A METHOD OF SOLVENT-FREE SULFUR-BRIDGE-EOSIN-Y (SBE-Y) POLYMERIC FRAMEWORK PHOTOCATALYST

Abstract

This invention introduces A solvent-free sulfur-bridge-eosin-Y (SBE-Y) polymeric framework photocatalyst was prepared for the first time through an in situ thermal polymerization route using elemental sulfur (S8) as a bridge. The addition of a sulfur bridge to the polymeric framework structure resulted in an allowance of the harvesting range of eosin-Y (E-Y) for solar light. This shows that a wider range of solar light can be used by the bridge material's photocatalytic reactions. In this context, supercharged solar spectrum: enhancing light absorption and hole oxidation with sulfur bridges. This suggests that the excited electrons and holes through solar light can contribute to oxidation-reduction reactions more potently. As a result, the photocatalyst-enzyme attached artificial photosynthesis system developed using SBE-Y as a photocatalyst performs exceptionally well, resulting in high 1,4- NADH regeneration (86.81%), followed by its utilization in the exclusive production of formic acid (210.01 µmol) from CO2 and synthesis of fine chemicals with 99.9% conversion yields. The creation of more effective photocatalytic materials for environmental clean-up and other applications that depend on the solar light-driven absorption spectrum of inorganic and organic molecules could be one of the practical ramifications of this research.

Specification

DESC:FIELD OF THE INVENTION
The present invention relates to a method of solvent-free sulfur-bridge-eosin-Y (SBE-Y) polymeric framework photocatalyst.
BACKGROUND OF THE INVENTION
References which are cited in the present disclosure are not necessarily prior art and therefore their citation does not constitute an admission that such references are prior art in any jurisdiction. All publications, patents and patent applications herein are incorporated by reference to the same extent as if each individual or patent application was specifically and individually indicated to be incorporated by reference.
The use of renewable solar energy to clear up major environmental contamination is an important problem. The development of innovative photocatalytic materials is a critical step towards resolving this intractable challenge. Under solar light, various light-harvesting semiconductor materials, such as metal-organic framework, Se and S-doped graphitic carbon nitride, metal based inorganic nanocrystals (1-3), and polymeric materials, were discovered to efficiently break down organic pollutants, reduce the CO2 into solar fine chemicals, and produce green energy sources from water.(4-7)(8-10) These materials have garnered interest due to their unique chemical stability, decreased production costs, and enhanced capacity to use solar energy. These materials are metal-free photocatalysts. Then, to improve the photocatalytic ability of these materials, much effort was put into increasing the harvesting of these synthetic materials for solar light and altering the band structure properties. Metal-organic framework (MOF), NP/ZIS-heterostructures, chalcogenides, (11, 12) and chemically doping graphitic carbon nitride (g-C3N4) with expensive and nonmetal elements like Pt, Zr, Re, Ru, Ni, Cu, and F, P, or chalcogen family have so far been found to be a successful method for enhancing its photocatalytic ability. (13-16) The most elusive of them is the element Zr, Re, selenium (Se), and sulfur (S), whose modification of the electronic band structure and optical absorption property of MOF and g-C3N4 depends greatly on the kind of precursor Re, Se, and S and the synthetic processes used to produce it. After post-processing of MOF PCN-224, and g-C3N4 in a suitable environment to add expensive Zr metal and low-cost sulfur metal, it was discovered that PCN-224 and g-C3N4's valence band (V.B.) and conduction band (C.B.) minimum (C.B) broadened as a result of the one phase substitution of zirconium and sulfur for lattice nitrogen. By using MoSe2, and MoSe2 as a hard template and in situ polymerizing selenourea, and thiourea, a selenium, and sulfur atom was doped in the carbon position of a mesoporous g-C3N4 i.e.; Se- g-C3N4 and S- g-C3N4, which caused downshifts in its LUMO and HOMO. (16) A novel conjugated polymer with a disulfide (-S-S-) bond is created by several researchers using sulfur-containing trithiocyanuric acid (TTCA) organic forerunners. The disulfide bond is thought to be crucial to the development of conjugated polymers that have the ability to absorb light and transport electrons.(17) They also achieve that the insertion of a sulfur atom into g-C3N4 could minimize the level of energy of the V.B, and enhance the evolution of oxygen, CO2 fixation, and organic transformation activity of the g-C3N4-based polymer semiconductor even when the existence of sulfur in minor majority persisted in the evaluating sample.(18) However, the negligence of S moieties in the prepared g-C3N4 photocatalysts was exposed when a straightforward sulfur-containing molecule, such as ammonium thiocyanate, trithiocyanuric acid, and S8, is used as the precursor in the synthesis of sulfur-based materials for various applications.(19-21)
