Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
  • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
  • G01N27/28—Electrolytic cell components
  • G01N27/30—Electrodes, e.g. test electrodes; Half-cells
  • G01N27/308—Electrodes, e.g. test electrodes; Half-cells at least partially made of carbon

Definitions

• the present invention relates to an electrode material and an energy conversion device using the same, and more particularly to an electrode material made of a carbon composite material and an energy conversion device using the same.
• the present invention has been made in view of the above-described problems of the prior art, and can provide sufficient stability and excellent activity of the support component, and can efficiently achieve the efficiency between the support and the support component. It is an object of the present invention to provide an electrode material capable of efficient electronic conduction and an energy conversion device using the same.
• the electrode material of the present invention comprises a carbon porous body and an oxidoreductase supported on the carbon porous body.
• the carbon porous body that is effective in the present invention has a specific surface area of 100 m 2 Zg or more and a pore diameter distribution region of 2 ⁇ ! Based on the total pore volume in the range of ⁇ lOOnm, the pore volume in the range of ⁇ 25% of the average pore diameter is preferably 60% or more.
• the pore size value at the top of the distribution peak is in the range of 1 nm or more and less than lOnm, the pore size range of d 2 nm with respect to the pore size value (d).
• the pore size value at the top of the distribution peak is in the range of 10 nm or more and 50 ⁇ m or less, (0) with respect to the pore size value (D) 75 XD) to (1.25 XD)
• a carbon gel containing 60% or more of the total pore volume in the pore diameter region is preferable.
• the pore diameter value of the carbon gel force distribution peak top is 1
• the carbon gel force average particle diameter is composed of primary particles having a particle diameter of 2 to 50 nm.
• the acid reductase that is effective in the present invention is preferably at least one enzyme selected from the group powers of laccase and pyrilvin oxidase.
• the electrode material of the present invention further includes an electron transmission material supported on the carbon porous body.
• the carbon porous body has pores, and at least a part of the acid-reductase is supported in the pores. I prefer to be there.
• an energy conversion device of the present invention comprises the electrode material of the present invention.
• an electrode material capable of obtaining sufficient stability and excellent activity of the supported component and capable of efficient electron conduction between the carrier and the supported component and the same are used.
• An energy conversion device can be provided.
• FIG. 1 is a cyclic voltammogram obtained using an electrode whose surface is modified with the electrode material obtained in Example 5.
• FIG. 2 is a cyclic voltammogram obtained using an electrode whose surface is modified with the electrode material obtained in Comparative Example 1.
• Fig. 3 is a cyclic voltammogram obtained by using an electrode obtained by modifying the electrode material obtained in Example 7 and Comparative Example 2 on the surface.
• FIG. 4 is a cyclic voltammogram showing the cyclic voltagram shown in FIG. 3 in an enlarged range of 200 to 100 ⁇ current.
• the electrode material of the present invention includes a carbon porous body and an acid reductase supported on the carbon porous body.
• mesoporous carbon particles or carbon gels which are carbon porous bodies having a specific surface area, pore diameter and pore volume, which can sufficiently improve the stability and activity of the supported component. Is contained, and so-called carbon black is not contained.
• the average pore diameter of such a carbon porous body is preferably 2 to 50 nm, particularly preferably 2 to 20 nm! /. If the average pore diameter of the carbon porous body is less than 2 nm, the pore size tends to be smaller than the size of the supported component, and the adsorptivity tends to decrease. There is a tendency for the specific surface area to decrease and the adsorptivity to decrease. Further, when the average pore diameter of the carbon porous body exceeds 20 nm, there is a tendency that inconvenience is likely to occur when a part of the supporting component is supported.
• the average pore size of the carbon porous body according to the present invention is preferably equal to or larger than the molecular size of the supported component. More preferably, it is about 1 to 1.25 times the diameter.
• the average pore diameter of the carbon porous material that is useful in the present invention is as described above, the supported component is finely matched to the molecular diameter. Because it is fixed in the pores, the outer wall of the pores suppress structural changes that occur when the supported component is deactivated by heat, so that the deactivated supported component can be prevented and the thermal stability is improved. Tend to.
