JP2003257510A - Electrolytic oxidation electrode of sugar, its manufacturing method and battery using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sugar oxidation electrode enabling the chemical energy of the sugar to be used directly for electric energy and a battery using this. <P>SOLUTION: The complex electrode for sugar oxidation at least contains either silver and gold, silver and platinum, or sliver, gold and platinum, by which, a high-efficiency use, that is, a use of two or more electrons out of 24 the sugar has, is made possible at a more cathodic potential. By making such an electrode a negative electrode, a battery with a higher operational voltage can be obtained. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to polysaccharides, disaccharides,
The present invention relates to an electrode for electrochemically oxidizing a sugar such as a monosaccharide, and a battery using the electrode as a negative electrode.

[0002]

2. Description of the Related Art Sugar is an important energy source for animals as well as proteins and lipids. For example, a typical sugar,
When glucose represented by the chemical formula C6H12O6 is completely oxidized, 24 electrons are released per glucose molecule to generate carbon dioxide and water. In the animal body, this 2
Four electrons are used as an energy source. According to thermodynamic calculation, 2872k per mole of glucose
It has an energy of 4.43Wh per 1g of J. This is an energy density of 3.8 Wh / g or more of the weight energy density of metallic lithium used for the negative electrode of a lithium battery known as a high energy density battery.

[0003]

However, the method of utilizing the chemical energy of sugar is to use ATP as heat energy by direct combustion in air or by the action of 12 or more kinds of oxidases in the animal body. The method of using as chemical energy such as is exclusively (Es
sentential Cell Biology, No. 107
P., 1997, published by Garland, Alberts
Et al). As a method of directly utilizing the chemical energy of sugar as electric energy, a method of electrolytic oxidation of sugar is known. Electrodes made of platinum and osmium have been studied (eg Journal of American Chemic
al Society, 123, 8630-863, 200
1 year), in this case, only two of the 24 electrons of sugar can be used, and the sugar utilization efficiency is extremely low. Further, silver or copper electrodes can oxidize sugars of two or more electrons,
Since the oxidation potential is near 0 volt (relative to Ag / AgCl reference electrode) or more than the anode, when a battery is constructed using an oxygen reduction electrode as the positive electrode and a silver or copper electrode as the negative electrode. , Only a low voltage of about 0.2V can be obtained.
Also, the reaction speed is slow and it is difficult to obtain a large output current.

The present invention provides a sugar electrolytic oxidation electrode and a battery for utilizing the chemical energy of sugar directly as electric energy with high efficiency.

[0005]

A method for producing an electrode for electrolytic oxidation of sugar according to the present invention and a battery using the same, which solves the above-mentioned conventional problems, carry silver and at least one of gold and platinum. It is an electrode for electrolytic oxidation of sugar. Furthermore, the electrode for electrolytic oxidation of sugar has a silver content of 50 atom% or more and 95 atom% or less with respect to the amount of the two or three types of metal components. Furthermore, the electrodes are on a conductive substrate,
It is an electrode for electrolytic oxidation of sugar which carries one set of silver and gold, silver and platinum, or silver, gold and platinum. In addition, an electrode for electrolytic oxidation of sugar, including a step of dispersing colloidal particles of the metal component in a solvent, a step of applying the solution obtained in the step to a substrate, and a step of removing all or part of the solvent It is a manufacturing method. The electrode for electrolytic oxidation according to claim 1 or 2, which comprises a positive electrode, a negative electrode, and an electrolyte, wherein the electrolyte contains sugar, and is generated between the positive electrode and the negative electrode due to an oxidation reaction of sugar. A battery that generates electric power.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below.

The sugar electrolytic oxidation electrode of the present invention contains at least silver and gold, silver and platinum, or silver, gold and platinum. It is possible to further oxidize sugar molecules electrolytically oxidized with gold or platinum with silver at a lower potential and at a higher rate.

In the sugar electrolytic oxidation electrode of the present invention, the content of silver is preferably 50 atomic% or more based on the total amount of silver and gold, silver and platinum, or silver, gold and platinum. By doing so, excessive silver atoms can be arranged around the gold or / and platinum atom, and the oxidation product of the sugar oxidized by the gold or / and platinum atom can be promptly added by the silver atom, and It is possible to further oxidize at a more cathodic potential and at a faster rate, resulting in higher efficiency. Suitably, the content of silver is 50 atomic% or more and 95 atomic% or less. 50 atom% above, 95
When it is at most atomic%, the sugar molecule oxidized by gold or platinum can be further oxidized with an efficiency close to 100%, and higher overall oxidation efficiency can be obtained.

