KR101831946B1 - Method for Regenerati ing Cofactor Using Silicon Based Photoelectrode - Google Patents

Abstract

The present invention relates to a silicon-based photoelectrochemical cell containing a 3-jn-Si / ITO / CoPi photocathode and a silicon nanowire (H-SiNW) photocathode and a method for regenerating cofactors using the same. Based photovoltaic cells can be used as a platform to synthesize high value added compounds by using materials that are abundant in nature and sustainable energy sources.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method of regenerating coercive force using a silicon-

The present invention relates to a photoelectrochemical cell containing a silicon-based photoelectrode and, more particularly, to a silicon-based photoelectrochemical cell containing a 3-jn-Si / ITO / CoPi photocathode and a silicon nanowire (H- And a method for regenerating cofactors using the same.

Water is known to act as an electron donor in the natural photosynthesis reaction of plants, and solar energy is converted into chemical energy by the movement of mineral oil electrons between photosystem II and I. Much effort has been devoted to study the redox reaction of biocatalysts and the oxidation reaction of water in a homogeneous system mimicking such natural photosynthesis.

Redox enzymes can produce optically highly pure compounds because they have a high selectivity for chemical reaction functions, enantiomers and reaction sites. Due to the diversity and selectivity of these reactions, the redox enzyme can perform several types of industrially useful chemical reactions typified by fine chemical synthesis. However, the use of NADH (nicotinamide adenine dinucleotide), which is used as a cofactor in biocatalysis, has been limited due to commercialization due to high price.

Since auxiliary agents play an equivalent role in the reduction of biocatalysts in redox reactions, efficient supply of cofactors is known as a major barrier in the enzymatic industry of high value-added fine chemicals. In order to solve these problems, research and development have been actively carried out through regeneration of oxidative cofactors.

Electrochemical regeneration has thus been considered as an attractive alternative to the existing second enzyme / substrate regeneration method (Biocatal. Biotransform., 22:63, 2004). However, in the electrochemical regeneration method, the reduction of NAD (P) + to NAD (P) H was also disadvantageous in that the regeneration efficiency was lowered due to the slow electron transfer rate between the electrode and NAD (P) + even under the thermodynamically favorable voltage condition. To solve this problem, a method of transferring electrons between an electrode and NAD (P) + by using an even mediator has been developed (Chem., 53: 1979, 1981; Chim.Acta, 284: 385 , 1993, Chim. Acta, 360: 171, 1998). However, since the recovery of the oxidative cofactor occurs only in the immediate vicinity of the electrode surface, the yield of synthesis in the overall reactor is very low, and when the overvoltage is applied to the electrode, cofactor isomers which are unintentionally inactivated in the enzymatic reaction are mass- There is a problem that the reaction efficiency is reduced due to the formation of an unnecessary film on the surface.

On the other hand, the photochemical regeneration method of co-factor, which has recently been spotlighted, simulates the photosynthesis of the natural system and enables the reproduction of low cost and environmentally friendly photochemical co-factors using infinite solar energy without supplying external power (Chem. Res 42, 1890-1898, 2009; Chem. Res., 34, 40-48, 2001).

The CO2 immobilization reaction represented by artificial photosynthesis is a research based on photosynthetic reactions in which high energy organic matter is synthesized from water and carbon dioxide by using sunlight as an energy source in the natural world. Recently, an environmentally friendly future technology Which is attracting new attention. In order to develop successful artificial photosynthesis technology, it is very important to efficiently design the photoexcitation electron transfer process that takes place through a complex process in the cascade system in the natural world.

Accordingly, when developing an artificial photosynthesis system based on a photoelectrochemical cell in which a solar / electric energy conversion system and an electric / chemical energy conversion system are separated, an electron transfer side reaction such as a back electron transfer is minimized , It has been confirmed that the photoelectric material and the water decomposition catalyst are immobilized in the same way as the photoelectrode, and the energy transfer efficiency can be increased by increasing the electron transfer rate.