• the pore size distribution region is 2 ⁇ ! Based on the total pore volume in the range of ⁇ lOOnm, those having a pore volume in the range of ⁇ 25% of the average pore diameter of 60% or more are preferable. If the uniformity of the pore size is worse than this, there will be more pore components other than the optimum pore size for supporting the oxidative reduction enzyme and other supporting components, and the stability and activity of the acid reduction enzyme will be sufficiently improved. There is a tendency to ⁇ .
• the specific surface area of the porous carbon material according to the present invention is preferably 100 m 2 / g or more, more preferably 500 to 1000 m 2 Zg.
• the specific surface area force of the carbon porous body is less than Sl00m 2 Zg, the contact area with the supporting component is reduced and the pores taking in the supporting component are reduced, so that the adsorptivity tends to be low.
• the pore volume of the carbon porous body according to the present invention is not particularly limited because it varies depending on the specific surface area and the average pore diameter, but is preferably 0.1 to 50 mlZg, and 0.2. More preferably, it is -2.5 mlZg.
• pores having a pore diameter equal to or larger than the molecular diameter of the oxidoreductase are used.
• the total volume is preferably equal to or greater than the total volume of the supported acid reductase.
• the specific surface area, average pore diameter and pore volume of the carbon porous body according to the present invention can be determined by the methods described below. That is, the carbon porous body is put in a predetermined container, cooled to liquid nitrogen temperature (196 ° C.), nitrogen gas is introduced into the container, and the adsorption amount is obtained by a constant volume method or a gravimetric method. Next, the pressure of the introduced nitrogen gas is gradually increased, and the nitrogen gas adsorption isotherm is obtained by plotting the nitrogen gas adsorption amount with respect to each equilibrium pressure. Using this nitrogen adsorption isotherm, the specific surface area, average pore diameter and pore volume can be calculated by the SPE (Subtracting Pore Effect) method (K.Kaneko, C.Ishii, M.Ruike,
• the calculation is more accurate than the BET method.
• the mesoporous carbon particles are based on the whole pore volume in the pore size distribution of 2 to 100 nm, 2 to: the pore volume in the pore size distribution of LOnm is 80% or more,
• the carbon particles have mesopores. Examples of methods for measuring such pore size distribution include XRD and nitrogen adsorption methods.
• the method for producing such mesoporous carbon particles is not particularly limited, and for example, the following method can be employed. That is, porous particles such as silica and titer are adsorbed and impregnated with organic molecules such as sucrose and furfuryl alcohol, and then carbonized in an inert atmosphere. Thereafter, mesoporous carbon particles having porous particles such as silica in a bowl shape can be produced by dissolving and removing the particles in a bowl shape such as silica with hydrofluoric acid or NaOHZEtOH. For example, silica mesoporous MCM-48 can be used as a porous porous particle.
• the carbon gel satisfies the following conditions (i) to (ii).
• MPC mesoporous carbon
• a carbon gel as a carrier, the reason and the activity are surprisingly improved, although the reason is not clear.
• the carbon gel is an aggregate having the primary particle force, and in the pore size distribution calculated from the adsorption / desorption isotherm, (ii 1) the pore size value of the distribution peak top is not less than lnm and less than lOnm. In the range of the pore diameter value (d), the pore diameter region of d 2 nm contains 60% or more of the total pore volume, and (ii-2) the distribution peak top.
• the pore diameter value of s is in the range of lOnm or more and 50 nm or less, all pores are in the pore diameter region of (0.75 XD) to (1.25 XD) nm with respect to the pore diameter value (D). It contains more than 60% of capacity. If the uniformity of the pore diameter is worse than this, the number of pore components other than the optimum pore diameter for supporting an enzyme or the like increases, and the obtained effect is reduced.
• the pore size value of the distribution peak top of the carbon gel is preferably 1 to 20 nm.
• the pore size value of the carbon gel is less than 1 nm, the pore size is often smaller than the size of the supported component, and the adsorptivity is reduced.
• the specific surface area is reduced. And the adsorptivity decreases.
• the pore diameter value of the carbon gel exceeds 20 nm, there is a tendency that inconvenience is likely to occur when the supporting component is supported.
• the carbon gel is preferably one having an average particle size of primary particle force of 2 to 50 nm, more preferably an average particle size of 20 nm. If the average particle size of the primary particles constituting the carbon gel is less than 2 nm, the size of the pores is often smaller than the size of the supported component, and the adsorptivity is reduced, whereas if the average particle size exceeds 50 nm. The specific surface area is reduced and the adsorptivity is reduced. [0037]
• the method for producing such a carbon gel is not particularly limited, and can be suitably produced by employing a conventionally known method. Examples of a method for producing such a carbon gel include the method described below.
