CN109904468B

CN109904468B - Preparation method of bacteria modified carbon electrode

Info

Publication number: CN109904468B
Application number: CN201910119044.9A
Authority: CN
Inventors: 田云; 邓奇; 卢向阳
Original assignee: Hunan Agricultural University
Current assignee: Hunan Agricultural University
Priority date: 2019-02-18
Filing date: 2019-02-18
Publication date: 2022-03-29
Anticipated expiration: 2039-02-18
Also published as: CN109904468A

Abstract

The invention provides a preparation method of a bacteria modified carbon electrode. The method for modifying the carbon electrode by using bacteria greatly reduces the overpotential of the electrode and improves the energy efficiency of the electrode. The abundant heterocarbon elements such as phosphorus, oxygen, nitrogen, sulfur and the like provide reaction sites for reaction species. The structure of the carbon material on the surface of the electrode of the bacteria provides a large amount of effective reaction area for reaction species, greatly improves the reaction activity of the electrode, and shows excellent voltage efficiency and energy efficiency.

Description

Preparation method of bacteria modified carbon electrode

Technical Field

The invention relates to a preparation method of a bacteria modified carbon electrode.

Background

The fossil energy consumption is huge and the environmental pollution problem caused by the fossil energy consumption is increasingly serious, so that renewable clean energy is urgently needed. Wind power and solar power are considered promising as new energy sources in the future. However, solar energy and wind energy are affected by geographical locations, climate changes, and the like, and their development is limited. Therefore, a large-scale energy storage technology is needed to solve the problems of intermittency, discontinuity and the like and provide safe, reliable, continuous and stable electric energy output. The vanadium redox flow battery is a large-scale energy storage technology with application prospect because the vanadium redox flow battery is flexible in design, large in storage capacity and the same element vanadium is used for positive and negative electrolytes, and cross contamination of the positive and negative electrolytes is avoided. The positive and negative electrolytes of the all-vanadium redox flow battery are respectively stored in an external storage tank of the galvanic pile, are conveyed to the surface of the electrode through the action of a pump to generate an oxidation-reduction reaction, and the diaphragm prevents vanadium ions from passing between the positive and negative electrodes and allows protons to pass through to complete the loop of the whole circuit. Through the design, the vanadium redox battery has the characteristics of long cycle life and stability, high energy efficiency, environmental friendliness and the like, and the capacity of the vanadium redox battery can be recovered by simply mixing the positive electrolyte and the negative electrolyte.

The electrode of the flow battery does not participate in chemical reaction, but provides a reaction site for an electrochemical active substance, so that the electrochemical activity of the electrode determines the overall efficiency of the battery, and the electrode is an important component of the flow battery. At present, electrodes of flow batteries mainly comprise carbon materials, in particular graphite felt, carbon paper, carbon cloth and the like. The graphite felt has the advantages of three-dimensional porous structure, good electrochemical stability, high conductivity, good mechanical strength and the like, and is considered to be an electrode material for the flow battery with application prospect. However, the graphite felt is poor in hydrophilicity and low in electrochemical catalytic activity, and further application of the graphite felt in the field of flow batteries is inhibited. In order to improve the overall battery performance of the all-vanadium redox flow battery, the current effective method for modifying the electrode mainly comprises the following steps: (1) noble metals or common metals and metal oxides thereof are used, so that the electrochemical catalytic activity of the electrode is effectively improved, but the cost is too high, and the stability is poor; (2) the graphite felt is treated by using methods such as acid treatment, heat treatment, electrochemical oxidation and the like, so that effective reaction active sites on the surface of the graphite felt are effectively increased, the reversibility of vanadium ions on the surface of an electrode is improved, however, in a liquid flow environment of a battery, oxygen functional groups on the graphite felt are easy to fall off and are unstable in the long-cycle operation process of the battery.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a preparation method of a bacteria modified carbon electrode.

In order to achieve the purpose, the technical scheme provided by the invention is as follows:

the preparation method of the bacteria modified carbon electrode comprises the steps of inoculating bacteria to the inner surface and the outer surface of the electrode, and carbonizing at high temperature to obtain the electrode with a thallus shape.

Preferably, the bacteria are single bacteria or complex bacteria.

More preferably, the bacteria is at least one of cyanobacteria, coccoid bacteria, bacilli, spirochetes, and the like.

Preferably, the carbon electrode is a carbon electrode of an all-vanadium flow battery.

Preferably, the carbon electrode comprises carbon felt, graphite felt, carbon cloth, carbon paper or the like.

Preferably, the method specifically comprises the following steps:

(1) inoculating bacteria to the inner surface and the outer surface of the graphite felt, and culturing at 30-40 deg.C for 12-240 hr to obtain graphite felt electrode with bacteria.

(2) Drying the carbon electrode with bacteria at 40-150 ℃ to constant weight, then placing the carbon electrode in a quartz tube with argon atmosphere, keeping the temperature at 600-1000 ℃ for 0.5-3h, cooling to 15-30 ℃, and then washing and drying to obtain the target electrode.

The electrodes are assembled into an all-vanadium flow battery, and the current density of the battery is measured to be 50-300mA/cm²The current efficiency is 94-98.5%, the voltage efficiency is 95.2-61%, and the energy efficiency is 89.5-60%.