An object of the present invention is to provide a photoelectrochemical cell in which a solar / electric energy conversion system and an electric / chemical energy conversion system are separated.

Another object of the present invention is to provide a method for regenerating cofactors using the photoelectrochemical cell.

It is still another object of the present invention to provide a method for producing formic acid from carbon dioxide using the photoelectrochemical cell.

In order to achieve the above object, the present invention provides a 3-jn-Si photocathode in which a catalyst layer is coated on npp + 3-silicon (3-jn-Si) And a photo negative electrode composed of a silicon nanostructure surface-modified with hydrogen ions, wherein the photo-positive electrode and the photo negative electrode are immersed in an electrolyte solution separated from each other.

The present invention also provides a method for manufacturing a photovoltaic cell comprising the steps of immersing a photocathode composed of a silicon nanostructure surface-modified with hydrogen ions in a solution containing an oxidative co-factor and an electron transfer mediator, Wherein the coated 3-jn-Si photocathode is immersed in a solution containing water, which is an electron donor, and then irradiated with light.

(A) a photocathode composed of a silicon nanostructure surface-modified with a hydrogen ion is immersed in a solution containing an oxidative co-factor and an electron transfer mediator, and a npp + 3-silicon (3-jn-Si ), A step of immersing a 3-jn-Si photocathode having a catalyst layer coated thereon in a solution containing water as an electron donor, and irradiating light to regenerate the co-factor; And (b) preparing a useful substance by using the regenerated cofactor in an oxidative source enzyme reaction of a substrate.

The present invention also provides a photocathode composed of a silicon nanostructure surface-modified with a hydrogen ion is immersed in a solution containing NAD + and an electron transfer mediator, formate dehydrogenase, in which carbon dioxide is continuously supplied , a 3-jn-Si photocathode in which a catalyst layer is coated on npp + 3-type silicon (3-jn-Si) is immersed in a solution containing water as an electron donor, and the solution, in which the photocathode and the photocathode are immersed, And then connecting the mixture through a brassiere and irradiating light.

The silicon-based photoelectrochemical cell according to the present invention can be utilized as a platform for synthesizing high-value added compounds by using a substance that is abundant in a natural energy source and a sustainable energy source.

FIG. 1 is a schematic view illustrating a process of immobilizing carbon dioxide by a photo-induced biocatalytic reaction by a silicon-based cell according to the present invention.
Fig. 2 shows a voltammogram of 3-jn-Si / ITO / CoPi photocathode during light irradiation at different electrodeposition times.
FIG. 3 (A) shows an SEM image of the H-SiNW photocathode, (B) shows the voltammogram of H-SiNW with and without M and NAD + under dark conditions and (C) Si / ITO / CoPi photocathode produced by electrodeposition of CoPi on 3-jn-Si / ITO at 0.9 V for 30 minutes, and (D) shows the SEM image of the 3-jn- The scan rate is 50mV / s.
4A shows the structure of a silicon-based PEC battery system composed of a 3-jn-Si / ITO / CoPi photocathode and an H-SiNW photocathode, and B shows the photocurrent of a silicon-based PEC cell when different voltages are applied C shows the yield of NADH regenerated for 3 hours when different voltages were applied, and D was 6V for the separated PEC and Watt PEC cells under light and dark conditions. , The yield of NADH.
Figure 5 compares the yield of conversion of formic acid over 5 hours and the Faraday efficiency with sequential addition of each component of the reaction mixture in a PEC cell. The right-hand color shows the result when Pt electrode was used instead of 3-jn-Si / ITO / CoPi photocathode.
FIG. 6A is a schematic diagram of a solar-tracking module, B is a view of the solar-tracker moving according to the movement of the sun, C is a photocurrent amount according to the weather, D is CO ₂ Conversion of formic acid.