According to these findings, sulfur doping's underlying mechanism for altering the electronic properties of band structure as well as optical characteristics of diverse semiconductor light-harvesting material is significant and merits further study. Previously, we have created a donor-acceptor light-harvesting material by consistently integrating electron-deficient cyanuric chloride (CC) blocks into the precursors of perylene-tetracarboxylic-diimide (PDI) through direct condensation of CC and PDI at a 90 °C.(22) The electronic charge distribution on this reported photocatalyst(22) is "located" on the CC block as opposed to the uniform distribution on the 2D CTF due to the effect of electron-deficient CC, suggesting that a non-uniform dissemination of electronic charge may provide the dopant with easy access.
In this article, we first present a superb light-harvesting sulfur-bridging eosin-Y (SBE-Y) photocatalyst that was created by in situ thermal polymerization of a single monomer of eosin-Y (E-Y) and S8 at 160 ? for two hours. The produced catalysts were thoroughly examined using tools such as UV-visible & FTIR spectroscopy, SEM along with elemental analysis, TEM, XRD, BET, HR-TEM, XPS, and CV to determine where the sulfur is located in the SBE-Y framework and how sulfur doping affects the material's optical characteristics and electronic band structure. Under solar light illumination, the activity of SBE-Y photocatalyst was evaluated for CO2 fixation and fine chemical synthesis. Additionally, SBE-Y is presumably a specific photocatalyst material designed for this purpose. It likely has unique properties that make it effective at harnessing solar energy to drive the CO2 transformation process efficiently. The CO2 transformation refers to the conversion of CO2 into other compounds, such as solar chemicals, using various chemical reactions. This is often done to mitigate CO2 emissions and produce valuable formic acid products simultaneously. The C-N bond activation is a specific type of chemical reaction that involves breaking and forming bonds between carbon (C) and nitrogen (N) atoms. This step is essential in many chemical transformations, including the synthesis of valuable compounds from CO2. Solar fuel production is an area of research that aims to use renewable energy sources, such as sunlight, to produce fuels or chemicals from abundant and sustainable feedstocks like CO2. This approach can help address both energy and environmental challenges.
Several patents issued for photocatalysts but none of these are related to the present invention. Patent CN106076366B discloses a kind of short-bore road ordered mesopore carbon sulfur loaded indium cobalt and sulphur indium nickel Three-element composite photocatalyst and its preparation method and application. Short-bore road ordered mesopore carbon sulfur loaded indium cobalt and sulphur the indium nickel Three-element composite photocatalyst is to mix pretreated short-bore road mesoporous carbon with cobalt salt, nickel salt, indium salts and reducing agent, is made through hydro-thermal reaction. Short-bore road ordered mesopore carbon is that short-bore road ordered meso-porous silicon oxide and carbon source are calcined acquisition under nitrogen protection, and short-bore road ordered meso-porous silicon oxide is to be obtained by the mixture of surfactant, hydrochloric acid solution, ammonium fluoride and ethyl orthosilicate after the calcining of collosol and gel hydro-thermal is reacted successively. The photochemical catalyst has stronger adsorptivity and visible light catalysis activity to VOCs, just effectively can adsorb and degrade in catalyst surface original position be enriched with VOCs, the reaction rate and efficiency of photocatalysis degradation organic contaminant are greatly enhanced, adsorbent or photocatalyst applications can be used as in field of environment protection.