The invention is further illustrated below

The technical route of the invention is as follows: the method comprises the steps of dipping culture media with different concentrations on the inner surface and the outer surface of a carbon electrode, respectively inoculating strains on the inner surface and the outer surface of the electrode, placing the electrode in an incubator for a period of time, drying a sample to constant weight, placing the obtained electrode in a quartz tube in an argon or nitrogen atmosphere, carbonizing the electrode for a plurality of hours at high temperature, cooling the electrode to room temperature, taking out deionized water, washing the electrode, and drying the electrode to constant weight to obtain the target electrode.

By adjusting the conditions of the loading capacity, the culture time, the carbonization temperature and the like of the culture medium in the carbon electrode, the carbon material rich in oxygen, phosphorus, sulfur and other carbon elements is loaded on the surface of the carbon electrode. The composite electrode shows high catalytic activity, high energy efficiency and long cycle stability in the charge and discharge processes of the all-vanadium redox flow battery. The material source is wide, the preparation process is simple, the environment is friendly, the performance is outstanding, and the material is expected to be applied to the all-vanadium redox flow battery in a large scale.

Drawings

FIG. 1 is a comparison graph of cyclic voltammetry between an experimental group and a blank group in example 1 of the present invention;

FIG. 2 shows the current density of 200mA/cm between the modified graphite felt and the blank electrode in example 1 of the present invention²A plot of voltage versus time under conditions;

FIG. 3 is a scanning electron micrograph of the carbon electrode modified with bacteria in example 1 of the present invention.

Detailed Description

The invention is further illustrated by the following examples. The raw materials used in the invention are all conventional reagents which are easy to purchase, and the adopted test methods are all conventional in the field.

Example 1

Drying the dipping culture medium, then carrying out liquid spraying on a graphite felt with the spraying inoculation amount of 5% of bacillus mycoides in a 3 x 4cm manner, culturing for 12h in an incubator, taking out and drying to constant weight, carbonizing for 1h at 700 ℃ in a quartz tube under the argon protection atmosphere, taking out and washing the sample when the furnace temperature is reduced to room temperature, and drying to constant weight to obtain the target electrode. The electrode was assembled into a battery at a current density of 50mA/cm²In the case of the charge and discharge test, the energy efficiency was 89.5% and the current efficiency was 94%. The results are shown in FIGS. 1 to 3.

Example 2

Drying the dipping culture medium, then carrying out liquid spraying on a graphite felt with the spraying inoculation amount of 10% of bacillus mycoides in a 3 x 4cm manner, culturing for 24h in an incubator, taking out and drying to constant weight, carbonizing for 2h at 800 ℃ in a quartz tube under the argon protection atmosphere, taking out and washing the sample when the furnace temperature is up to room temperature, and drying to constant weight to obtain the target electrode. The electrode was assembled into a battery at a current density of 100mA/cm²In the case of the charge and discharge test, the energy efficiency was 84% and the current efficiency was 97%.

Example 3

Drying the dipping culture medium, then carrying out liquid spraying on a 3 x 4cm graphite felt with the inoculation amount of 15% blue algae, culturing in an incubator for 36h, taking out and drying to constant weight, carbonizing at 900 ℃ in a quartz tube under the protection of argon for 3h, taking out and washing the sample when the furnace temperature is up to room temperature, and drying to constant weight to obtain the target electrode. The electrode was assembled into a battery at a current density of 150mA/cm²In the case of the charge and discharge test, the energy efficiency was 81%, and the current efficiency was 98%.

Example 4

Drying the immersion culture medium, inoculating blue algae with 3 × 4cm of graphite felt liquid with the inoculation amount of 20%, culturing in an incubator for 72h, taking out, drying to constant weight, carbonizing at 900 deg.C under argon protection in a quartz tube for 2h, and heating to room temperatureAnd taking out the sample at a certain temperature, washing, and drying to constant weight to obtain the target electrode. The electrode was assembled into a battery at a current density of 200mA/cm²In the case of the charge and discharge test, the energy efficiency was 75%, and the current efficiency was 98.5%.

Claims

1. A preparation method of a bacteria modified carbon electrode is characterized in that bacteria are inoculated on the inner surface and the outer surface of the carbon electrode, and then the electrode with a thallus shape is obtained by high-temperature carbonization; the carbon electrode is a carbon electrode of the all-vanadium redox flow battery; the bacteria is at least one of blue algae, coccoid bacteria, bacillus and spirochete bacteria; the method specifically comprises the following steps: (1) inoculating bacteria to the inner surface and the outer surface of the carbon electrode, and culturing at 30-40 deg.C for 12-240 hr to obtain carbon electrode with bacteria; (2) drying the carbon electrode with bacteria at 40-150 ℃ to constant weight, then placing the carbon electrode in a quartz tube in argon atmosphere, keeping the temperature at 600-1000 ℃ for 0.5-3h, cooling to 15-30 ℃, and then washing and drying to obtain the target electrode.

2. The method of claim 1, wherein the carbon electrode comprises a carbon felt, a graphite felt, a carbon cloth, or a carbon paper.