Among photochemical or photo-electrochemical carbon dioxide immobilization reactions based on existing artificial photosynthetic techniques, the photo-electrochemical carbon dioxide immobilization technique using semiconductors can use water as a source of electrons and hydrogen ions, but the selectivity for the carbon dioxide conversion reaction is inferior There is a problem that two or more substances are generated from carbon dioxide due to adverse reactions occurring in the electrodes, and there is a problem that a process of separating them is further required. In addition, conventional researches have focused on the use of high-priced semiconductors such as InP, GaP, GaAs, and CdTe as photoelectrode materials, which limits the application to industrialization.

On the other hand, carbon dioxide conversion using oxidoreductase has the advantage of high selectivity to convert carbon dioxide into a specific substance, but it is difficult to use a water degradation reaction as an electron source as well as a problem of using a coenzyme which is an expensive auxiliary agent.

The present inventors' previous studies have shown that a redox enzyme reaction system capable of efficiently utilizing a small amount of cofactors can be constructed by reducing the oxidized cofactors through a photochemical method and thus can be economically applied to the carbon dioxide conversion reaction .

Therefore, the present invention combines the advantages of a semiconductor-based reaction and a CO 2 immobilization system using an oxidizing enzyme reaction to continuously regenerate a small amount of a coenzyme, nicotinanimide cofactor (NADH) using electrons and hydrogen ions supplied from water through a photo- Thiobacillus sp. (TSFDH) redox enzyme reaction, thereby constructing an artificial photosynthetic-based photoelectrochemical carbon dioxide immobilization system capable of forming only a specific formate (Fig. 1).

Accordingly, in one aspect, the present invention provides a method for producing a 3-jn-Si photocathode having (a) a catalyst layer coated on npp + three kinds of silicon (3-jn-Si); And (b) a photonic cathode composed of a silicon nanostructure surface-modified with hydrogen ions, wherein the photon-emitting electrode and the photocathode are immersed in a separate electrolyte solution .

In the present invention, the electrolyte solutions separated from each other may be connected through a brassiere.

In the present invention, the catalyst layer may be cobalt phosphate (CoPi), and the npp + 3-type silicon (3-jn-Si) may be coated with indium tin oxide (ITO).

Preferably, the photocathode of the present invention is formed of 3-jn-Si / ITO coated with cobalt phosphate (CoPi) on indium tin oxide (ITO) coated on npp + 3 type silicon (3-jn-Si) -Jn-Si / ITO / CoPi photocathode, and the photocathode is a photocathode composed of a silicon nanowire (H-SiNW) surface-modified with hydrogen ions.

FIG. 1 shows a process of immobilizing carbon dioxide by a photo-induced biocatalytic reaction with a silicon-based cell according to the present invention. 3-jn-Si / ITO / CoPi Electrons generated by the oxidation of water at the Kwangyang electrode are transferred to the H-SiNW photocathode. The electrons are excited by visible light irradiation, transferred to NAD + via M (rhodium-based electron transfer mediator), and the reduced NAD + (ie NADH) forms two electrons and one electron through FDH catalysis to form carbon dioxide To the reaction that converts it to.

Silicon is an ideal energy-harvesting material for developing efficient artificial photosynthesis systems in that it can absorb a broad spectrum of sunlight, including visible light, along with long-term economic viability. In the present invention, a carbon dioxide immobilization system using a photo-electrode composed of a silicon-based material is designed.

In the present invention, np ⁺ triplet junction silicon is used as a light-emitting electrode material by using a material (3-jn-Si / ITO / CoPi) in which ITO and a water decomposition catalyst are coated on (3-jn- The holes excited by light are rapidly transferred to the water decomposition promoter as compared with silicon so as to enhance the water decomposition efficiency. On top of the npp ⁺ triplet junction silicon, cobalt phosphate (CoPi), a well known and efficient water decomposition promoter, was coated to maximize the supply of electrons from water.

As a photocathode material used in the present invention, a silicon nanowire (H-SiNW) having hydrogen atoms treated with photochemical NADH regeneration has been selected. H-SiNW is known to have higher solar energy conversion efficiency than bulk silicon due to its quantum confinement effect. In photocatalytic systems, Rh-based organometallic electron mediators { M; [Cp * Rh (bpy) ( H 2 O)] 2+, Cp * = C 5 Me 5, is effective to deliver a hydride to bpy = 2,2'-bipyridine}.