Here, it is preferable that silver and gold, silver and platinum, or silver, gold and platinum be supported on a conductive substrate. This facilitates electron transfer between silver, gold, and platinum atoms / particles, resulting in high oxidation efficiency. Here, the loading means chemical reaction, chemical adsorption, and physical adsorption.
Further, it is possible to obtain an electrode with little deterioration in catalytic activity even after long-term use. Examples of such a conductive substrate include platinum, gold, silver, copper, nickel, cobalt, iron, aluminum, titanium, tin, lead, stainless steel, and other metal / alloy materials, artificial graphite, natural graphite, glassy carbon, activated carbon. Carbon materials such as, conductive metal oxide materials such as indium tin oxide (ITO), and conductive polymer materials such as polyaniline, polypyrrole, and polythiophene can be used alone or in combination.

A solution containing silver and gold, silver and platinum, or metal colloid particles containing at least silver, gold and platinum, a polymer dispersant, and a solvent, which is used when preparing the electrode of the present invention,
For example, JP-A-11-80647 and JP-A-11-647
It can be prepared by the method described in Japanese Patent No. 76800. As the solvent for dispersing the metal colloid particles, water, methanol, ethanol, acetone, ethylene glycol, or a hydrophilic solvent such as a mixed solvent thereof, toluene, methyl isobutyl ketone,
Any of lipophilic solvents such as butyl carbitol or a mixed solvent thereof can be used. As the polymer dispersant, a commercially available product described in the above-mentioned published patent can be used.

The sugar used here is not particularly limited, but simple substances such as glucose, mannose, galactose, fructose, glyceraldehyde, dihydroxyacetone, erythrose, ribulose, xylulose, cedoheptulose, ribose, deoxyribose, sorbose, glucosamine and galactosamine. Examples thereof include sugars, disaccharides such as isomaltose, maltose, cellobiose, lactose, raffinose and sucrose, oligosaccharides, and polysaccharides such as starch, glycogen, cellulose, glycoproteins, glycosaminoglycans and glycolipids. Among these, glucose, mannose, galactose, and fructose are preferable because the current efficiency of the electrochemical oxidation reaction in the negative electrode is high. Further, glucose, mannose and galactose are preferable in terms of current efficiency.

The battery according to the present invention is a battery having a positive electrode and a negative electrode provided via an electrolyte as constituent elements, and the negative electrode contains at least silver and gold, silver and platinum, or silver and gold and platinum. An electromotive force is generated between the positive electrode and the negative electrode due to the oxidation reaction of sugar that proceeds in the negative electrode.

Here, the reaction of the positive electrode is a reduction reaction that occurs at a cathodic potential than the oxidation reaction of sugar in the negative electrode, and the electrons extracted from the sugar molecule are electrochemically applied to the positive electrode through an external load. Any reduction reaction can be accepted.

As the reaction of the positive electrode, reduction reaction of water or oxygen, NiOOH, MnOOH, Pb (OH)
2, PbO, MnO2, Ag2O, LiCoO2, LiMn
Reduction reaction of hydroxide or oxide such as 2O4, LiNiO2, reduction reaction of sulfide such as TiS2, MoS2, FeS, Ag2S, reduction reaction of metal halide such as AgI, PbI2, CuCl2, quinone, organic disulfide compound The reduction reaction of organic sulfur compounds such as, and the reduction reaction of conductive polymers such as polyaniline and polythiophene can be used.

Of these, the positive electrode is preferably an oxygen electrode that reduces oxygen. In this case, since a gas containing oxygen can be used as the positive electrode active material, it becomes unnecessary to hold the positive electrode active material in the battery, so that a battery having a high energy density can be configured.

As the oxygen electrode, any substance having an oxygen reducing ability can be used. Examples of such substances include activated carbon, manganese lower oxides such as Mn2O3, platinum, palladium, iridium oxide, platinum ammine complex,
Examples thereof include a cobalt phenylenediamine complex, a metal porphyrin (metal: cobalt, manganese, zinc, magnesium, etc.), and a perovskite oxide such as La (Ca) CoO3 or La (Sr) MnO3.

