KR102470623B1 - Method for preparing nanocellulose electrode and Electrode prepared thereby - Google Patents

Abstract

The present invention relates to a method for manufacturing a nanocellulose electrode and a nanocellulose electrode manufactured thereby. Specifically, according to the production method of the present invention, nanocellulose obtained by culturing bacteria can be electroless and electroplated to produce an electrode. Since the method of the present invention uses bacterial nanocellulose, it is not only eco-friendly and inexpensive, but also can easily form a metal layer by using a small amount of low-cost metal instead of expensive metal such as platinum, so the manufacturing cost is reduced and economical compared to the prior art. to be. In addition, the electrode prepared by this method has excellent conductivity, a wide surface area, and excellent catalytic properties, so when used as a hydrogen generating electrode, the hydrogen generating efficiency and hydrogen production ability are excellent. Moreover, since the electrode has flexibility according to the use of nanocellulose, it can be folded or rolled, so it can be implemented in various types of products without space limitations.

Description

Method for preparing nanocellulose electrode and electrode prepared thereby {Method for preparing nanocellulose electrode and Electrode prepared thereby}

The present invention relates to a method for manufacturing a nanocellulose electrode and an electrode manufactured thereby, and more particularly, to a method for manufacturing a nanocellulose electrode in which nanocellulose obtained by culturing bacteria is coated with a metal, and an electrode manufactured thereby. .

The electrochemical hydrogen generation reaction by electrolysis of water is more environmentally friendly because it can easily produce hydrogen and uses renewable energy.

Conventionally, it has been known that electrolysis using a platinum electrode can produce hydrogen most efficiently. However, the use of such a platinum electrode has a disadvantage in terms of economy due to the high price of platinum although the hydrogen production efficiency is high. In particular, it was economically difficult to use expensive platinum electrodes in conducting large-scale reactions. In addition, since the flexibility of the metal electrode is low, it is difficult to manufacture various types of products.

On the other hand, as products diversify due to the rapid growth of the high-tech convergence industry, research on new high value-added materials is being actively conducted. Among them, biomass-based nanocellulose can be approached in various ways from a physical, chemical, and biological point of view. Nanocellulose obtained by culturing bacteria is flexible and has excellent mechanical properties such as strength, so it is being studied for use as electrical and electronic materials such as substrates as well as medical and cosmetic materials.

An object of the present invention is to provide a method for manufacturing an electrode inexpensively and easily while having excellent performance as an electrode.

The above object of the present invention could be achieved by using nanocellulose obtained by culturing bacteria and coating it with a metal layer to use it as an electrode.

Accordingly, according to one aspect of the present invention, (a) electrolessly plating nanocellulose obtained by culturing bacteria and (b) electroplating a metal on the electroless plated nanocellulose, A method for manufacturing a nanocellulose electrode is provided.

According to one embodiment of the present invention, the (a) electroless plating step includes (a-1) treating the nanocellulose with a first catalyst, (a-2) treating the nanocellulose with the first catalyst activating by treatment with a second catalyst; and (a-3) electroless plating the nanocellulose activated with the second catalyst.

According to another embodiment of the present invention, the bacteria are Acetobacter genus, Pseudomonas genus, Rhizobium genus, Agrobacteria genus, Saracina genus, Azoto It may be at least one selected from the genus Azotobacter and the genus Komagataeibacter .

According to another embodiment of the present invention, the first catalyst may be a tin compound.

According to another embodiment of the present invention, the tin compound may be at least one selected from the group consisting of tin chloride, tin sulfate, tin sulfamate, tin methanesulfonate, and tin pyrophosphate.

According to another embodiment of the present invention, the second catalyst may be a palladium compound.

According to another embodiment of the present invention, the palladium compound may be at least one selected from the group consisting of palladium chloride, palladium sulfate, palladium acetate, tetraamine palladium chloride, dinitrodiamine palladium, and dichlorodiethyleneamine palladium. .

According to another embodiment of the present invention, the electroless plating in step (a-3) may be performed by contacting the nanocellulose with an electroless plating composition containing a nickel compound.

According to another embodiment of the present invention, the nickel compound may be at least one selected from the group consisting of nickel sulfate, nickel chloride, nickel nitrate, and nickel acetate.

According to another embodiment of the present invention, the (b) electroplating step may be performed by contacting the nanocellulose with an electroplating composition containing a nickel ion source and a molybdenum ion source.