M (ie, Mox) receives two electrons from H-SiNW, accepts both in solution and is reduced to M _red , and returns to the previous oxidation state while providing hydride to NAD +.

 In addition, H-SiNW has a large surface area where catalytic reaction can occur compared to planar silicon. One-dimensional structure of nanowire enables effective separation of electrons and holes formed by sunlight to increase efficiency of carbon dioxide conversion reaction It will be possible.

In another aspect of the present invention, there is provided a method of manufacturing a semiconductor device comprising the steps of: immersing a photocathode composed of a silicon nanostructure surface-modified with hydrogen ions in a solution containing an oxidizing co-factor and an electron transfer agent; Characterized in that a 3-jn-Si photocathode having a catalyst layer coated thereon is immersed in a solution containing water as an electron donor and then irradiated with light.

In the present invention, the oxidizing auxiliary may be selected from the group consisting of NAD ⁺ (nicotinamide adenine dinucleotide), NADP ⁺ (nicotinamide adenine dinucleotide phosphate), flavin adenine dinucleotide (FAD ⁺ ), FMN ⁺ (flavin monocleotide) And lipoic acid. In the present invention, the electron transport mediator may be selected from the group consisting of methyl viologen, ruthenium II complex and rhodium III complex.

In the present invention, the catalyst layer may be cobalt phosphate (CoPi), and the npp + 3-silicon-3-jn-Si may be coated with indium tin oxide (ITO) The photocathode may be a photocathode formed of silicon nanowires (H-SiNW) whose surface is modified with hydrogen ions.

And the solution in which the photocathode and the photocathode are immersed is connected through a brassiere.

In one embodiment of the present invention, a cell connected between a 3-jn-Si / ITO / CoPi light-emitting electrode and an H-SiNW light-emitting electrode is connected to the TsFDH reaction, thereby being supplied by water decomposition at 3-jn-Si / ITO / CoPi In order to confirm that electrons are effectively transferred to H-SiNW and that the electrons are transferred to TsFDH through NADH regeneration, CO ₂ can be effectively transferred to formate. First, in order to confirm that the silicon- The conditions under which NADH regeneration is efficiently performed, which is an essential condition for the immobilization of CO ₂ by TsFDH combined with the cell, is confirmed.

As a result, it was confirmed that the voltage at which sufficient photocurrent can flow through the photocathode for NADH regeneration should be 0.4 V or more. As a result, the efficiency of NADH regeneration was measured by external human voltage. As a result, it was observed that the regeneration efficiency was lowered at an applied voltage of 0.8 V although the efficiency was increased up to 0.7 V. This is because if the photocurrent flowing to the photo- -SiNW (Fig. 4). ≪ tb > < TABLE >

Based on the above results, experiments were carried out under an applied voltage of 0.6 V in consideration of efficient external energy input and efficient regeneration efficiency in an experiment to be carried out for immobilization of CO ₂ based on a photoelectrode cell. Further, it was confirmed that each of the photoelectrodes was immersed in a different reaction mixture, and that NADH could be efficiently regenerated only under the light irradiation condition. Thus, the photoelectrode cell is capable of regenerating electrons supplied by water decomposition, It is possible to transfer NADH to the regeneration reaction while minimizing migration.

In a one-pot system in which a photocathode and a photocathode are immersed in the same solution, it is very difficult to couple the photocatalyst and the biocatalyst using water as an electron donor. Thus, the rear electron transfer can be reduced by a PEC platform that physically separates water degradation and cofactor (NAD +, etc.) reduction. For example, in a separate PEC cell structure, the regeneration rate of NADH was 23.1%, but the recycling rate of NADH in the one-pot system was only 2.2%.