Any electrolyte can be used as long as it can move anions or / and cations from the positive electrode to the negative electrode or / and from the negative electrode to the positive electrode so that the oxidation / reduction reaction in the positive electrode and the negative electrode can proceed continuously. Any organic substance, inorganic substance, liquid or solid can be used. These electrolytes include water containing ZnCl2 and NH4C.
Metal salts such as l, alkalis such as KOH and NaOH, H3P
L dissolved in an acid such as O4 or H2SO4 or mixed organic solvent of propylene carbonate and ethylene carbonate
IBF4, LiPF6 and other metal salts dissolved therein, ion exchange membranes made of polymer materials such as fluororesin having sulfonic acid group, amide group, ammonium group, pyridinium group and the like, LiBF4, LiCl4, (C4H9) 4NBF4 A polymer electrolyte such as polypropylene oxide or polyethylene oxide in which the above is dissolved can be used.

[0018]

EXAMPLES The present invention will be specifically described below with reference to examples. Although an air electrode is used as the positive electrode in the following examples, the present invention is not limited thereto.

(Example 1) In Example 1, a test electrode 1 containing gold (Au) and silver (Ag), a comparative electrode 1 containing only Au and a comparative electrode 2 containing only Ag were prepared, and electrolytic oxidation characteristics of sugar were prepared. Was evaluated, and a battery was constructed using the test electrode as a negative electrode to generate power.

Preparation of test electrode Hydrosol-Au having an Au concentration of 20.3% by weight was used for 10 times.
It was prepared using 0 mM chloroauric acid aqueous solution, a polymer dispersant, and dimethylaminoethanol as a reducing agent. Hydrosol-Ag having an Ag concentration of 25.1% by weight was prepared using a 150 mM silver nitrate aqueous solution, a polymer dispersant, and triethanolamine as a reducing agent. Each of Hydrosol-Au and Hydrosol-Ag was diluted with ethanol to prepare a solution-Au-1 having an Au concentration of 0.72% by weight and a solution-Ag-1 having an Ag concentration of 0.72% by weight. . Next, solution-Au-1 and solution-Ag-1 were mixed in the same weight, and solution-Au-
Ag-1 was prepared.

Next, the sheet resistance value of the conductive substrate is 1
Glass substrate with ITO film of 0 ohm (size 40x40m
m, ITO thickness 150 to 190 nm) was ultrasonically washed with an aqueous solution containing a surfactant, dried and then ozone washed, and then heated on a heat plate at 120 ° C.

Solution in the reservoir of Artist Air Brush (Handpiece KH-4 (trade name), Kinki Air Co., Ltd.)
Ag-Au-1 (10 g) was put, and the entire amount was sprayed on ITO which was intermittently heated at an argon gas pressure of 0.3 atm.

After spraying the whole amount, it was left on a heat plate for 30 minutes as it was, and then baked in an oven at 300 ° C. for 60 minutes to prepare a test electrode 1 containing Ag and Au. The supported amount of Ag + Au calculated from the weight difference of the ITO glass substrate before spraying and after baking was 0.04 mg / cm2.
Met. Similarly, using the solution-Au-1, the reference electrode 1 having a supported amount of Au of 0.03 mg / cm 2 and the solution-Ag-
2 was used to prepare a reference electrode 2 having an Ag loading of 0.03 mg / cm 2.

Evaluation of Sugar Oxidation Property of Test Electrode Test electrode 1, reference electrode 1 and reference electrode 2 were mounted as working electrode (negative electrode) (23) of the electrolytic cell shown in FIG. 1 and contained 0.62% glucose at 2 mM. A in KOH aqueous solution (26)
The electro-oxidative response of glucose was evaluated by changing the potential at a potential sweep rate of 20 mV / sec in the range of −0.9 V to +0.5 V with respect to the g / AgCl standard electrode (25). The potential is the natural potential of the working electrode (23) (rest pote
6-cycle electrolysis was performed with the change from ntial) toward minus 0.9 V and increasing toward plus 0.5 V when reaching minus 0.9 V as one cycle.

The cell shown in FIG. 1 is a glass container (2
1), rubber plug (22), working electrode (negative electrode) (23) consisting of test electrode or reference electrode, platinum counter electrode (24), Ag / AgCl
It is composed of a standard electrode (25), an electrolytic solution (26) and a positive electrode (27). The area of the working electrode (negative electrode) (23) in contact with the electrolytic solution (26) is 2 cm ² . The current-potential characteristics at the 6th cycle are shown in FIG.