According to another embodiment of the present invention, the nickel ion source may be at least one selected from the group consisting of nickel sulfate, nickel sulfamate, nickel chloride, nickel acetate, and hydrates thereof.

According to another embodiment of the present invention, the molybdenum ion source may be at least one selected from the group consisting of molybdic acid, sodium molybdate, potassium molybdate, ammonium molybdate, and hydrates thereof.

According to another aspect of the present invention, a nanocellulose electrode prepared by the above method may be provided.

According to one embodiment of the present invention, the nanocellulose electrode can be used as a hydrogen generating electrode.

Since the method of the present invention uses bacterial nanocellulose, it is not only eco-friendly and inexpensive, but also can easily form a metal layer by using a small amount of low-cost metal instead of expensive metal such as platinum, so the manufacturing cost is reduced and economical compared to the prior art. to be. In addition, the electrode prepared by this method has excellent conductivity, a wide surface area, and excellent catalytic properties, so when used as a hydrogen generating electrode, the hydrogen generating efficiency and hydrogen production ability are excellent. Moreover, since the electrode has flexibility according to the use of nanocellulose, it can be folded or rolled, so it can be implemented in various types of products without space limitations.

The electrode according to the present invention generates hydrogen by electrolysis using renewable energy and uses the generated hydrogen to produce methane in the Power to Gas (P2G) field, generates hydrogen by electrolysis, or electrochemically oxidizes and reduces It can be applied to the electrochemical field that requires a reaction, the fuel cell and hydrogen vehicle field that uses hydrogen directly as fuel, and the existing petrochemical process field that requires hydrogen.

1 shows a method for preparing bacterial nanocellulose according to an embodiment of the present invention.
2 shows a method of manufacturing an electrode according to an embodiment of the present invention.
Figure 3 shows the results of confirming the characteristics of the electrode according to an embodiment of the present invention through (a) XRD and XPS (b)-(e) analysis.
Figure 4 shows the results of confirming the characteristics of the electrode according to an embodiment of the present invention through TEM and EDS analysis.
5 shows the results of comparing and conducting a hydrogen production reaction using a NiMoO ₄ /BNC electrode, a platinum electrode, and a NiOx-BNC electrode according to an embodiment of the present invention.
Figure 6 shows the NiMoO ₄ /BNC electrode according to an embodiment of the present invention and the current density according to the potential of the hydrogen generation reaction using the same.

Hereinafter, the present invention will be described in detail.

The terms used in this application are only used to describe specific embodiments and are not intended to limit the present invention. Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

Throughout the specification, when a part “includes,” “includes,” or “has” a certain component, it means that it may further include other components unless otherwise specifically defined.

Terms such as first, second, A, B, etc. may be used to describe various elements, but the elements are not limited by the above terms, and are merely used to distinguish one element from another. used only as

1. Manufacturing method of nanocellulose electrode

According to one aspect of the present invention, nanocellulose comprising the steps of (a) electroless plating nanocellulose obtained by culturing bacteria and (b) electroplating a metal on the electroless plated nanocellulose A method of manufacturing an electrode is provided.

According to one embodiment of the present invention, the manufacturing method of the present invention may further include culturing bacteria and recovering the cultured nanocellulose before performing step (a).

Here, the bacterium is not particularly limited as long as it is a bacterium capable of producing nanocellulose, but specifically, for example, Acetobacter genus, Pseudomonas genus, Rhizobium genus, Agrobacteria At least one member selected from the genus, Saracina genus, Azotobacter genus, and Komagataeibacter genus, more specifically, Acetobacter genus or Komagataeibacter ) can be fooled. More specific examples of the bacteria include Acetobacter pasteurianus, Acetobacter aceti, Acetobacter xylinum, Acetobacter ransens , Komagataeibacter sucrofermentans , and the like.

The culturing may be performed in a medium containing a carbon source, for example, glucose. The medium used for culturing microorganisms may be any conventional medium suitable for the growth of host cells, such as minimal or complex medium containing appropriate supplements.

Conditions of the culture may be appropriately adjusted to suit the production of a selected product, for example, cellulose. The culture may be performed under aerobic conditions for cell proliferation. The culture may be a spinner culture or a static culture without agitation. The concentration of the microorganisms may be such that an interval is provided that does not interfere with the production of cellulose.

According to the culture, the nanocellulose formed on the upper layer of the culture medium can be formed in the form of a thin film. The nanocellulose thin film formed on the top of the culture medium can be physically removed or recovered by removing the medium.

