HK1219119B - Electrochemical process and system for producing glucose - Google Patents

Description

Electrochemical method and system for producing glucose

Field of the Invention

The present invention relates to methods and systems for producing glucose, and in particular, the present invention relates to producing glucose using water, carbon dioxide, electromagnetic energy, melanin, a melanin precursor, a melanin derivative, a melanin analog, or a melanin variant.

Background of the Invention

Glucose is a monosaccharide with the general chemical formula C ₆ H ₁₂ O ₆ . Glucose is a fundamental molecule of the food chain and a major source of energy for many organisms. One well-studied process that produces glucose is photosynthesis in plants.

Generally speaking, photosynthesis is the process of converting light energy into chemical energy. More specifically, through photosynthesis, plants use light energy to convert carbon dioxide ( _CO2 ) and water ( _H2O ) into oxygen ( _O2 ) and glucose. Another key component of this process is the pigment known as chlorophyll. Chlorophyll initiates photosynthesis by absorbing light energy, or photons. For each absorbed photon, chlorophyll loses an electron, generating an electron flow that subsequently generates the necessary energy to catalyze the splitting of water into hydrogen ions or protons (H ⁺ ) and _O2 . The resulting proton gradient is used to generate chemical energy in the form of adenosine triphosphate (ATP). This chemical energy is then used to convert carbon dioxide and water into glucose.

Similar to chlorophyll, melanin is also a pigment. Melanin is composed of nitrogen, oxygen, hydrogen and carbon, but its exact structure has not been fully elucidated. Melanin is ubiquitous in nature, and its synthesis method is known in the literature. For many years, melanin itself had no biological or physiological function, except that it was considered a simple sunscreen with a low protection factor equivalent to a 2% copper sulfate solution. Melanin is also considered the blackest molecule because it can absorb energy of almost all wavelengths, but it does not seem to release any energy. This property is unique to melanin and contradicts the laws of thermodynamics because other compounds that can absorb energy (especially pigments) can release some of the absorbed energy. The electronic properties of melanin have therefore become the focus of attention for quite some time. However, melanin is one of the most stable compounds known to humans, and for a long time, it seemed that melanin could not catalyze any chemical reactions.

In recent years, researchers have discovered the inherent property of melanin, which absorbs energy and uses it to split and reconstruct water molecules. Therefore, melanin absorbs electromagnetic energy of all wavelengths (including visible and invisible light energy) and dissipates this absorbed energy through water splitting and subsequent reconstitution. The photoelectrochemical process of splitting water into hydrogen and oxygen using melanin, its analogs, precursors, derivatives, or variants is described in U.S. Patent Application No. US 2011/0244345.

Without wishing to be bound by any theory, it is believed that melanin reacts as shown in Scheme 1 below.

Upon absorbing electromagnetic energy (visible or invisible), melanin catalyzes the splitting of water into diatomic hydrogen (H ₂ ), diatomic oxygen (O ₂ ), and electrons (e). Although the splitting of water into hydrogen and oxygen consumes energy, the reaction is reversible, and in the reverse reaction, the oxygen atoms are reduced by diatomic hydrogen and reformed into water molecules, releasing energy.

Therefore, melanin can convert light energy into chemical energy, similar to how plants use chlorophyll to convert light energy into chemical energy during photosynthesis. Therefore, based on this similar effect, we have named this process "artificial photosynthesis." However, the water-splitting reaction in which melanin participates differs from that in which chlorophyll participates in at least two important aspects. First, chlorophyll cannot catalyze the reverse process of water molecule reconstruction. Second, the water-splitting reaction catalyzed by chlorophyll can only occur in living cells and requires visible light with a wavelength range of 400nm-700nm. Therefore, the subsequent production of glucose can only occur within living cells. In contrast, melanin can use any form of electromagnetic energy, especially light energy (visible or invisible) with a wavelength between 200nm and 900nm, to hydrolyze and reconstitute water molecules outside of living cells.

SUMMARY OF THE INVENTION

It has now been discovered that upon absorbing electromagnetic energy, such as invisible or visible light energy, melanin can break down or reconstitute water molecules and subsequently catalyze the reaction of carbon dioxide (CO ₂ ) and water to produce glucose.