Test electrode 1 containing Ag, Au according to the present invention
Gives an oxidation current response of glucose from around −0.6 V, and this current value corresponds to the current response of the reference electrode 1 containing only Au and the reference electrode 2 containing only Ag and the current response obtained by adding these. It is more than twice as high.

Next, using the same cell shown in FIG. 2, as an electrolyte solution (26), glucose containing 20 mM of 20 mM was added.
Negative electrode (23) and positive electrode (27) using 62% KOH aqueous solution
Fig. 3 shows the current-voltage characteristics when a battery is constituted by and the battery is continuously discharged at a constant current value of 0.02 to 3 mA for 60 seconds. Here, as the positive electrode (27), an air electrode prepared by coating a nickel net with a composition comprising activated carbon, lower manganese oxide (MnOOH), carbon black, and a fluororesin binder was used.

The test battery 1 using the test electrode 1 containing Ag and Au according to the present invention is divided into the comparative battery 1 using the reference electrode 1 containing only Au and the comparison battery 2 using the reference electrode 2 containing only Ag. In comparison, it gives a high voltage and a large output current.
Further, in place of glucose, monosaccharides such as galactose, mannose, sorbose, fructose, disaccharides such as maltose, sucrose, lactose, raffinose, and polysaccharides such as starch were used as the test electrode 1, the reference electrode 1, and the reference electrode 2. As to glucose, the test electrode containing Ag and Au according to the present invention gave significantly improved electrode characteristics and battery characteristics as compared with the reference electrode containing only Au or Ag, as in the case of glucose. .

The reason why the test electrode 1 containing both Au and Ag gives a larger current response than the reference electrodes 1 and 2 is considered as follows. Au coexists with Ag,
Many crystal edge parts (active points) of Au, which are considered to exhibit the original catalytic activity for the oxidation reaction of sugar, are generated, and the catalytic activity can be dramatically increased. Furthermore, by coexisting Au and Ag in the same electrode, the reaction regions of the sugar molecule and Au, the sugar molecule or the oxidation product of the sugar molecule and Ag are overlapped, and the electrolytic oxidation of the sugar molecule can be efficiently performed. That is, the sugar molecule oxidized by Au rapidly moves to the reaction region of the adjacent Ag particles, and is further oxidized by Ag and is quickly removed from the reaction region of Au. For this reason, the reaction region of Au is always kept ready to accept a new sugar molecule, and the oxidation of sugar is promoted as a whole.

Example 2 In Example 2, platinum (Pt) was used.
Test electrode 2 containing silver and silver (Ag), reference electrode 3 containing only Pt
A comparative electrode 2 containing only Ag and Ag was prepared, and the electrolytic oxidation characteristics of sugar were evaluated, and a battery was constructed using the test electrode as a negative electrode to generate electricity.

Preparation of test electrode Hydrosol-Pt having a Pt concentration of 2.1% by weight was mixed with 10
It was prepared using a chloroplatinic acid aqueous solution of mM, a polymer dispersant, and dimethylaminoethanol as a reducing agent. Each of Hydrosol-Pt and Hydrosol-Ag used in Example 1 was diluted with ethanol to give a Pt concentration of 0.72% by weight.
Solution of Pt-1 and a solution having an Ag concentration of 0.72% by weight-
Ag-1 was prepared. Next, Solution-Pt-1 and Solution-Ag-1
Were mixed in the same weight to prepare a solution-Pt-Ag-1.

Next, the sheet resistance value of the conductive substrate is 1
Glass substrate with ITO film of 0 ohm (size 40x40m
m, ITO thickness 150 to 190 nm) was ultrasonically washed with an aqueous solution containing a surfactant, dried and then ozone washed, and then heated on a heat plate at 120 ° C.

Solution in the reservoir of Artist Air Brush (Handpiece KH-4 (trade name), Kinki Air Co., Ltd.)
Pt-Ag-1 (10 g) was added, and the whole amount was sprayed onto ITO heated intermittently at an argon gas pressure of 0.3 atm.