Another patent US11628432B2 discloses a nitrogen-doped mesoporous carbon-coated Titanium dioxide composite photocatalyst, a preparation method and use thereof. The preparation method comprises the steps of: dissolving an organic ligand and Ti(OC3H7)4 in a mixture of methanol and DMF at a certain ratio, performing a hydrothermal reaction, centrifuging and drying to obtain a Titanium-based metal organic framework (Ti-MOF); pyrolyzing the obtained Ti-MOF under an inert atmosphere, and oxidizing the same for etching to obtain a nitrogen-doped mesoporous carbon-coated Titanium dioxide composite photocatalyst. The obtained composite photocatalyst not only facilitates the adsorption, enrichment and mass transfer of low concentration VOCs, but also efficiently degrades VOCs under sunlight. It has high degradation activity and stability when performing photocatalytic removal of VOCs in the presence of visible light, is simple in synthesis, low in preparation cost, and has strong potential for the use in environmental protection.
Another patent CN110152711B belongs to the field of nano material preparation and discloses CeO2@MoS2/g C3N4The composite photocatalytic material is prepared through (1) adding cerium oxide hexahydrate into the mixed solution of butylamine and toluene, hydrothermal treatment of the mixed solution, and calcining the reaction product to obtain CeO2A nanocrystal; (2) mixing sodium molybdate dihydrate with g-C3N4The nano-sheets are ultrasonically dispersed in a mixed solution of L-cysteine and dimethyl sulfoxide, and the obtained mixed solution is subjected to hydrothermal treatment to obtain MoS2/g C3N4Nanosheets; (3) adding CeO2Nanocrystalline and MoS2/g C3N4Ultrasonically dispersing in methanol solution, volatilizing methanol, and collecting the obtained product as CeO2 MoS2/g C3N4A composite material; (4) adding CeO2 MoS2/g C3N4The composite material is placed in a tube furnace and calcined in the nitrogen atmosphere to obtain CeO2@MoS2/g C3N4A ternary composite photocatalyst. The preparation method is simple and has strong controllability, and the obtained composite photocatalyst has excellent photocatalytic degradation performance.
Another patent US10105687B1 photocatalyst in the form of chloroplast-like heterostructures of Bi2S3-ZnS is disclosed. Additionally, methods for producing the chloroplast-like heterostructures of Bi2S3-ZnS with controlled morphology, as well as methods for the photocatalytic production of hydrogen gas under visible light irradiation employing the chloroplast-like heterostructures of Bi2S3-ZnS are disclosed.
Another patent US20220395821A1 describes a covalent organic frameworks. The covalent organic frameworks have unique structural and physical properties, which lends them to be versatile in a number of different applications and uses. In one aspect, the covalent organic frameworks are composed of a plurality of fused aromatic groups and electron-deficient chromophores. The covalent organic frameworks are useful as photocatalysts in a number of different applications.
OBJECTS OF THE INVENTION
Main object of the present invention is a Solar -Light Efficient C(sp3)-N Bond Activation and CO2 Transformation via Newly Designed SBE-Y Cutting-Edge Dynamic Photocatalyst
Another object of the present invention is to provide a novel sulfur-bridge eosin-Y (SBE-Y) polymeric photocatalyst synthesized through a solvent-free thermal polymerization method using elemental sulfur (S8) as a bridging agent.
Another object of the present invention is to expand the solar light absorption range of eosin-Y by integrating a sulfur bridge, thereby enhancing the photocatalytic efficiency of the material.
Another object of the present invention is to facilitate effective oxidation-reduction reactions by creating excited electron and hole pairs through enhanced light harvesting, enabled by the sulfur bridge.