The present invention relates to electrochemical methods and systems that utilize melanin, melanin precursors, melanin derivatives, melanin analogs, and melanin variants to generate glucose from carbon dioxide ( _CO2 ) and water. According to embodiments of the present invention, melanin can be utilized to generate glucose from carbon dioxide ( _CO2 ) and water, requiring only an additional electromagnetic energy source, such as invisible or visible light energy, gamma rays, X-rays, ultraviolet light, infrared radiation, microwaves, and radio waves. Unlike chlorophyll's ability to convert light energy into chemical energy, which is then used to produce glucose through photosynthesis within cells, melanin can generate glucose electrochemically outside of living cells. Therefore, to date, this method of producing glucose has not been able to be replicated in a laboratory.

In a general aspect, the present invention relates to an electrochemical method for producing glucose (C ₆ H ₁₂ O ₆ ). According to an embodiment of the present invention, the electrochemical method comprises reacting water with carbon dioxide gas dissolved therein in the presence of at least one melanin substance and an electromagnetic energy source. The at least one melanin substance is selected from the group consisting of melanin, a melanin precursor, a melanin derivative, a melanin analog, and a melanin variant. Because melanin can absorb electromagnetic energy and convert it into usable chemical energy, glucose can be produced according to the electrochemical method of the present invention without the need for an external current. In a preferred embodiment, the electrochemical method of the present invention is a photoelectrochemical method, and the electromagnetic energy source is photoelectric energy selected from visible light and invisible light, with a wavelength in the range of 200 nm to 900 nm.

In another general aspect, the present invention relates to an electrochemical method for producing _{CnH2nO species} , where n represents an integer. In a preferred embodiment, n represents 1, 2, 3 _, 4, 5, or 6 _, such that _{the CnH2nO} species produced by the method of the present invention is a glucose precursor or glucose itself. According to an embodiment of the present invention, the electrochemical method comprises reacting water with dissolved carbon dioxide gas in the presence of at least one melanin substance and an electromagnetic energy source. Preferably, the photoelectric energy is selected from visible and invisible light energy having a wavelength in the range of 200 nm to 900 nm.

In another aspect, the present invention relates to a system for producing glucose and _{CnH2nOn species} using water, carbon dioxide, melanin, and _an electromagnetic energy source. According to an embodiment of the present invention, the system for producing glucose by electrochemical methods comprises:

(i) a reaction chamber for receiving water and _CO2 gas dissolved therein, and at least one melanin substance, wherein the at least one melanin substance is selected from the group consisting of melanin, a melanin precursor, a melanin derivative, a melanin analog, and a melanin variant; and

(ii) an electromagnetic energy source, whereby electromagnetic energy is transmitted into the reaction chamber and absorbed by the melanin substance.

In embodiments of the present invention, the system for producing glucose does not require complex operation or setup, requiring only a container for receiving water, dissolved _CO₂ gas, and at least one melanin substance, and an electromagnetic energy source. The container provides sufficient energy to the at least one melanin substance to catalyze the cleavage and reconstruction of water molecules and subsequently form glucose. In a preferred embodiment, the electromagnetic energy source delivers visible or invisible light energy with a wavelength of 200 nm to 900 nm into the reaction chamber.

The details of one or more embodiments of the invention are set forth in the description below. Other features and advantages will be apparent from the following detailed description and the appended claims.

Detailed Description of the Invention

All patents and publications mentioned herein are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art to which the present invention relates. Otherwise, certain terms used herein have the meanings as set forth in the specification.

It is noted that as used herein and in the appended claims, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise.

As used herein, the term "water electrolysis" refers to a method for splitting water molecules into oxygen and hydrogen. As used herein, a "water electrolysis material" refers to a substance that can split water into oxygen and hydrogen. According to an embodiment of the present invention, melanin substances, including melanin (natural and synthetic), melanin precursors, melanin derivatives, melanin analogs, and melanin variants are all water electrolysis materials.

As used herein, the term "melanin substances" refers to melanin, melanin precursors, melanin derivatives, melanin analogs, and melanin variants, including natural and synthetic melanins, eumelanin, pheomelanin, neuromelanin, polyhydroxyindole, eumelanin, alomelanin, humic acid, fullerens, graphite, polyindolequinones, acetylene black, pyrrole black, indole black, benzence black, black), thiophene, aniline black, hydrated forms of polyquinones, sepiomelanins, dopa black, dopamine black, adrenaline black, catechol black, 4-aminocatechol black, simple straight-chain aliphatic or aromatic compounds; or their precursors as phenols, aminophenols, or diphenols, indole polyphenols, quinones, semiquinones or hydroquinones, L-tyrosine, L-dopamine, morpholine, o-benzoquinone, morpholine, porphyrin black, pterin black, and ommochrome black.