(A) immersing a photocathode composed of a silicon nanostructure surface-modified with a hydrogen ion in a solution containing an oxidizing cofactor and an electron transfer mediator to form an npp + triple silicon (3- jn-Si) coated with a catalyst layer is immersed in a solution containing water, which is an electron donor, and then light is irradiated to regenerate the co-factor; And

(b) preparing a useful substance by using the regenerated cofactor in an oxidative source enzyme reaction of a substrate.

In the present invention, the useful substance produced by the regenerated cofactor is selected from the group consisting of glutamate, aspartate, lactate, unnatural aminoacid, Ibuprofen, pravastatin, And is selected from the group comprising Texol, optical isomers and artificial amino acids.

According to another aspect of the present invention, there is provided a method for producing a photoacid generator comprising a photocathode composed of a silicon nanostructure surface-modified with a hydrogen ion, wherein the photocathode comprises NAD + and an electron transfer mediator and a formate dehydrogenase, Immersing the 3-jn-Si photocathode in which a catalyst layer is coated on pp + 3-type silicon (3-jn-Si) in a solution containing water serving as an electron donor and then immersing the photocathode and the photocathode in a solution And the resulting solution is connected via a bridge and irradiated with light.

In the present invention, the catalyst layer may be cobalt phosphate (CoPi), and the npp + 3-silicon-3-jn-Si may be coated with indium tin oxide (ITO) The photocathode may be a photocathode formed of silicon nanowires (H-SiNW) whose surface is modified with hydrogen ions.

In one embodiment of the present invention, formate dehydrogenase (FDH) used for the biocatalytic reaction of formic acid is an oxidoreductase which simultaneously activates formate oxidation and carbon dioxide reduction. There are several types of NADH-dependent FDHs, including CbFDH, CsFDH, AaFDH, PsFDH, and TsFDH, which are easily available for commercial use depending on their expression types. In general, FDH indicates that the preference for formate oxidation is related to the carbon dioxide reduction reaction It is difficult to realize the carbon dioxide immobilization reaction by FDH. However, according to recent studies, Thiobacillus sp. (TsfDH) has been reported to be superior to other FDHs in catalytic activity for the carbon dioxide reduction reaction (H, Choe et al., Plosone, 9: e103111, 2014). Therefore, in one embodiment of the present invention, the CO ₂ immobilization reaction is performed using TsFDH as a biocatalyst.

In another embodiment of the present invention, a solar-tracker is used to determine whether solar-based photovoltaic cells can be used as a sustainable energy harvesting system. As a result, it is confirmed that formic acid is generated by carbon dioxide immobilization It was also confirmed that the yield of formic acid produced according to the change of sunlight changes. This connection has proved that it can be used as a platform to synthesize high value-added precise compounds by using sustainable energy sources such as sunlight and substances (carbon dioxide, water) abundant in the natural world.

Hereinafter, the present invention will be described in more detail with reference to Examples. It is to be understood by those skilled in the art that these examples are for illustrative purposes only and that the scope of the present invention is not construed as being limited by these examples.

Example 1: Fabrication of silicon-based photoelectrodes

1-1: Production of 3-jn-Si / ITO / CoPi photovoltaics

The 3-jn-Si / ITO / CoPi photocathode was fabricated by electrodeposition of CoPi on 3-jn-Si / ITO. Synthesis of 3-jn-Si / ITO (0.8 x 2 cm ² ) was carried out in a 3-electrode voltage electrode structure (3-jn-Si / ITO working electrode, Ag / AgCl reference electrode and Pt line counter electrode) mM Co (NO ₃ ) ₂ 6H ₂ O in a solution of 100 mM KPi buffer (pH 7). Thereafter, an external voltage of 0.9 V was applied for different time to electrodeposit CoPi on the 3-jn-Si / ITO surface, and CoPi was electrodeposited on the ITO side. The deposition time was 5 minutes, 10 minutes, 30 minutes and increasing to 60 minutes, CoPi amount of charge each 3.1 mC / cm ^2, to pass during electrodeposition ^{5.6 mC / cm 2, 14.0 mC} / cm 2 and 31.4 mC / cm ² , respectively. As the electrodeposition time increased to 5, 10, 30 and 60 minutes, the onset potential for water degradation shifted to negative polarity. However, an increase in the initiation potential was observed at an electrodeposition time of 60 minutes, which limited the hole transprot of the thick CoPi film to reduce the catalytic effect on water molecules (FIG. 2). Therefore, in the following examples, electrodeposited samples were used for 30 minutes.