The step (a) is a step of electroless plating the nanocellulose obtained by culturing bacteria, which includes (a-1) treating the nanocellulose with a first catalyst, (a-2) using the first catalyst activating the treated nanocellulose by treating it with a second catalyst; and (a-3) electroless plating the nanocellulose activated with the second catalyst.

The step (a-1) may be performed by contacting a solution containing the first catalyst with the nanocellulose, specifically by supporting the nanocellulose in the solution. Here, the first catalyst may be a tin compound, and the tin compound may be, for example, at least one selected from the group consisting of tin chloride, tin sulfate, tin sulfamate, tin methanesulfonate, and tin pyrophosphate. . The solution containing the first catalyst may further contain an additional additive such as a pH adjuster in addition to the first catalyst. The pH adjusting agent may be selected from the group consisting of inorganic acids, for example, hydrochloric acid, sulfuric acid, and nitric acid. Treatment conditions with the first catalyst can be appropriately selected by a person skilled in the art, and is usually carried out at room temperature without stirring, which is to sensitize the surface of nanocellulose. After the sensitization by support in step (a-1), washing and drying the nanocellulose may be further included.

The step (a-2) may be performed by contacting the nanocellulose treated with the first catalyst with a solution containing the second catalyst, specifically by supporting the nanocellulose in the solution. Here, the second catalyst may be a palladium compound, and the palladium compound is, for example, from the group consisting of palladium chloride, palladium sulfate, palladium acetate, tetraamine palladium chloride, dinitrodiamine palladium, and dichlorodiethyleneamine palladium. It may be at least one kind selected. The solution containing the second catalyst may further contain an additional additive such as a pH adjuster in addition to the second catalyst. The pH adjusting agent may be an inorganic acid as described in step (a-1) above, and is usually carried out at room temperature without stirring. Step (a-2) is performed to activate the surface of the nanocellulose, and as a result, a first catalyst seed and a second catalyst seed may be formed on the surface of the nanocellulose. A step of washing the nanocellulose after the activation may be further included, and decomposition due to contamination may be prevented in a later electroless plating step through the washing.

The step (a-3) is a step of electroless plating the nanocellulose, which is carried out by contacting the nanocellulose activated through the step (a-2) with an electroless plating composition, specifically, the electroless plating composition. It can be done by doing Here, the electroless plating composition may contain a nickel compound, and the nickel compound may be, for example, at least one selected from the group consisting of nickel sulfate, nickel chloride, nickel nitrate, and nickel acetate. The electroless plating composition may further contain one or more additional additives such as a complexing agent, a reducing agent, and a stabilizer in addition to the nickel compound. Examples of the complexing agent include thiourea, glycolic acid, lactic acid, tartric acid, malic acid, aminosuccinic acid, citric acid, gluconic acid, and the like. Examples of the reducing agent include hypophosphorous acid, sodium hypophosphite, potassium hypophosphite, and ammonium hypophosphite. In addition, examples of the stabilizer include citric acid, citric acid hydrate, thiosulfate, sulfite, thioglycolic acid, thioglycol polyethoxylate, potassium cyanide, and the like.

Reaction conditions for electroless plating can be appropriately selected by a person skilled in the art. For example, nanocellulose is supported in the electroless plating composition, supported at 20 to 150 ° C. for 10 seconds to 30 minutes, and then washed 0 to 4 times. can be carried out. Through the electroless plating, a metal catalyst in the plating composition, for example, nickel of a nickel compound, can form a layer on the nanocellulose, so that the nanocellulose can have appropriate conductivity to perform the electroplating described later. .

Step (b) is a step of electroplating a metal on the electroless plated nanocellulose. The electroplating may be performed by contacting the nanocellulose with an electroplating composition, specifically, by supporting it in the electroplating composition. Here, the electroplating composition may contain a nickel ion source and a molybdenum ion source. The nickel ion source may be, for example, at least one selected from the group consisting of nickel sulfate, nickel sulfamate, nickel chloride, nickel acetate, and hydrates thereof, and the molybdenum ion source may be, for example, molybdic acid, It may be at least one selected from the group consisting of sodium molybdate, potassium molybdate, ammonium molybdate, and hydrates thereof. In addition to the nickel ion source and the molybdenum ion source, the electroplating composition may further contain one or more additional additives such as a buffer, a reducing agent, a complexing agent, and a surfactant. Examples of the buffering agent include acetic acid, aminoacetic acid, boric acid, and the like, and examples of the reducing agent include hypophosphorous acid, sodium hypophosphite, potassium hypophosphite, and ammonium hypophosphite. In addition, examples of the complexing agent include potassium sodium L-tartrate tetrahydrate (C ₄ H ₄ KNaO ₆ 4H ₂ O), trisodium citrate dihydrate (C ₆ H ₅ Na ₃ O ₇ 2H ₂ O), and the like. can be heard Further, examples of the surfactant include anionic surfactants such as sodium di(1,3-dimethylbutyl) sulfosuccinate, sodium-2-ethylhexyl sulfate, sodium diamyl sulfosuccinate, sodium lauryl sulfate, sodium lauryl ether-sulfate, sodium di-alkylsulfosuccinate and sodium dodecylbenzene sulfonate, and cationic surfactants such as quaternary ammonium salts such as perfluorinated quaternary amines.