• a suitable enzyme suitable for the present invention is appropriately selected depending on whether the electrode material of the present invention is used as the positive electrode material or the negative electrode material.
• the acid-reducing enzyme according to the present invention is not particularly limited as long as it is an enzyme that can receive electrons by reaction.
• laccase bilirubin oxidase which can catalyze the reaction that produces water using tons and oxygen as substrates.
• the oxidoreductase according to the present invention is not particularly limited as long as it is an enzyme capable of releasing an electron by reaction, and alcohol is converted to acid.
• examples thereof include alcohol dehydrogenase capable of catalyzing a reaction that releases electrons, aldehyde dehydrogenase that oxidizes aldehyde and formic acid, and formate dehydrogenase.
• a corresponding oxidase such as oxidase or dehydrogenase can be used according to the raw material for supplying electrons.
• Alcohol oxidase using alcohol as a raw material organic acid dehydrogenase using organic acid such as formic acid as a raw material, and glucose oxidase such as glucose oxidase and glucose dehydrogenase using saccharide as a raw material are preferable.
• hydrogenase from hydrogen is also preferably used. It can be done.
• the electrode material of the present invention comprises a carbon porous body and an acid reductase supported on the carbon porous body.
• the amount of acid reductase supported on the carbon porous body is not particularly limited as long as the enzyme activity is shown, but the obtained electrode material has sufficient oxidoreductase. From the viewpoint of exhibiting activity, it is preferable that the loading amount of the oxidoreductase is about 0.01 to 80 parts by mass with respect to 100 parts by mass of the carbon porous body.
• the method for obtaining the electrode material of the present invention by supporting an oxidoreductase on a carbon porous body is not particularly limited, and methods such as a sublimation method and an impregnation method can be employed.
• the following impregnation method is more preferred. That is, first, the acid reductase is dissolved in water or a buffer solution so as to have a concentration at which precipitation does not occur (preferably 0.1 mgZml to 1000 mgZml). Then, suspend the porous carbon body at a temperature (preferably 0 ° C to 50 ° C) that does not freeze the solution and does not denature the oxidoreductase, and it is preferable for at least 5 minutes or more. In this case, the acid reductase is immobilized in the pores of the carbon porous body by contacting the acid reductase with the carbon porous body for 30 minutes or more to obtain the electrode material of the present invention.
• the concentration when the carbon porous body is suspended in the above solution is not particularly limited, but is preferably about 0.1 to lOOOOmgZml. Further, after the supporting step, there is a step of further separating the porous carbon composite material from the solution by performing centrifugal separation or the like, and removing the liquid component by performing drying or the like. It is possible to have a step of obtaining the carbon porous composite material in a state of being!
• the electrode material of the present invention preferably further comprises an electron transfer substance supported on the carbon porous body.
• an electron transfer substance By further supporting an electron transfer substance in addition to the acid reductase on the carbon porous body, the electron transfer substance and the oxidoreductase combine to tend to enable more efficient electron conduction. is there.
• electron transfer materials include electron transfer proteins such as cytochrome C and ferredoxin, metal complexes such as osmium (Os) complex and ruthenium (Ru) complex, and organic compounds having an electron transfer function.
• the electrode material of the present invention has an amount of the electron transfer material carried on the porous carbon body. It is preferred to be in excess of the amount of acid reductase.
• a method for supporting the electron transfer substance on the carbon porous body a method similar to the method for supporting the oxidoreductase on the carbon porous body as described above can be employed. Further, the electron transfer substance and the oxidoreductase may be simultaneously supported on the carbon porous body.
• the carbon porous body has pores and at least a part of the oxidoreductase is supported in the pores.
• the amount of the acid reductase supported in the pores of such a carbon porous body is not particularly limited and can be appropriately adjusted according to the design of the target electrode material, and is necessary for desired power generation. Prefer to be in quantity.
• the energy conversion device of the present invention comprises the electrode material of the present invention.
• energy conversion devices include biosensors, fuel cells, and solar cells.
• Examples of such a biosensor include a sensor provided with the electrode material of the present invention in a detection unit for detecting a biological component or the like.
