scan rate of 5 mV / s. -1 Linear scan voltammetry (LSV) curves were tested at the scanning speed.
[0040] MFC full cell testing: A classic H-type dual-chamber MFC with an internal working volume of 50 mL was used, separated by a proton exchange membrane (DuPont Nafion 211). Carbon cloth (2 cm × 2 cm) served as the base electrode for both the cathode and anode. The electrolyte in the cathode chamber was a 20 mM glucose solution, purged with oxygen for 30 min to remove dissolved nitrogen. The anolyte was a 1 M glucose solution. The carbon cloth electrode prepared above was used as the biocathode, and a commercially available Pt / C-coated carbon cloth electrode was used as the anode. The anode catalyst was 40 wt% Pt / C with a loading of 2 mg / cm³. -2 The voltage of the assembled MFC was evaluated using a CHI760E electrochemical workstation (Shanghai Chenhua, China). Once the MFC voltage reached a steady state, polarization and power density curves were obtained by varying the external resistance (10 ~ 300,000 Ω). The long-term output performance of the MFC was tested using a Keithley 2700 data acquisition system with an external resistance of 1000 Ω. The MFC was operated at 37 °C, and the operation was repeated three times.
[0041] Figure 3 Figure (a) shows the ORR performance of the carbon dot-infiltrated E. coli electrocatalyst prepared in Example 2. As can be seen from Figure (a) CV, this catalyst exhibits excellent catalytic performance, with a maximum current density of 0.31 mA cm⁻¹. -2The starting point is 0.65 V. This is in contrast to the maximum current density of 0.19 mA cm⁻¹ in wild-type fungi. -2 There is a significant improvement. Figure (b) shows that the maximum current density of E. coli infiltrated by carbon dots in the LSV reached 1.16 mA cm⁻¹. -2 Compared to the wild type's 0.80 mA cm⁻¹ -2 There has also been a significant improvement.
[0042] Figure 4 The full-cell performance test of the electrocatalyst prepared in Example 2 was conducted in an H-type two-chamber electrolyzer. Figure (a) shows that the maximum power density of the final MFC of the prepared electrocatalyst is 504.1 μW cm⁻¹. -2 Figure (b) shows that the full cell composed of this catalyst exhibits a stable trend in long-term stability tests.
[0043] Obviously, the above embodiments of the present invention are merely examples to clearly illustrate the technical solution of the present invention, and are not intended to limit the specific implementation of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the claims of the present invention should be included within the protection scope of the claims of the present invention.
Claims
1. A method for preparing an electrocatalyst in which carbon quantum dots are infiltrated into Escherichia coli, characterized by, The method comprises culturing biosafety E. coli, obtaining a culture solution after the culturing, and centrifuging to obtain a bacterial precipitate; then adding an aqueous solution of carbon quantum dots into a buffer solution of the bacterial precipitate for co-culturing to obtain the carbon quantum dots.
2. The method for preparing the carbon quantum dot-infiltrated Escherichia coli electrocatalyst according to claim 1, characterized in that, The carbon quantum dots are obtained by dissolving 100 mg-500 mg of riboflavin in 50-100 ml of water, and then performing hydrothermal reaction at a temperature of 160-180 ℃ for 18-30 h.
3. The method for preparing the electrocatalyst of carbon quantum dots infiltrated into Escherichia coli according to claim 1, characterized in that, After the bacteria are co-cultured with the carbon quantum dots, centrifugal separation is performed to pour supernatant; PBS solution is added into the bacterial solution again, centrifugal separation is performed again, and supernatant is poured to obtain an electrocatalyst of carbon quantum dots infiltrated into E. coli; the co-culturing time is 2-3 h.
4. The method for preparing the electrocatalyst of carbon quantum dots infiltrated into Escherichia coli according to claim 1, characterized in that, The mass concentration of the aqueous solution of the carbon quantum dots is 2-5 g / L; the volume of the buffer solution of the bacterial precipitate is 20-30 ml, and the added amount of the aqueous solution of the carbon quantum dots is 10-100 μL.
5. The electrocatalyst obtained by the preparation method in any one of claims 1 to 4.
6. Application of the electrocatalyst in claim 5 in preparation of a cathode of a microbial fuel cell.
7. Use according to claim 6, characterized in that, The electrocatalyst is suspended in LB liquid medium, and a carbon cloth electrode is placed in the liquid medium to be co-incubated with the bacteria, so that a carbon cloth electrode with an electrocatalyst of carbon quantum dots infiltrated into E. coli biofilm is finally obtained, namely a cathode.
8. Use according to claim 7, characterized in that, The co-incubation was performed using LB liquid medium having a composition of 10 g L -1 Tryptone, 5 g L -1 Yeast extract and 5 g L -1 Sodium chloride; and the co-incubation time was 24 ~ 48 h.
9. A microbial fuel cell, characterized by, The microbial fuel cell cathode is prepared by the electrocatalyst in claim 5.
10. The microbial fuel cell of claim 9, wherein, The cathode liquid is a 20 mM glucose solution, a carbon cloth electrode coated with commercial Pt / C is used as an anode, the anode liquid is a 1 M glucose solution, a proton exchange membrane is used to separate the two chambers, the microbial fuel cell is placed in a 30-37 ℃ incubator, an external resistance is connected, oxygen is introduced into the cathode liquid, and nitrogen is introduced into the anode liquid.