According to an embodiment of the present invention, the electrochemical method for producing glucose comprises reacting water with carbon dioxide gas dissolved therein in the presence of at least one melanin substance and an electromagnetic energy source. Suitable forms of electromagnetic energy for the electrochemical method of the present invention include visible and invisible light, gamma rays, X-rays, ultraviolet light, infrared radiation, microwaves and radio waves. In a preferred embodiment, the electrochemical method of the present invention is a photoelectrochemical method, wherein the electromagnetic energy source is photoelectric energy selected from visible and invisible light (ultraviolet light and infrared radiation).

According to an embodiment of the present invention, the at least one melanin substance is selected from the group consisting of melanin, melanin precursors, melanin derivatives, melanin analogs, and melanin variants. In a preferred embodiment, the at least one melanin substance is selected from natural melanin and synthetic melanin.

According to an embodiment of the present invention, melanin can be synthesized from amino acid precursors of melanin (e.g., L-tyrosine). However, the melanin substances disclosed herein can be obtained by any method known in the art, including chemical synthesis of melanin and isolation of melanin substances from natural sources (e.g., plants and animals).

According to another embodiment of the present invention, the electrochemical method can be carried out in the presence of at least one melanin device. The melanin device includes a substrate and at least one melanin substance, whereby the melanin substance is located on or within the substrate. The melanin substance can be dispersed on the substrate or adsorbed on the substrate. Preferably, the substrate is transparent so as to increase the electromagnetic energy transmitted in the form of light energy, thereby increasing the yield of glucose. The melanin device can include one type of melanin substance, or more than one type of melanin substance. For example, the melanin device used in the present invention may include melanin and eumelanin. According to another embodiment of the present invention, more than one type of melanin device, each device including a different type of melanin substance can be used. For example, a first melanin device including melanin and a second melanin device including eumelanin can be used together in the method for producing glucose described in the present invention.

The purpose of using a melanin device in the electrochemical method of the present invention is to prevent the melanin substance from dissolving in water, dispersing in water, or floating freely in water. The melanin device can ensure that the water maintains transparency and that the melanin is not lost when water or _CO2 is added or glucose is removed. Therefore, the melanin device allows the melanin substance to come into contact with water without dissolving in water. The substrate of the melanin device can be an inert material, including (but not limited to): silica, plastic and glass. The melanin device can be, for example, a melanin/silica plate, which can be made by mixing a cementitious mixture of silica with an aqueous solution of melanin. Preferably, the melanin device used in the present invention is melanin mixed with silica.

According to an embodiment of the present invention, the melanin device can be of any size and shape, including (but not limited to): rod-shaped (cylindrical), plate-shaped, spherical, or cubic. At least one melanin device can be used, but the number of melanin devices or their sizes or shapes are not subject to any restrictions. The reaction rate will be controlled by the size, shape, surface area, amount of melanin substance, and number of melanin devices used in the reaction. In a preferred embodiment, the size, shape, and number of melanin devices are selected based on the expected electrochemical reaction rate. For example, using a larger melanin device will result in a faster rate of glucose production. As another illustrative example, the greater the amount of melanin substance in the melanin device, the faster the rate of glucose production.

In an embodiment of the present invention, the electrochemical process begins when the melanin substance absorbs electromagnetic energy and electrolyzes water into _H2 and _O2 . According to an embodiment of the present invention (intermittent method), carbon dioxide gas is dissolved only once in water before the photoelectrochemical process begins. According to another embodiment of the present invention (continuous method), the photoelectrochemical process also includes continuously dissolving _CO2 gas in water, thereby continuously replenishing _CO2 gas when it is continuously consumed and converted into glucose, and any method suitable for continuously dissolving _CO2 gas in water can be used. For example, _CO2 gas can be continuously injected into water using a tube or conduit connected to an air pump. The tube or conduit can be made of any inert material that is substantially impermeable to _CO2 gas, including (but not limited to): polyethylene.