Another object of the present invention is to achieve high-performance artificial photosynthesis for environmental applications, including significant 1,4-NADH regeneration and selective CO2 conversion to formic acid, using SBE-Y in photocatalyst-enzyme systems.
Another object of the present invention is to provide a scalable and cost-effective approach to producing photocatalytic materials for solar-driven applications, supporting environmental cleanup, renewable energy generation, and fine chemical synthesis.
SUMMARY OF THE INVENTION
Using the procedure developed by Kolle and Grtzel, the hydridorhodium complex, RhCl, was created. Hexamethyldewarbenznene (HMDB), 100 mg, and RhCl3.3H2O, 500 mg, were combined in 15 mL of MeOH and agitated at 65 ? under N2 for 15 hours. After the mixture had reached ambient temperature, the solvent was drawn off under vacuum. To take out excess hexamethylbenzene, the residue was purified by ether. These left oily red viscous materials, which were then extracted with CHCl3. The mixture was evaporated under reduced pressure, dried in presence of MgSO4, and the residue was then recrystallized from CHCl3/benzene. When 2, 2'-bipyridine (2 eq.) was added, the suspension quickly cleared and a yellowish solution was produced.
Herein enclosed a sulfur-bridge eosin-Y (SBE-Y) photocatalyst synthesized via an in situ thermal polymerization process comprising of elemental sulfur (S8), eosin-Y, Hexamethyldewarbenznene (HMDB), 100 mg, and RhCl3.3H2O, 500 mg;
characterized by enhanced solar light absorption and efficient photocatalytic properties for CO2 transformation and C(sp³)-N bond activation.
A method for synthesizing the SBE-Y photocatalyst as claimed in claim 1, wherein the said method comprising the steps of:
Combining Hexamethyldewarbenznene (HMDB, 100 mg), and RhCl3.3H2O (500 mg) in 15 mL of MeOH and agitated at 65 ? under N2 for 15 hours;
Drawing off the solvent under vacuum after the mixture had reached ambient temperature;
Purifying the residue by ether to take out excess hexamethylbenzene;
Extracting these left oily red viscous materials with CHCl3;
Evaporating the mixtureunder reduced pressure, dried in presence of MgSO4, and the residue was then recrystallized from CHCl3/benzene;
Adding 2, 2'-bipyridine (2 eq.), and the suspension quickly cleared and a yellowish solution was produced;
Grinding (1.5 g) elemental sulfur powder and (500 mg) eosin- Y by utilizing a mortar and pestle for 20 minutes;
Keeping the mixture in the covered crucible and heated in a muffle furnace at 160 ºC for 2 hours; and
obtaining the 1.09 g light orange product as final product photocatalyst.
To regenerate NADH by photocatalysis, the QR was utilized to carry out the fixation of NAD+.
To regenerate NADH by photocatalysis, the NAD+ (0.62 mmol), Rh (0.31 mmol), photocatalyst (4 mg), and AsA (1.24 mmol) were the components of the reaction, which took place in 3.1 ml of NPB (100 mM).
The photocatalyst-enzyme system achieves a high conversion rate of CO2 to formic acid and demonstrates 1,4-NADH regeneration with efficiency greater than 86%.
The SBE-Y photocatalyst produced is employed in fine chemical synthesis applications, achieving conversion yields up to 99.9% under solar illumination.
The [Cp*Rh(bpy)Cl]Cl complex is used as a co-catalyst in the SBE-Y photocatalytic system to enhance the efficiency of CO2 conversion and C(sp³)-N bond activation reactions under solar light.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1. Synthesis pathway for electron mediator organometallic complex [Cp*Rh(bpy)Cl] Cl.
Figure 2. Powered XRD pattern of eosin-Y (E-Y, red) and sulphur-bridge- eosin-Y (SBE-Y, blue) framework photocatalyst.
Figure 3. (a) The UV-Visible absorption spectra of SBE-Y framework film photocatalyst with Tau plot for calculation of optical energy band gap (2.22 eV) and (b) FTIR spectra of S8 (Blue), E-Y (grey) monomers and SBE-Y (red) framework photocatalyst.