FIG. 3C shows an SEM image of a 3-jn-Si / ITO / CoPi photocathode prepared by electrodepositing CiPi to 3-jn-Si / ITO at 0.9 V for 30 minutes, And the volta - nograms with and without CoPi catalysts are shown.

1-2: Fabrication of H-SiNW photocathode

H-SiNW photocathodes were synthesized by metal-assisted solution etching. Specifically, p-type silicon wafers (1 x 7 cm ² ) were washed with acetone, ethanol, 2-propanol and piranha solution for 5 minutes, washed several times with deionized water, immersed in 5% HF solution for 3 minutes, , Immersed in a solution of 5 mM AgNO ₃ and 4.8 M HF for 1 minute, and rinsed thoroughly with deionized water. The wafer was allowed to stand for 30 minutes in a 0.4M H ₂ O ₂ and 4.8M HF solution under dark conditions. After washing several times with deionized water, the silver nanoparticles remaining in the HNO ₃ : water (5: 5) solution for 1 hour were removed. Thereafter, the wafer was cut into 1 x 1 cm < ² > and connected to a copper wire using carbon paste covered with an epoxy resin to make an electrode. The H-SiNW photocathode was treated with 5% HF solution for 5 minutes before use to modify the surface with hydrogen.

Example 2: Photochemical NADH regeneration

In order to perform Gwangyang pole induction NADH optical reproducing, H-SiNW photocathodes (1 x 1cm ²⁾ On the (450 W Xe lamp with a 420 nm cut-off filter) condition irradiation, containing 1 mM NAD ^+, and 250μM M Dipped in 100 mM phosphate buffer (pH 7, 10 ml) (Fig. 4A).

 As a result of the cyclic voltammogram, the maximum increase in the reduction current was a solution containing 250 μM of M, and no further increase in the solution containing 500 μM of M was confirmed. Therefore, 250 μM of M was used in the following examples. The oxidation of water to provide electrons to the H-SiNW photocathode was performed by irradiating light with a 450 W Xe lamp with a 420 nm cutoff filter in a 50 mM phosphate buffer solution (pH 7, 15 ml).

The NADH photoresponsive solution was connected to the water decomposition solution through a salt bridge in a 3-electrode voltage electrode structure (3-jn-Si / ITO working electrode, Ag / AgCl reference electrode and H- SiNW counter electrode) V (vs Ag / AgCl). During the reaction, the regenerated NAD + concentration was measured at 340 nm using a V-650 spectrophotometer (JASCO Inc., Japan). For one-pot NADH light regeneration, the photoperiod and photocathode were immersed in the same reaction solution (1 mM NAD + and 250 μM Rh-based electron mediator, pH 7 phosphate buffer (100 mM)). The NADH regeneration test was conducted for 3 hours until the amount of NADH produced was saturated. The water decomposition and NADH regeneration process was performed by irradiating the photocathode and photocathode with visible light (λ> 420 nm) at pH 7 Respectively.

As a result, as shown in FIG. 4, 3-jn-Si / ITO / CoPi and H-SiNW photoelectrodes were connected through a 3-elctrode configuration and the photocurrent was measured according to the external applied voltage. It was confirmed that the voltage at which sufficient orphan current can flow is 0.4 (vs. Ag / AgCl) (FIG. 4B). As a result, the efficiency of the NADH regeneration efficiency was measured according to the externally applied voltage. As a result, the efficiency was increased up to 0.7 V, but the regeneration efficiency was lowered under the application of 0.8 V (FIG. 4C) And the possibility of participating in the side reactions occurring in the H-SiNW on the ground becomes greater.