According to a specific embodiment of the present invention, the method for producing glucose is a photoelectrochemical method that requires a photoelectric energy source. Preferably, the photoelectric energy source is visible light or invisible light with a wavelength of 200nm-900nm. In a more preferred embodiment, the photoelectric energy source is natural light.

According to another embodiment of the present invention, the electrochemical method can be carried out at room temperature (about 25°C), preferably, at a temperature below room temperature and at a temperature of 0°C-25°C, and more preferably, at a temperature of 2°C-8°C. Although lower temperatures can reduce the turnover rate of molecular cracking and reconstruction, maintaining a lower temperature can retain the _CO2 bubbles introduced at the beginning of the method and eliminate the need to continuously inject _CO2 gas into the water. Therefore, using a lower temperature has the main advantage of making the electrochemical method more technically convenient to perform.

The electrochemical method of the present invention further includes a step of separating the glucose obtained from the reaction of carbon dioxide, water, and at least one melanin substance. As an illustrative example, the glucose can be separated by evaporating the aqueous reaction solution. However, the glucose can be determined and measured without the separation step, for example, by spectrophotometry.

The present invention also relates to an electrochemical method for producing _{CnH2nO species} , wherein n represents an integer. Preferably, n is 1, 2, 3, 4, 5, or 6 _, such that _{the CnH2nO species} is a glucose precursor or glucose itself. According to an embodiment of the present invention, the electrochemical method for producing _{CnH2nO species} can be the same as the method for producing glucose, _comprising reacting water with dissolved carbon dioxide gas in the presence of at least one melanin substance and an electromagnetic energy source. Preferably, the electromagnetic energy source is photoelectric energy selected _from visible light and invisible light (ultraviolet light and infrared radiation). Other embodiments of the method for producing _{CnH2nO species} described herein can be the same as the electrochemical method for producing glucose described herein. Preferably, the electrochemical method _for producing _{CnH2nO species} is a photoelectrochemical method.

In embodiments of the present invention, melanin can utilize electromagnetic energy to produce glucose, glucose precursors, and other _{CnH2nO species} from _CO2 and water. The precise mechanism is not yet fully understood. Without wishing _to be bound by any theory, it is believed that melanin absorbs electromagnetic energy, facilitating the conversion of low-energy electrons into high-energy electrons. The high-energy electrons are transferred via mobile electron carriers within the melanin. This electron transfer releases energy and establishes a proton gradient sufficient to trigger the splitting of water into diatomic hydrogen ( _H2 ) and diatomic oxygen ( _O2 ), simultaneously releasing four high-energy electrons. Consequently, melanin releases _H2 and _O2 molecules, as well as a diffusion-controlled flow of high-energy electrons in all directions. The released hydrogen and high- _energy electrons have different energy types, and both types of energy are believed to play a role in the conversion of _CO2 and water into glucose and other _{CnH2nO species} . Although the splitting of water into _H2 and _O2 requires energy, the reaction is reversible, and the reduction of _O2 with _H2 , thereby reconstructing water molecules, releases energy. Therefore, after the water molecule is broken down, it must be reconstructed to provide energy for the reaction in which _CO2 and water fuse to produce glucose.

Many factors can affect the rate and efficiency of the electrochemical methods for producing glucose described in embodiments of the present invention. These factors include, but are not limited to, the energy released by the splitting and reconstitution of water molecules, the entropy of dissolved _CO₂ gas, the amount of dissolved _CO₂ gas, temperature, pressure, the wavelength of the electromagnetic energy supplied to the reaction, and the amount of electromagnetic energy absorbed by the melanin material.

In a preferred embodiment of the present invention, the electrochemical method for producing glucose is carried out under sterile conditions, which means that the reaction is substantially sterile. Since bacteria can consume glucose, the presence of bacteria will reduce the amount of glucose produced by the electrochemical method of the present invention. Based on the disclosure of the present invention, the reaction can be sterilized by any known method, including (but not limited to): filter sterilization and high temperature sterilization.

The dissociation and reconstitution of water molecules to generate energy (which is subsequently used in the reaction to produce glucose from carbon dioxide and water) can be catalyzed by at least one melanin substance, wherein the at least one melanin substance is the sole water-electrolyzing material present in the reaction. Therefore, in one specific embodiment of the present invention, the at least one melanin substance is the sole water-electrolyzing material used in the electrochemical method for producing glucose. In a preferred embodiment, melanin (synthetic or natural) is the sole water-electrolyzing material used in the method for producing glucose.