Figure 4. a) 3D structure of the SBE-Y photocatalyst (b) TEM image of SBE-Y and (c) SEM image of SBE-Y along with elemental mapping images of (d) C, (e) O, and (f) S.
Figure 5. Photocatalytic activity E-Y, and SBE-Y photocatalysts for (a) selective photoregeneration of cofactor 1,4-NADH [NAD+ (0.62 mmol), Rh (0.31mmol), photocatalyst (4 mg), and AsA (1.24 mmol) in 3.1 mL of neutral phosphate buffer (NPB~100 mM)], and (b) AsA (1.24 mmol), NAD+ (0.62 mmol), photocatalyst (4 mg), Rh complex (0.31 mmol), and formate dehydrogenase (FateDH~3 units) in 3.1 mL of above-mentioned phosphate buffer are used in the selective enzymatic synthesis of formic acid (HCOOH) from CO2 under solar light.
Figure 6. Cyclic voltammograms of (a) SBE-Y photocatalyst, (b) Rh (0.2 mM), SBE-Y (5 µM), and NAD+ (0.4 mM) solutions, (c) energy level diagram for mechanistic studies.
Figure 7. XPS spectra of SBE-Y photocatalyst (a) C1s, (b) O1s, (c) S2p, and (d) Survey spectra obtained using XPS of SBE-Y.
Figure 8 (a-c). The transmission electron microscopy (TEM) along with HRTEM images of SBE-Y photocatalyst (d-g).
DETAILED DESCRIPTION OF THE INVENTION
In some embodiments of the present invention, using the procedure developed by Kolle and Grtzel, the hydridorhodium complex, RhCl, was created. Hexamethyldewarbenznene (HMDB), 100 mg, and RhCl3.3H2O, 500 mg, were combined in 15 mL of MeOH and agitated at 65 ? under N2 for 15 hours.
In some embodiments of the present invention, after the mixture had reached ambient temperature, the solvent was drawn off under vacuum. To take out excess hexamethylbenzene, the residue was purified by ether. These left oily red viscous materials, which were then extracted with CHCl3.
In some embodiments of the present invention, the mixture was evaporated under reduced pressure, dried in presence of MgSO4, and the residue was then recrystallized from CHCl3/benzene. When 2, 2'-bipyridine (2 eq.) was added, the suspension quickly cleared and a yellowish solution was produced.
Herein enclosed a sulfur-bridge eosin-Y (SBE-Y) photocatalyst synthesized via an in situ thermal polymerization process comprising of elemental sulfur (S8), eosin-Y, Hexamethyldewarbenznene (HMDB), 100 mg, and RhCl3.3H2O, 500 mg;
characterized by enhanced solar light absorption and efficient photocatalytic properties for CO2 transformation and C(sp³)-N bond activation.
A method for synthesizing the SBE-Y photocatalyst as claimed in claim 1, wherein the said method comprising the steps of:
Combining Hexamethyldewarbenznene (HMDB, 100 mg), and RhCl3.3H2O (500 mg) in 15 mL of MeOH and agitated at 65 ? under N2 for 15 hours;
Drawing off the solvent under vacuum after the mixture had reached ambient temperature;
Purifying the residue by ether to take out excess hexamethylbenzene;
Extracting these left oily red viscous materials with CHCl3;
Evaporating the mixtureunder reduced pressure, dried in presence of MgSO4, and the residue was then recrystallized from CHCl3/benzene;
Adding 2, 2'-bipyridine (2 eq.), and the suspension quickly cleared and a yellowish solution was produced;
Grinding (1.5 g) elemental sulfur powder and (500 mg) eosin- Y by utilizing a mortar and pestle for 20 minutes;
Keeping the mixture in the covered crucible and heated in a muffle furnace at 160 ºC for 2 hours; and
obtaining the 1.09 g light orange product as final product photocatalyst.