Based on the above results, experiments were carried out under an applied voltage of 0.6 V in consideration of efficient external regeneration efficiency and minimum external energy input in an experiment to be carried out for CO2 fixing based on a photo electrode cell. In addition, it was confirmed that each of the photoelectrodes was located in different reaction mixture and NADH could be efficiently regenerated only under the light irradiation condition (Fig. 4D). Thus, It is possible to minimize the back electron transfer and transfer it to the NADH regeneration reaction.

Example 3: Production of CO ₂ Reduction to formic acid

CO ₂ -immobilization with GFDH (SEQ ID NO: 1) was carried out by continuous CO ₂ bubbling for 5 hours in 100 mM phosphate buffer (pH 7, 15 ml) containing 1 mM NAD +, 250 μM Rh-based electron mediator and TsFDH 3 mg (bubbling) conditions.

In TsFDH, CO ₂ is captured at Lys 287 and transported to the active site of the NADH-binding TsFDH, CO ₂ is stabilized at Arg285, and TsFDH releases NAD + and formate. Prior to the addition of each reaction component, 100 mM phosphoric acid solution was saturated with CO ₂ gas, and the temperature of each reaction mixture was kept at about 32 ° C by irradiation effect. The other experimental conditions were the same as those of Gwangyang - gu induced NADH light regeneration. The formic acid concentration was determined by diluting the solution with H ₂ SO ₄ to inactivate TsFDH and calculating the area of the formic acid peak,  (LC-20A, Shimadzu, Japan) equipped with an HPX-87H ion exclusion column.

In order to confirm the contribution of each photoelectrode, CO ₂ fixation was performed using the same full-cell except for using 3-jn-Si / ITO / CoPi working electrode and Pt or Pt working electrode and H- System.

The faradaic efficiency for formic acid was calculated by the following formula:

Faradaic efficiency =

Where n is the number of electrons required for formic acid production, F is the Faraday constant and Q is the charge flowing during the reaction.

For the successful formation of formate, the electrons transferred from the 3-jn-Si / ITO / CoPi photocathode are transported through the H-SiNW to Rh - mediator, NAD +, and TsFDH.

Thus, the components were added one by one to the reaction mixture for the synthesis of formic acid, and the amount of the formic acid synthesized was then compared to confirm that the electrons were continuously transferred to the respective components.

As a result, as shown in FIG. 5, when the Rh-mediator and NAD + were sequentially added, the amount of formic acid produced on the surface of H-SiNW was reduced as compared with the case where only H-SiNW was present. However, in the reaction with TsFDH added, a total of 1.06 mM formic acid was produced for 5 hours, which corresponds to 4.6 times the amount of formic acid (0.23 mM) produced when only H-SiNW was present. It was confirmed that the photo-induced electrons generated in the H-SiNW were efficiently transferred to the NAD + via the Rh-mediator and efficiently participated in the TsFDH reaction. In addition, the faraday efficiency (21.6%) for the formation reaction of TsFDH by the H-SiNW alone was considerably higher than the faraday efficiency (7.5%) for the formic acid generation reaction occurring on the electrode surface when H-SiNW alone existed. It was found that the catalytic reaction system also increased the selectivity for the carbon dioxide immobilization reaction.

In addition, the effect of 3-jn-Si / ITO / CoPi and H-SiNW photoelectrodes was confirmed by investigating how each photoelectrode was substituted with a Pt electrode. As shown in FIG. 5, when the H-SiNW phonetic electrode was replaced with a Pt electrode, the amount of formic acid was reduced to 0.1 mM and the faraday efficiency for this reaction was only 0.22%. This shows that the additional redox potential of H-SiNW in the light irradiation condition plays a crucial role in transferring electrons to the Rh mediator. In addition, when the 3-jn-Si / ITO / CoPi photocathode electrode was replaced with a Pt electrode, the amount of formic acid was reduced to 0.06 mM and the Faraday efficiency for this reaction was found to be only 1.91% It has been confirmed that the supply of electrons by water decomposition reaction in -Si / ITO / CoPi is an important driving force for driving the carbon dioxide immobilization system.