Another aspect of the present invention provides a system for producing glucose using an electrochemical method. According to an embodiment of the present invention, the system includes a reaction chamber and an electromagnetic energy source. As used herein, the term "reaction chamber" refers to any container that can receive and hold water and carbon dioxide gas dissolved in the water. The reaction chamber can be of any shape and can be made of any suitable material, including but not limited to plastic, glass, and any other material that allows electromagnetic energy of the desired wavelength to be transmitted into the reaction chamber, thereby allowing the electrochemical reaction to proceed. The material of the reaction chamber is preferably a transparent material to allow the transmission of visible light. The material of the reaction chamber is also preferably a material that is substantially impermeable to carbon dioxide.

In another embodiment, the reaction chamber is a sealed reaction chamber, which is sealed to prevent carbon dioxide gas from escaping the reaction chamber, and the reaction chamber can be made of any suitable material as described above. Preferably, the reaction chamber is in a sealed state. The reaction chamber receives water and _CO2 gas dissolved therein, and at least one melanin substance. The at least one melanin substance is selected from the group consisting of melanin, melanin precursors, melanin derivatives, melanin analogs, and melanin variants, and is preferably melanin (synthetic or natural). In another embodiment of the present invention, the system includes at least one melanin substance as part of at least one melanin device, which includes a substrate and a melanin substance as discussed above. Preferably, the melanin device includes melanin (natural or synthetic) and silica.

The system of the present invention is preferably sterile and free of bacteria. The system, including one or more of its components (reaction chamber, conduit, etc.), can be sterilized using sterilization or disinfection methods known in the art, such as high temperature, chemical, radiation, pressure, or filtration methods.

According to an embodiment of the present invention, the electromagnetic energy source provides energy to the reaction chamber, which is then absorbed by the melanin substance. In a preferred embodiment, the electromagnetic energy source provides invisible or visible light energy to the reaction chamber, with a wavelength between 200nm and 900nm.

According to another embodiment of the present invention, the system further comprises a device for continuously injecting _CO₂ gas into the reaction chamber. The device may be, for example, an air pump. The device may be connected to the reaction chamber by a tube or pipe. If the reaction chamber is closed, the device is preferably connected in such a way that the sealed reaction chamber remains sealed to prevent the _CO₂ gas from escaping. Therefore, using a sealed reaction chamber has the advantage of not requiring continuous injection of carbon dioxide into the reaction chamber, provided that the container is sufficiently sealed to prevent the carbon dioxide gas from escaping.

According to an embodiment of the present invention, the system for producing glucose by electrochemical method can also be used to produce _{CnH2nOn -} type substances. Preferably, the _CnH2nOn - _type substances are glucose precursors, wherein _n represents 1, 2 _, 3, 4, or 5.

According to an embodiment of the present invention, the electrochemical method and system for producing glucose, in addition to _CO2 gas dissolved in water, only requires the presence of melanin substance and electromagnetic energy (preferably, photoelectric energy, more preferably, light energy), and is therefore environmentally friendly because, in addition to the energy source that requires the presence of the natural environment, no external energy source is required. In addition, no complicated setup or maintenance is required. The only maintenance that requires is the replacement of water and dissolved _CO2 gas once _CO2 is consumed and converted into glucose. Since melanin is one of the most stable molecules known to mankind, with a half-life estimated to be on the order of millions of years, the melanin substance or melanin device can be used for decades before needing to be replaced.

In a preferred embodiment, in the system, the at least one melanin substance is melanin (natural or synthetic). In another preferred embodiment, melanin is the only water-electrolyzing material present in the system.

According to embodiments of the present invention, the electrochemical methods and systems for producing glucose have at least two important applications. First, as described above, they produce glucose, a building block of the food chain. Second, they are related to the control of atmospheric _CO₂ . According to embodiments of the present invention, the production of glucose requires the consumption of _CO₂ . Therefore, the present invention also provides a method for reducing atmospheric _CO₂ levels.

Carbon dioxide (CO ₂ ) is the primary greenhouse gas produced by human activities, and atmospheric CO ₂ concentrations are increasing at an accelerating rate, contributing to global warming and climate change. Although a safe upper limit for atmospheric CO ₂ has been set at 350 parts per million (ppm), atmospheric CO 2 levels have remained above this limit since early 1988. Furthermore, paleoclimate evidence and ongoing climate change suggest that CO 2 levels need to be reduced to preserve the Earth's state to which life has adapted.