To regenerate NADH by photocatalysis, the QR was utilized to carry out the fixation of NAD+.
To regenerate NADH by photocatalysis, the NAD+ (0.62 mmol), Rh (0.31 mmol), photocatalyst (4 mg), and AsA (1.24 mmol) were the components of the reaction, which took place in 3.1 ml of NPB (100 mM).
The photocatalyst-enzyme system achieves a high conversion rate of CO2 to formic acid and demonstrates 1,4-NADH regeneration with efficiency greater than 86%.
The SBE-Y photocatalyst produced is employed in fine chemical synthesis applications, achieving conversion yields up to 99.9% under solar illumination.
The [Cp*Rh(bpy)Cl]Cl complex is used as a co-catalyst in the SBE-Y photocatalytic system to enhance the efficiency of CO2 conversion and C(sp³)-N bond activation reactions under solar light.
EXAMPLE 1
EXPERIMENTAL SECTION
Preparation of [Cp*Rh(bpy)Cl]Cl i.e.; B by precipitation method
Using the procedure developed by Kolle and Grtzel, the hydridorhodium complex, RhCl, was created. Hexamethyldewarbenznene (HMDB), 100 mg, and RhCl3.3H2O, 500 mg, were combined in 15 mL of MeOH and agitated at 65 ? under N2 for 15 hours. After the mixture had reached ambient temperature, the solvent was drawn off under vacuum. To take out excess hexamethylbenzene, the residue was purified by ether. These left oily red viscous materials, which were then extracted with CHCl3. The mixture was evaporated under reduced pressure, dried in presence of MgSO4, and the residue was then recrystallized from CHCl3/benzene. When 2, 2'-bipyridine (2 eq.) was added, the suspension quickly cleared and a yellowish solution was produced. (23, 24)
When Et2O was added to this sample, B precipitated. Yield: 302 mg (71%, based on compound A). 1H NMR (300 MHz, CDCl3): d=9.02 (d, 2H), 8.86 (d, 2H), 8.30 (t, 2H), 7.78 (t, 2H), 1.78 ppm (s, 15H, Cp*).
Crafting Sulfur-Bridge-Eosin-Y (SBE-Y) Photocatalysts for a CO2 transformation and C-N bond activation
The SBE-Y was prepared by using the in-situ thermal polymerization route. (25) Initially, 1.5 g of elemental sulfur powder and 500 mg of eosin- Y were grinded well utilizing a mortar and pestle for 20 minutes. Then, the mixture was kept in the covered crucible and heated in a muffle furnace at 160 ºC for 2 hours. Eventually, the 1.09 g light orange product was obtained (25). 1H NMR (300 MHz, CDCl3): d = 7.09-7.10 (s, 2H), 8.0 (d,1H), 7.62-7.69 (m, 2H), 6.12-6.18 (d, 1H), 6.18 ppm (s,1H).
Innovative SBE-Y photocatalyst sparks NADH regeneration
A solar pannel with a cut-off filter was utilized as a source of light for the photochemical regeneration of 1,4-NADH at ambient temperature inside a quartz reactor (QR). The following procedure was used to regenerate NADH by photocatalysis. The QR was utilized to carry out the fixation of NAD+. The NAD+ (0.62 mmol), Rh (0.31 mmol), photocatalyst (4 mg), and AsA (1.24 mmol) were the components of the reaction, which took place in 3.1 ml of NPB (100 mM). With the use of a UV-vis spectrophotometer (UV-1800, Shimadzu), regeneration of 1,4-NADH was tracked (Fig. 5a).
Quantum yield estimation.
The quantum yield (QY) was determined as per the reported given formula:
?y =2 (moles of NADH produced/moles of incident photon)
For the photocatalytic NADH regeneration process, the quantum yield of the SBE-Y polymeric framework photocatalyst was determined to be 0.146 (14.6%).