The electroplating may be performed using nanocellulose having conductivity as a cathode, and in this case, an anode for electroplating such as nickel foam may be used. Specific reaction conditions for electroplating can be appropriately selected by a person skilled in the art. For example, the electroplating composition may be acidic, specifically in the range of pH 2 to 6, more specifically pH 3 to 5.5, for which a pH adjusting agent such as hydrochloric acid may be added. During plating, the composition temperature may range from room temperature to 70 °C, specifically from 30 to 60 °C, more specifically from 40 to 60 °C, and the current density is 0.1 A/cm ² or more, specifically from 0.1 to 30 A /cm ² range. A metal, specifically, a nickel molybdenum alloy catalyst layer may be formed on the nanocellulose by the electroplating, and at this time, the thickness of the metal catalyst layer may be in the range of 1 μm or more, more specifically, 1 to 100 μm. have. After the electroplating is finished, a step of washing the nanocellulose electrode may be further included.

2. Nanocellulose electrode

According to another aspect of the present invention, the present invention provides a nanocellulose electrode prepared by the above-described manufacturing method.

The nanocellulose electrode may be specifically used as a hydrogen generating electrode, more specifically, as a hydrogen generating electrode of a fuel cell. Since the electrode of the present invention is formed by electroplating metal on nanocellulose, it is flexible and can be applied in various forms such as folding or rolling to various products such as fuel cells in which hydrogen generating electrodes are used.

Hereinafter, a preferred embodiment is presented to aid understanding of the present invention. However, the following examples are provided to more easily understand the present invention, and the content of the present invention is not limited by the following examples.

[Example]

Example 1: Bacterial nanocellulose production

As shown in FIG. 1, bacterial nanocellulose was produced using Komagataeibacter sucrofermentans DSM 15973 strain. After culturing the strain in Hestrin-Schramm (HS) medium for 10 days, the bacterial nanocellulose generated on the upper layer of the culture medium was treated with 0.1M NaOH and 80 ° C for 2 hours, and then washed with deionized water. The thickness of bacterial cellulose before drying was measured to be about 150 μm, and the thickness after drying was about 20 μm.

Example 2: Bacterial nanocellulose electrode and NiMoO ₄ /Manufacture of BNC electrode

As shown in FIG. 2, an electrode was prepared by coating bacterial nanocellulose with a metal.

First, the bacterial nanocellulose was made conductive through the following electroless plating method. Bacterial nanocellulose pieces were put in 0.05M SnCl ₂ and 12M HCl solution, reacted for 10 minutes at room temperature, washed and dried, put in 0.03M HCl and 100μg/ml PdCl ₂ solution, reacted and washed for 15 minutes at 30 °C, and finally 0.05M Put NiSO ₄ 6H ₂ O, 0.10MC ₆ H ₈ O ₇ H ₂ O into the solution, inject NaH ₂ PO ₂ H ₂ O as a reducing agent at 70℃ and pH 10, react for 25-30 minutes, and then react with ethanol. washed with water

Bacterial nanocellulose, which became conductive through the electroless plating method, was coated with a nickel molybdenum alloy catalyst by the electroplating method. After connecting bacterial nanocellulose as cathode and nickel foam as anode to the power supply, 40 ml electrolyte solution (3.16g NiSO ₄ 6H ₂ O, 1.92g Na ₂ MoO ₄ 2H ₂ O, 3.52 g g Na ₃ C ₆ H ₅ O ₇ 2H ₂ O), and coating was performed at a current density of 0.16 A/cm ² for 20 minutes. The coated electrode was washed with water and ethanol and dried before use.

Example 3: Bacterial nanocellulose characterization

In order to confirm the characteristics of the electrode prepared according to the present invention, XRD, XPS, SEM, and TEM analyzes were performed. The results are shown in Figure 3.