After spraying the whole amount, the test electrode 2 containing Ag and Pt was prepared by leaving it on a heat plate for 30 minutes and baking it in an oven at 300 ° C. for 60 minutes. The loading amount of Pt + Ag calculated from the weight difference of the ITO glass substrate before spraying and after baking was 0.03 mg / cm2.
Met. Similarly, using solution-Pt-1, reference electrode 3 having a Pt loading of 0.04 mg / cm 2, solution-Ag-
2 was used to prepare a reference electrode 2 having an Ag loading of 0.03 mg / cm 2.

Evaluation of Sugar Oxidation Property of Test Electrode Test electrode 1, reference electrode 3 and reference electrode 2 were mounted as working electrodes (negative electrodes) (23) of the electrolytic cell shown in FIG. 1 and contained 0.62% glucose containing 10 mM. Evaluate the electro-oxidative response of glucose by changing the potential in an aqueous KOH solution (26) against the Ag / AgCl standard electrode (25) at a potential sweep rate of 20 mV / sec in the range of minus 0.9 V to plus 0.1 V. did. The potential is the natural potential of the working electrode (23) (rest po
6 cycles of electrolysis was performed, with one cycle being the change from the (tential) toward minus 0.9V and increasing toward minus 0.9V when reaching minus 0.9V.
The current-potential characteristic at the 6th cycle is shown in FIG.

Test electrode 2 containing Ag, Pt according to the present invention
Gives an oxidation current response of glucose from around −0.8V, and this current value increases as the potential goes in the positive direction, and gives a peak value near −0.4V. On the other hand, the reference electrode 3 containing only Pt gives an oxidation current response of glucose from around −0.9V, but when the potential goes in the positive direction, a small peak value near −0.7V, and further around −0.2V. Are given two peak values, which are larger than this. However, these peak values do not exceed the peak value of the test electrode 2 around -4V. The comparison electrode 2 containing only Ag is 1/50 to 100 times smaller than the test electrode 2 and the comparison electrode 3 in the potential range of minus 0.9 V to plus 0.1 V. Even if the response is added to the response of the reference electrode 3, the magnitude of the response of the reference electrode 3 hardly changes.

Next, using the same cell as shown in FIG. 1, as an electrolyte solution (26), glucose containing 20 mM of 0.
Negative electrode (23) and positive electrode (27) using 62% KOH aqueous solution
Fig. 5 shows the current-voltage characteristics when a battery was constituted by and the battery was continuously discharged for 60 seconds at a constant current value of 0.02 to 3 mA. Here, as the positive electrode (27), an air electrode prepared by coating a nickel net with a composition comprising activated carbon, lower manganese oxide (MnOOH), carbon black, and a fluororesin binder was used.

The test battery 2 using the test electrode 2 containing Ag and Pt according to the present invention is the comparison battery 3 using the comparison electrode 3 containing only Pt and the comparison battery 2 using the comparison electrode 2 containing only Ag. In comparison, it gives a high voltage and a large output current.
Further, instead of glucose, monosaccharides such as galactose, mannose, sorbose, fructose, disaccharides such as maltose, sucrose, lactose, raffinose, and polysaccharides such as starch were used as the test electrode 2, the reference electrode 3, and the reference electrode 2. As to glucose, the test electrode containing Ag and Pt according to the present invention gave significantly improved electrode characteristics and battery characteristics as compared with the reference electrode containing only Pt or Ag. .

The reason why the test electrode 2 containing both Pt and Ag gives a larger current response than the reference electrodes 3 and 2 is considered as follows. Pt has the property that the catalytic active site is temporarily covered by carbon monoxide (CO) generated by the oxidation reaction of sugar, and the activity is reduced. This is
It clearly appears in the current-potential characteristics of the reference electrode 3 containing only Pt shown in FIG. When the potential is swept in the cathode direction from plus 0.1 V to minus 0.9 V, a large spike-shaped oxidation current flows. This oxidation current flows because CO that has covered the active point of Pt is removed and the active point is revived. On the other hand, in the test electrode 2 containing Pt and Ag, a slight increase in the oxidation current was observed, but a large spike-shaped current was not observed, and the active points of Pt were difficult to be covered with CO. I understand. The present inventor maintains high activity of Pt because Ag coexisting with Pt effectively removes CO generated during the oxidation reaction of sugar from the surface of Pt by Ag adjacent to Pt. I believe. Further, as in the case where Au and Ag coexist, the coexistence of Pt and Ag in the same electrode causes the reaction regions of the sugar molecule and Pt, the sugar molecule or the sugar molecule oxidation product and Ag to overlap with each other, and the sugar is efficiently added. It is possible to carry out electrolytic oxidation of molecules. That is, the sugar molecule that has been oxidized by Pt quickly moves to the reaction region of the adjacent Ag particles, and is further oxidized by Ag and is quickly removed from the reaction region of Pt. Therefore, the reaction region of Pt is always kept in a state prepared to accept a new sugar molecule, and the oxidation of sugar is promoted as a whole.