Solar Alchemy: Transforming CO2 into (HCOOH) formic acid, the fuel of tomorrow
The transformation of HCOOH from CO2 was also carried out in a QR under an inert environment at ambient temperature, with the light source being a solar lamp with a suitable cut-off filter. The photocatalyst (4 mg), Rh (0.31 mmol), NAD+ (0.62 mmol), and FateDH (3 units) were mixed in 3.1 mL of NPB (100 mM) with AsA (1.24 mmol). The QR was absorbed by solar light (light on) after purging CO2 for 1 hour in the non-existence of solar light (light off). HPLC was used to measure the quantity of formic acid. (22, 26-28)
EXAMPLE 2
RESULTS AND DISCUSSION
Harnessing SBE-Y Photocatalyst/Enzyme Synergy for CO2 Transformation and C-N Bond Activation
A schematic representation of the SBE-Y photocatalyst/enzyme attached system is a hybrid system that combines a photocatalyst (SBE-Y) and an enzyme to facilitate the formation of formic acid (HCOOH) from carbon dioxide (CO2) and transformation of the substrate into the product (C-N bond activation).
A solar light-harvesting substance called S-bridging eosin-Y (SBE-Y) is covalently joined to other substances. Photons are absorbed as they move between localized orbitals centered on E-Y. The generated electrons travel via a sulfur bridge to the electron mediator rhodium complex (Rh). An organometallic rhodium complex is quickly reduced after receiving the electron.(29) It, then removes a proton from an aqueous solution and converts NAD+ to NADH by adding electrons and a hydride. This completes the photocatalysis cycle.(28) The rhodium complex functions in this fashion to shuttle electrons between the SBE-Y photocatalyst and NAD+, demonstrating its effectiveness as a factor in the regeneration of the NADH cofactor. The CO2 substrate then uses up NADH to catalyze the enzymatic (formate dehydrogenase) formation of NADH to formic acid.(22, 30-32) The photo-regeneration of NADH can occur when the NAD+ released by the enzyme goes through a similar photocatalysis cycle. Thus, the two catalysis cycles are inextricably linked to producing formic acid from CO2 and the synthesis of fine compounds. By substituting elemental sulfur for bridge creation during in-situ thermal polymerization, the SBE-Y utilized as a photocatalyst in the photobioreactor was made. This approach increased the effectiveness of the solar energy harvesting ability of the newly designed SBE-Y photocatalyst for CO2 transformation and C-N bond activation, i.e.; fine chemical synthesis.
Unraveling the Solar-Powered Dance of Atoms: A Mechanistic Odyssey in C-N Bond Activation with Cutting-Edge Photocatalysts
We have given a solar mechanism for the classical reaction in the existence of an SBE-Y photocatalyst along with a solar light photoreactor based on literature reports and GC-MS analyses. The photocatalyst SBE-Y first absorbed solar light to create photoinduced electrons and holes.
The C-N coupling of aryl halides with pyrrole is brought about by the SBE-Y, which is stimulated by the creation of exactions (e, h+) by the captivation of solar light. The 1-chloro-benzaldehyde radical (A) is produced when 1-chloro-benzaldehyde undergoes a reductive electron transfer, followed by homolytic cleavage to produce benzaldehyde radical (B) and chloride anion. Immediately, photogenerated holes encourage the pyrrole's oxidation to form (C), and it then goes through deprotonation to make the intermediate (D). In order to create the anticipated C-N coupling (E) product, the intermediates (B) and (D) finally connected with one another.(33, 34) The intended C-N product, m/z 173.0753 (M+2), as well as the expected radical intermediates, benzaldehyde radical and pyrrole radical, were supported by GC-MS data.