As shown in (a) of FIG. 3, through XRD analysis, bacterial nanocellulose (BNC) without any treatment, bacterial nanocellulose (NiOx / BNC) after electroless plating treatment, nickel molybdenum catalyst coating by electroplating method It is possible to confirm the pattern difference between the three materials of bacterial nanocellulose (NiMoO ₄ /BNC).

The surface atomic composition state of NiMoO ₄ /BNC was confirmed through XPS analysis, as shown in (b)-(e) of FIG. 3 . Through this, various electronic positions of Ni 2p _1/2 , Ni 2p _3/2 , Mo 3d _3/2 , and Mo 3d _5/2 were confirmed, and the surface composition of NiMo@C and NiMoO ₄ @C types can be predicted. .

As shown in FIG. 4, through the TEM and EDS mapping pictures, it was confirmed that NiMoO ₄ was uniformly present and existed in the form of an alloy through electroplating.

Example 4: Analysis of electrochemical characteristics through hydrogen production reaction

The hydrogen production reaction was conducted and compared using the NiMoO ₄ /BNC electrode, the platinum electrode, and the NiOx-BNC electrode. The results are shown in FIG. 5 .

As shown in (a) of FIG. 5, when comparing the over potential value when reaching 10 mA cm ^-2 for each electrode, the NiMoO ₄ /BNC electrode has a value more than 5 times lower than the NiOx-BNC electrode , and a small difference of about 40 mV was confirmed even when compared to the platinum electrode.

Comparing the ^Tafel slope, which is an important indicator of the hydrogen generation reaction, for the three electrodes, as _shown in (b) of FIG. It was confirmed that it is more suitable for the hydrogen evolution reaction.

As for the stability of the electrochemical catalyst of the NiMoO ₄ /BNC electrode, as shown in (c) of FIG. 5, it was confirmed that the catalytic activity was maintained without a significant decrease in current density even after 24 hours of reaction.

Figure 6 shows the electrode manufactured according to the present invention and the current density according to the potential of the hydrogen generation reaction using the same. As shown in FIG. 6, it can be confirmed that the electrode prepared by coating the bacterial nanocellulose with NiMoO ₄ according to the present invention can have high efficiency in hydrogen generation reaction.

The above description of the present invention is for illustrative purposes, and those skilled in the art can understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, the embodiments described above should be understood as illustrative in all respects and not limiting.

Claims (14)

(a) electroless plating of nanocellulose obtained by culturing bacteria and
(b) electroplating a metal on the electroless plated nanocellulose;
The bacteria are of the genus Komagataeibacter,
The (a) electroless plating step
(a-1) treating the nanocellulose with a first catalyst;
(a-2) activating the nanocellulose treated with the first catalyst by treating it with a second catalyst; and
(a-3) electroless plating the nanocellulose activated with the second catalyst;
The first catalyst is a tin compound,
The second catalyst is characterized in that the palladium compound
Manufacturing method of nanocellulose electrode. delete delete delete The method of claim 1, wherein the tin compound is at least one selected from the group consisting of tin chloride, tin sulfate, tin sulfamate, tin methanesulfonate, and tin pyrophosphate. delete The method according to claim 1, wherein the palladium compound is at least one selected from the group consisting of palladium chloride, palladium sulfate, palladium acetate, tetraamine palladium chloride, dinitrodiamine palladium, and dichlorodiethyleneamine palladium. The method of claim 1, wherein the electroless plating in step (a-3) is performed by contacting the nanocellulose with an electroless plating composition containing a nickel compound. 9. The method of claim 8, wherein the nickel compound is at least one selected from the group consisting of nickel sulfate, nickel chloride, nickel nitrate, and nickel acetate. The method of claim 1, wherein the electroplating step (b) is performed by contacting the nanocellulose with an electroplating composition containing a nickel ion source and a molybdenum ion source. 11. The method of claim 10, wherein the nickel ion source is at least one selected from the group consisting of nickel sulfate, nickel sulfamate, nickel chloride, nickel acetate, and hydrates thereof. 11. The method of claim 10, wherein the molybdenum ion source is at least one selected from the group consisting of molybdic acid, sodium molybdate, potassium molybdate, ammonium molybdate, and hydrates thereof. A nanocellulose electrode prepared by the method according to claim 1. The nanocellulose electrode according to claim 13, characterized in that it is used as a hydrogen generating electrode.

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