(Example 3) In Example 3, platinum (Pt) was used.
A test electrode 3 containing silver (Ag) and gold (Au) was prepared, the electrolytic oxidation characteristics of sugar were evaluated, and a battery was constructed using the test electrode as a negative electrode to generate electricity.

Preparation of Test Electrode The hydrosol-Ag and hydrosol-Au used in Example 1 and the hydrosol-Pt used in Example 2 were diluted with ethanol to obtain a Ag concentration of 0.72% by weight. Solution-Ag-1
And a solution-Au-1 with an Au concentration of 0.72% by weight and a solution-Pt-1 with a Pt concentration of 0.72% by weight, each containing 1 Pt.
A solution-Pt-Au-Ag-1 was prepared by mixing 0 g, 10 g of Au, and 20 g of Ag.

Next, the sheet resistance value of the conductive substrate is 1
Glass substrate with ITO film of 0 ohm (size 40x40m
m, ITO thickness 150 to 190 nm) was ultrasonically washed with an aqueous solution containing a surfactant, dried and then ozone washed, and then heated on a heat plate at 120 ° C.

Solution in the reservoir of Artist Air Brush (Handpiece KH-4 (trade name), Kinki Air Co., Ltd.)
Pt-Au-Ag-1 (10 g) was added, and the total amount was about 20 c on ITO that was intermittently heated at an argon gas pressure of 0.3 atm.
Sprayed while repeatedly swinging from left to right from above. After spraying the whole amount, it was left on a heat plate for 30 minutes as it was, and then baked in an oven at 300 ° C. for 60 minutes to prepare a test electrode 3 containing Ag, Au, and Pt. The loading amount of Pt + Au + Ag calculated from the weight difference of the ITO glass substrate before spraying and after baking was 0.04 mg /
It was cm2.

Evaluation of sugar oxidation property of test electrode The test electrode 3 is the working electrode (negative electrode) of the electrolytic cell shown in FIG.
It is attached as (23) and contains glucose at 10 mM.
62% KOH aqueous solution (26) in Ag / AgCl standard electrode (2
In contrast to 5), the potential was changed at a potential sweep rate of 20 mV / sec in the range of minus 0.9 V to plus 0.1 V, and the electrolytic oxidation response of glucose was evaluated. The electric potential decreases from the natural potential (rest potential) of the working electrode (23) toward minus 0.9V, and when it reaches minus 0.9V, increases toward plus 0.1V as one cycle. I went. 6th cycle current-
The potential characteristics are shown in FIG.

Test electrode 3 containing Ag, Au, Pt according to the invention
Gives an oxidation current response of glucose from around −0.7V, and this current value increases as the potential goes in the positive direction, and gives a peak value near −0.2V. In the test electrode 3, a large spike-shaped oxidation current does not flow when the electric potential is swept in the cathode direction from plus 0.1 V to minus 0.9 V as seen in the electrode containing only Pt. , CO poisoning hardly occurs.

Next, using the same cell as shown in FIG.
As an electrolytic solution (26), a glucose solution containing 20 mM of glucose was added.
Negative electrode (23) and positive electrode (27) using 62% KOH aqueous solution
Fig. 5 shows the current-voltage characteristics when a battery was constituted by and the battery was continuously discharged for 60 seconds at a constant current value of 0.02 to 3 mA. Here, as the positive electrode (27), an air electrode prepared by coating a nickel net with a composition comprising activated carbon, lower manganese oxide (MnOOH), carbon black, and a fluororesin binder was used.