Furthermore, calculations by NASA researchers show that despite unusually low solar activity between 2005 and 2010, Earth continues to absorb more energy than it returns to space. Therefore, climate stabilization requires not only restoring Earth's energy balance but also reducing _CO₂ levels. In other words, Earth needs to radiate back into space the same amount of energy it absorbs from the Sun to slow the greenhouse effect.

Therefore, a novel approach to controlling atmospheric _CO₂ levels and consuming absorbed solar energy is urgently needed. In the photoelectrochemical process described in embodiments of the present invention, only light energy and at least one melanin substance, such as melanin (natural or synthetic), a melanin analog, or a melanin precursor, are required to convert _CO₂ and water into glucose. Thus, in the photoelectrochemical process of the present invention, _{both CO₂} and solar energy are consumed in the production of glucose, which helps to reduce _CO₂ levels while simultaneously utilizing absorbed solar energy.

Example

Example 1 Melanin catalyzes the dissociation and reconstruction of water molecules

Two 1-liter sealed polyethylene terephthalate (PET) containers (sealed reaction chambers) were prepared under sterile conditions. Each container contained 1 liter of pure water. _CO₂ gas was dissolved in the water in each container at an initial pressure of 5 atmospheres. Melanin mixed with silica was placed in one of the two containers. Both containers were exposed to visible light for 6 weeks and incubated at a temperature of approximately 2°C to 8°C (35.6°F to 46.4°F).

After 5 days, deformation of the plastic packaging was observed in the container containing the melanin mixed with silica. In contrast, after 6 weeks of exposure to visible light, no visible deformation was observed in the plastic packaging without any container containing the melanin mixed with silica.

The experimental results support the idea that melanin has an intrinsic ability to dissociate and reconstitute water molecules under light energy. This dissociation and reconstitution of water molecules creates a vacuum, which manifests as deformation of the plastic packaging of a sealed container containing only melanin. The energy generated by the melanin-catalyzed cleavage and reconstitution of water molecules can then be used to convert carbon dioxide and water into glucose.

Example 2 Glucose production from CO ₂ dissolved in water, melanin and light energy

10 airtight, 3L sealed containers (sealed reaction chambers) made of polyethylene are formed under sterile conditions. Each container holds 1800mL of pure water. At a pressure of approximately 2.20PSI, a sufficient amount of _CO2 is dissolved in each container so that many _CO2 bubbles can be easily observed. Five of the containers serve as a control group, which do not contain a melanin device, and the other five containers serve as an experimental group. For the experimental group, a silica plate mixed with melanin is placed at the bottom of each container. The melanin/silica plate is made by mixing a cemented mixture of silica with an aqueous solution of melanin. The melanin used is chemically synthesized in the laboratory.

The containers for both the control and experimental groups were placed in a refrigerator and kept at a temperature of 2°C to 8°C (35.6°F to 46.4°F) for four weeks. The purpose of keeping the containers in the refrigerator was to preserve the _CO₂ gas initially dissolved in the water. This eliminated the need for continuous manipulation of the containers, which required dissolving _CO₂ in the water continuously or in batches during the experiment. Because the refrigerator consisted of metal walls, the energy source for the containers was primarily invisible light within the refrigerator. The containers remained sealed throughout the experiment, and _CO₂ bubbles were still observed in the control group during the four weeks of incubation, indicating that the container seal was adequate.

Observe the dissolved _CO₂ bubbles daily. After the first week, _CO₂ bubbles were visible in all control group containers and showed no change from the beginning of the experiment. On the other hand, in all experimental group containers, the dissolved _CO₂ bubbles disappeared completely after a few hours, indicating that the carbon dioxide was consumed in the presence of melanin alone. Even though the _CO₂ bubbles in the experimental group containers disappeared within a few hours, the experiment was continued for another 4 weeks to determine if any gas products or precipitates were formed. After the fourth week, under sterile conditions, the seals of the experimental group containers and the control group containers were opened and a 10 mL water sample was taken from each container. It is also important to note that at the end of the fourth week, there was no change in the _CO₂ in the control group containers compared to the beginning of the experiment.