• a biosensor by providing the biosensor with the electrode material of the present invention, electron transfer between the enzyme and the electrode is efficiently performed, so that highly sensitive sensing is possible.
• the manufacturing method of such a nanosensor is not particularly limited, and a known manufacturing method can be appropriately employed.
• the biological components generally mean living organisms included in the category of living organisms and all tissues and cells constituting these, and are further manufactured and processed using such materials as raw materials. Foods etc. are also included in biological components.
• Examples of the fuel cell or the solar cell include those having the electrode material of the present invention on the electrode for the fuel cell or the solar cell.
• Such an electrode for a fuel cell or the solar cell can be obtained, for example, by modifying the electrode material of the present invention on the surface of an electrode core material having a predetermined shape.
• a core material is not particularly limited, and various materials that can be used for electrodes of fuel cells and solar cells can be used.
• the method for obtaining the electrode by modifying the electrode material of the present invention on the surface of the core material is not particularly limited. For example, a suspension obtained by dispersing the electrode material of the present invention in an organic solvent is used as the core material.
• a method in which the electrode material of the present invention is modified on the surface of the core material and a solution in which a porous carbon body is suspended is applied to the surface of the core material, and a carbon porous material is applied to the surface of the core material.
• Examples thereof include a method for producing an electrode by modifying the body and then supporting the oxidoreductase on the strong porous body.
• the solution prepared as described above was further diluted with water to obtain an organic gel while controlling the pore diameter. That is, prepare a solution by diluting the stock solution prepared as described above from 0.1 to 3 times by volume (volume ratio) (Synthesis example 1: dilution factor 0.1 times, synthesis example 2: dilution factor). 0. 5 times, Synthesis example 3: Dilution ratio 1 time, Synthesis example 4: Dilution ratio 3 times, Synthesis example 5: Dilution ratio 2 times), put these solutions in vials, seal tightly, and keep at room temperature for 24 hours The hydrated organic gel was obtained by standing at 50 ° C. for 24 hours and then at 90 ° C. for 72 hours.
• the obtained organic gel was dried as follows. That is, first, a hydrated organic gel was immersed in acetone (Wako Pure Chemicals) as an exchange solvent in order to remove moisture in the organic gel. The water in the gel diffuses into the acetone and the water in the gel The minutes were completely replaced with acetone. At this time, the substitution rate of water was further improved by exchanging acetone as a substitution solvent several times with a new one. Subsequently, the immersion solvent was changed to n-pentane (Wako Pure Chemical Industries), and the solvent exchange-immersion was repeated in the same manner as above until the acetone power in the organic gel—pentane was completely replaced. And the dried organic gel was obtained by air-drying the organic gel solvent-substituted by n-pentane.
• acetone Wi- Pure Chemicals
• the obtained dried organic gel was carbonized as follows to obtain a carbon gel. That is, the carbonization of the gel was carried out by heating the dried organic gel under a nitrogen stream (flow rate 300 mlZmin) at 1000 ° C. The heating time was 6 hours.
• the pore size of the carbon gel obtained in ⁇ 5 is distributed only in the range of 2 to about 40 nm, the pore volume in the range of ⁇ 25% of the average pore diameter is 60% or more, and the average pore diameter It was confirmed that 60% or more of the total pore volume was included in the range of 2 nm, and it was confirmed that the distribution shape force had highly uniform pores.
• the average pore diameters of the carbon gels obtained in Synthesis Examples 1 to 5 were as shown in Table 1.
• the electrode material of the present invention was manufactured using the carbon gel obtained in Synthesis Examples 1 to 4. That is, first, pyrilvinoxydase (BOD) was dissolved in distilled water as an enzyme to prepare a 0.7 mgZml enzyme solution. Next, 0.5 ml of the enzyme solution was added to 12.5 mg of each carbon gel, and gently mixed overnight at 4 ° C to immobilize the enzyme on each carbon gel. Thereafter, the carbon gel on which the enzyme is immobilized is separated and collected from the enzyme solution by centrifugation, and washed three times with 5 ml of distilled water to repeat the electrode material of the present invention (Example 1: Carbon obtained in Synthesis Example 1).
• Example 2 Using the carbon gel obtained in Synthesis Example 2
• Example 3 Using the carbon gel obtained in Synthesis Example 3
• Example 4 Using the carbon gel obtained in Synthesis Example 4 Use).