The test battery 3 using the test electrode 3 containing Ag, Au and Pt according to the present invention gives a high voltage and a large output current. Further, instead of glucose, monosaccharides such as galactose, mannose, sorbose, fructose, disaccharides such as maltose, sucrose, lactose, raffinose, and polysaccharides such as starch were used as the test electrode 2, the reference electrode 3, and the reference electrode 2. Was characterized in that, as in the case of glucose, A
Test electrode 3 containing g, Au, Pt and test electrode 4 containing Pt, Au gave significantly improved electrode properties as well as battery properties.

The reason why the test electrode 3 containing Pt, Au and Ag gives a large current response will be considered as follows. Pt is carbon monoxide (C
O) has the property that the catalytically active sites are temporarily covered and the activity decreases. This is clearly shown in the current-potential characteristics of the reference electrode 3 containing only Pt shown in FIG. When the potential is swept in the cathode direction from plus 0.1 V to minus 0.9 V, a large spike-shaped oxidation current flows. This oxidation current flows because CO that has covered the active point of Pt is removed and the active point is revived. On the other hand, in the test electrode 3 containing Pt, Au, and Ag, no large spike-shaped current was observed, and Pt
It can be seen that the active points of are hard to be covered with CO. The present inventor has found that the coexistence of Ag, Au, and Pt effectively removes CO generated in the course of the oxidation reaction of sugar from the Pt surface so that Ag adjacent to Pt or Ag and Au can be effectively removed from the Pt surface. It is believed that the high activity of is maintained.
Furthermore, by coexisting Pt, Ag, and Au in the same electrode, the reaction regions of the sugar molecule and Pt, the sugar molecule or the oxidation product of the sugar molecule, and Ag and Au are overlapped, and the electrolytic oxidation of the sugar molecule is efficiently performed. be able to. That is, sugar molecules that have been oxidized by Pt are
It rapidly moves to the reaction region of the u particles, is further oxidized by Ag and Au, and is quickly removed from the reaction region of Pt. Therefore, the reaction region of Pt is always kept in a state prepared to accept a new sugar molecule, and the oxidation of sugar is promoted as a whole.

[0049]

The electrode for sugar electrolytic oxidation of the present invention comprises silver and gold,
An electrode containing at least silver and platinum, or at least silver, gold and platinum, which results in high efficiency
It is possible to use two or more electrons among the individual electrons with a more cathodic potential. By using such an electrode as a negative electrode, a battery having a higher operating voltage can be obtained. According to the present invention, the chemical energy of sugar can be effectively utilized directly as electric energy.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a cell used for production of test electrodes, evaluation of sugar oxidation characteristics, and evaluation of battery characteristics in an example of the present invention.

FIG. 2 is a current-potential characteristic diagram of a test electrode and a reference electrode in Example 1 of the present invention.

FIG. 3 is a current-voltage characteristic diagram of a test battery and a comparative battery in Example 1 of the present invention.

FIG. 4 is a current-potential characteristic diagram of a test electrode and a reference electrode in Example 2 of the present invention.

FIG. 5 is a current-voltage characteristic diagram of a test battery and a comparative battery in Example 2 of the present invention.

FIG. 6 is a current-potential characteristic diagram of a test electrode in Example 3 of the present invention.

FIG. 7 is a current-voltage characteristic diagram of a test battery in Example 3 of the present invention.

[Explanation of symbols]

21 glass container 22 Rubber stopper 23 Working electrode (negative electrode) 24 Platinum counter electrode 25 Ag / AgCl standard electrode 26 Electrolyte 27 Positive electrode

Claims (5)

[Claims] 1. An electrode for electrolytic oxidation of sugar, which carries silver and at least one of gold and platinum. 2. The electrode for electrolytic oxidation of sugar according to claim 1, wherein the content of silver is 50 atom% or more and 95 atom% or less with respect to the amount of the two or three types of metal components. . 3. The sugar according to claim 1, wherein the electrode has one of silver and gold, silver and platinum, or silver, gold and platinum supported on a conductive substrate. Electrolytic oxidation electrode. 4. A method comprising: a step of dispersing colloidal particles of the metal component in a solvent; a step of applying the solution obtained in the step to a substrate; and a step of removing all or part of the solvent. The method for producing an electrode for electrolytic oxidation of sugar according to claim 1. 5. A positive electrode, a negative electrode, and an electrolyte are constituent elements,
The electrode for electrolytic oxidation according to claim 1 or 2, wherein the electrolyte contains sugar, and an electromotive force is generated between the positive electrode and the negative electrode due to an oxidation reaction of sugar.