10mL water samples taken from the control and experimental containers were clear and odorless. For the experimental group, no precipitation was observed in any of the samples, indicating that the melanin had not dispersed from the melanin/silica plate. Other parameters, including density, pH, and glucose concentration, were measured for each sample.

The glucose concentration in each sample was determined spectrophotometrically using a standardized glucose oxidase (GOD) assay. Briefly, each sample was treated with glucose oxidase to oxidize glucose, producing gluconic acid and hydrogen peroxide. In the presence of peroxidase, hydrogen peroxide oxidatively couples with 4-amino-antipyrine (4-AAP) and phenol to produce quinoneimine, a red dye. The absorbance of quinoneimine at 505 nm is proportional to the glucose concentration, and this absorbance is then measured and used to determine the glucose concentration in the sample. The results are listed in Table 1 below.

Table 1

control group Experimental group 1.005 1.000 pH 7.5 6.5 Glucose concentration (mg/dL) 0.0 0.1-0.12

The above experimental results show that glucose can be produced using carbon dioxide and water, only melanin and electromagnetic energy (such as invisible light) are needed.

It should be understood that those skilled in the art may make modifications to the above embodiments without departing from the broad concepts of the present invention. Therefore, it should be understood that the present invention is not limited to the specific embodiments disclosed, but is intended to cover such modifications as fall within the spirit and scope of the present invention as defined by the appended claims.

Claims (16)

1. An electrochemical method for producing glucose, characterized in that the method comprises: reacting water with carbon dioxide gas dissolved therein in the presence of at least one melanin device and an electromagnetic energy source to produce glucose, wherein the at least one melanin device comprises a substrate and melanin, the melanin being located within the substrate, thereby preventing the melanin from being dispersed in the water. 2. The electrochemical method according to claim 1, wherein the electrochemical method is a photoelectrochemical method, and the electromagnetic energy source is visible or invisible light energy with a wavelength between 200 nm and 900 nm. 3. The electrochemical method as described in claim 1 further includes continuously dissolving carbon dioxide gas in water. 4. The electrochemical method according to claim 1, wherein the substrate of the at least one melanin device is silicon dioxide, thereby forming a mixture of melanin and silicon dioxide. 5. The electrochemical method according to claim 1, wherein the method is carried out at a temperature of 0°C–25°C. 6. The electrochemical method according to claim 1, wherein the melanin is selected from natural melanin and synthetic melanin. 7. The electrochemical method according to claim 1, wherein the melanin is the only water-electrolyzable material used in the method. 8. An electrochemical method for producing glucose and a glucose precursor having the general formula C _{_n}H _{_2n O} _n, wherein n represents 2, 3, 4, 5, or 6, characterized in that the method comprises: reacting water with carbon dioxide gas dissolved therein in the presence of at least one melanin device and an electromagnetic energy source, thereby producing glucose or the glucose precursor, wherein the at least one melanin device comprises a substrate and melanin, the melanin being located within the substrate, thereby preventing the melanin from being dispersed in the water. 9. The electrochemical method according to claim 8, wherein the electrochemical method is a photoelectrochemical method, and the electromagnetic energy source is visible or invisible light energy with a wavelength between 200 nm and 900 nm. 10. The electrochemical method according to claim 8, wherein the melanin is selected from natural melanin and synthetic melanin. 11. A system for producing glucose and a glucose precursor having the general formula C _{_n} H _{_2n} O_{_n} by an electrochemical method, characterized in that n represents 2, 3, 4, 5, or 6, said system comprising: (i) a reaction chamber for receiving water and dissolved _CO2 gas therein, and at least one melanin device comprising a substrate and melanin, the melanin being located within the substrate, thereby preventing the melanin from dispersing in the water; and (ii) An electromagnetic energy source, thereby allowing electromagnetic energy to be transferred into the reaction chamber and absorbed by at least one melanin substance. 12. The system of claim 11, wherein the reaction chamber is connected to a device for continuously injecting _CO2 gas into the reaction chamber. 13. The system as described in claim 11, wherein the electromagnetic energy source is invisible or visible light energy with a wavelength between 200 nm and 900 nm. 14. The system as claimed in claim 11, wherein the reaction chamber is a closed reaction chamber. 15. The system of claim 11, wherein the melanin is selected from natural melanin and synthetic melanin. 16. The system of claim 11, wherein the melanin is the only water-electrolyzable material present in the system.