Example 4: Application of silicon-based photoelectrochemical cell to solar-trackerd

In order to apply the silicon-based photovoltaic cell of Example 3 to a sustainable energy harvesting system, solar-tracker was used to confirm whether actual solar light could be used.

In this embodiment, it was confirmed that the CO2 fixation by TsFDH was also performed under actual solar irradiation, and the solar panel in the sola-tracker was able to receive the maximum sunlight while changing its angle according to the movement of the sun 6). The sunlight irradiated on the solar panel is transmitted to the optoelectrochemical cell in the laboratory through the optical fiber.

As shown in FIG. 6, the intensity of natural light according to the weather had a direct effect on the photocurrent density flowing in the battery, and it was confirmed that it led to the change of the formic acid production rate by TsFDH Respectively. Based on these results, it has been confirmed that the silicon-based photoelectrochemical cell according to the present invention can be utilized as a platform for synthesizing high-value-added precision compounds by using a substance that is abundant in a natural energy source and a sustainable energy source .

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. something to do. It is therefore intended that the scope of the invention be defined by the claims appended hereto and their equivalents.

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Claims (18)

(a) 3-jn-Si / ITO / CoPi photocathode in which indium tin oxide (ITO) and cobalt phosphate (CoPi) layers are coated on npp + 3-silicon (3-jn-Si); And
(b) a photonic cathode composed of silicon nanowires (H-SiNW) surface-modified with hydrogen ions,
Wherein the photocathode and the photocathode are immersed in an electrolyte solution separated from each other and connected to each other through a brassiere where electrons move.
delete delete delete delete A photocathode composed of a silicon nanowire (H-SiNW) surface-modified with a hydrogen ion is immersed in a solution containing an oxidizing co-factor and an electron transfer mediator,
A 3-jn-Si / ITO / CoPi photovoltaic cell in which indium tin oxide (ITO) and cobalt phosphate (CoPi) layers are coated on npp + ternary silicon (3-jn-Si) After immersion,
The photocathode immersed in the electrolyte solution is connected to the photocathode through a bridle through which electrons move,
And irradiating the light with a light.
7. The method of claim 6, who the oxidized cofactor NAD ⁺ (nicotinamide adenine dinucleotide), NADP ⁺ (nicotinamide adenine dinucleotide phosphate), flavin cofactor design FAD ⁺ (flavin adenine dinucleotide), FMN ⁺ (flavin monoucleotide), intracellular hemin &Lt; / RTI &gt; and lipoic acid.
7. The method of claim 6, wherein the electron transfer mediator is selected from the group consisting of methyl viologen, ruthenium II complex and rhodium III complex.
delete delete delete delete An artificial photosynthetic method, characterized in that a co-factor regenerated by claim 6 is used in an oxidative source enzyme reaction of a substrate to produce a useful substance.
14. The method of claim 13, wherein the useful substance produced by the regenerated cofactor is selected from the group consisting of glutamate, aspartate, lactate, unnatural aminoacid, Ibuprofen, pravastatin, , Texol, optical isomers and artificial amino acids. &Lt; RTI ID = 0.0 &gt; 8. &lt; / RTI &gt;
A photocathode composed of silicon nanowires (H-SiNW) surface-modified with hydrogen ions is immersed in a solution containing NAD + and an electron transfer mediator, formate dehydrogenase, in which carbon dioxide is continuously supplied ,
A 3-jn-Si / ITO / CoPi photovoltaic cell in which indium tin oxide (ITO) and cobalt phosphate (CoPi) layers are coated on npp + ternary silicon (3-jn-Si) The solution immersed in the photocathode and the photocathode is connected through a bridle to which electrons are transferred,
Wherein the step of irradiating light with a light is carried out. delete delete delete

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