• the amount of enzyme immobilized was determined by calculating the amount of enzyme in the enzyme solution before and after immobilization based on the absorbance at 280 nm, and the amount of enzyme immobilized on the carbon gel was calculated.
• the electrode materials obtained in Examples 2 to 4 having an average pore diameter larger than the molecular diameter of the enzyme (BOD: 6.4 nm) estimated from the molecular weight of the enzyme almost the entire amount of the enzyme added was immobilized. It is certain that f * i3 ⁇ 4.
• a suspension was prepared by suspending 20 mg of the carbon gel obtained in Synthesis Example 2 in n-methylpyrrolidone (NMP) containing 10% polybutydifluoride.
• NMP n-methylpyrrolidone
• the suspension was spin-coated (1 500 rpm) by 10 1 times on the surface of a ⁇ 6Z ⁇ 3 Dallas carbon (GC) cylindrical electrode to obtain a carbon porous body modified electrode.
• the carbon porous body decorated electrode obtained was immersed in a 5 ⁇ enzyme (BOD) aqueous solution at 4 ° C for a while, then MilliQ After washing with water three times, the BOD is fixed on a carbon porous body (carbon gel) modified on the electrode surface, and the electrode material of the present invention is produced on the surface of the electrode.
• a modified electrode was obtained.
• ADH was applied to the carbon porous body (carbon gel) modified on the electrode surface in the same manner as in Example 5 except that 5 ⁇ alcohol dehydrogenase (ADH) aqueous solution was used instead of 5 ⁇ enzyme (BOD) aqueous solution.
• ADH alcohol dehydrogenase
• BOD 5 ⁇ enzyme
• a carbon porous body (carbon gel) modified on the electrode surface was prepared in the same manner as in Example 5 except that a 5 ⁇ electron transfer protein (cytochrome C) aqueous solution was used instead of the 5 ⁇ enzyme (BOD) aqueous solution.
• the electrode material for comparison was prepared by immobilizing cytochrome C on the electrode surface, and carrying the cytochrome C on carbon gel on the electrode surface, and an electrode having the electrode material for comparison modified on the surface was obtained.
• Example 5 Electric potential of each electrode was measured by electric potential sweep (sweep speed 20mV Z seconds) between electric potentials 0-600mV
• Comparative Example 1 Potential sweep (sweep speed 20mVZ seconds) between electric potentials 0-600mV .
• the cyclic voltamgram obtained using the electrode whose surface was modified with the electrode material obtained in Example 5 is shown in FIG. 1, and the electrode material obtained in Comparative Example 1 was modified on the surface.
• Figure 2 shows the cyclic voltammogram obtained using the electrode.
• Example 6 the electrode material obtained in Example 6 was used on an electrode whose surface was modified, and contained 1% alcohol. 0.1M phosphate buffer (pH 7.0) or no alcohol. Electrical characteristics were measured by cyclic voltamgram method using IM acid buffer (pH 7.0) as electrolyte.
• a comparative electrode was obtained in the same manner as in Example 7 except that carbon black (ketchen black) was used instead of the carbon gel lOmg obtained in Synthesis Example 5. ⁇ Electric property test of electrode>
• the electrolyte solution is cyclically stirred or stirred.
• the electrical characteristics of each electrode were measured by the voltamgram method (potential sweep between potentials 0 and 600 mV (sweep speed 20 mVZ sec)).
• the obtained cyclic voltagram is shown in Fig. 3, and the cyclic voltagram showing the cyclic voltagram shown in Fig. 3 in an enlarged range of 200 to 100 ⁇ is shown in Fig. 4.
• the oxidation current in a stationary state is obtained by using carbon black for the electrode obtained in Example 7 using carbon gel. It was confirmed that it was about 3 times the electrode obtained in Comparative Example 2. In addition, the current value did not change even when the electrode obtained in Comparative Example 2 using carbon black was stirred, whereas in the electrode obtained in Example 7 using carbon gel, By stirring the electrolyte solution and increasing the amount of dissolved oxygen as a reaction substrate, it was confirmed that a larger acid current flows and an oxidation current about 10 times that of the electrode obtained in Comparative Example 2 flows. .
• an electrode capable of obtaining sufficient stability and excellent activity of the carrier component and capable of efficient electron conduction between the carrier and the carrier component. Materials can be provided.
• the electrode material of the present invention is useful as a material used for an electrode of a fuel cell.

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