A possible mechanism for sun light driven regeneration of enzyme cofactor 1,4-NADH with electron mediator [Cp*Rh(bpy)Cl]+
A possible mechanism of enzyme cofactor 1,4-NADH photoregeneration is depicted in Scheme 4. The sunlight absorbed by the sulfur-bridge-eosin-Y polymeric framework photocatalyst leads to photoexcitation of electrons followed by transfer to organometallic mediator rhodium complex (1). The rhodium complex (1) is formed by hydrolysis of [Cp*Rh(bpy)Cl]+. Thus, the reduced rhodium complex (2) is formed. A subsequent proton abstraction from aqueous medium leads to formation of hydride rhodium complex (3). At this stage, the hydride rhodium complex reacts with natural NAD+ leads to coordinative rhodium complex (4). The loss of one proton and two electrons regenerates the enzyme cofactor 1,4- NADH and starting oxidized organometallic rhodium complex (1). (35)
Unlocking the Secrets of Innovation: Exploring SBE-Y Photocatalyst's Crystal Clarity with PXRD Spectroscopy
Fig. 2 shows PXRD patterns of virgin E-Y and SBE-Y samples. As illustrated in Fig. 2, several different peaks in the 15-35° range clearly explain the polymeric framework's high crystallinity, indicating that the solvent-free sulfur-bridge-eosin-Y (SBE-Y) polymeric framework photocatalyst was prepared in situ thermal polymerization route for the first time. Two diffraction peaks at 2? values of 17.14o and 24.98° were seen on the overall patterns of sulfur-bridged samples. Surprisingly, this behaviour was also seen in sulfur-bridged polymeric semiconductor materials and was attributed to a drop in structural correlation length produced by particle size reduction.(36-39) Additionally, as per reported literature,(40) the well resolved diffraction peak of sulfur (2? = 23°-29°) exhibits orthorhombic structure with sharp crystalline peaks.(41, 42) The XRD pattern of SBE-Y (Fig. 2) photocatalyst exhibits quit matched peak at 23.14° and several peaks between 24.98°-28.9°, indicating the crystalline state and existence of S with reduced intensity in SBE-Y photocatalyst.
The crystalline development of our SBE-Y samples may be attributed to a normal thermal melt; the annealing polymerizing E-Y and S8 constituent can significantly alter the crystalline roughness of a polymeric framework semiconductor, such as framework ordering, chain orientation, and p-p interaction between the conjugated moieties units(37), which demonstrates in a high degree of orderliness of polymeric framework chains. In the preparation of SBE-Y, upon the incorporation of S8, the reaction part became more consistent due to S8 and E-Y acting as a molten flux to accelerate the in-situ polymerization. The effect of sulfur bridging on the morphology of SBE-Y will be further verified by SEM and TEM.
Optical Properties of Highly Efficient SBE-Y Photocatalyst Unlocks CO2 Transformation and C-N Bond Activation
UV-visible absorption spectroscopic measurement was used to assess the impact of the sulfur bridge on the SBE-Y framework photocatalyst semiconductor. A prominent absorption band at 541 nm and a higher absorbance comparable to an optical energy gap of 2.22 eV were seen in the UV-visible spectra of SBE-Y photocatalyst. Kubelka- Munk (KM) illustrated the optical band in Fig. 3 (a). On the other hand, using UV-Vis spectroscopy to determine the optical band gap of newly designed semiconductor SBE-Y framework photocatalysts is a key step in characterizing their electronic characteristics for diverse applications such as photocatalysis. The Tauc plot approach, which includes graphing (ahv)2 versus photon energy (hv/eV), where is the absorption coefficient, may be used to determine the band gap energy also. The x-axis intercept of this figure corresponds to the band gap energy (Eg). The formula is as follows: h=A(h-Eg), where A is a proportionality constant. To calculated the optical band gap energy (2.22 eV) of SBE-Y photocatalyst using the Tauc plot, as shown in Fig.3a inset (43), which is matching to calculated band gap by cyclic voltametric experiment (Fig. 6a). (44-48)
In theory, the SBE-Y photocatalyst's detected optical band gap should be adequet to carry out the solar light-driven reduction of the electron mediator rhodium complex Rh ([Cp*Rh(bpy)Cl]+; Cp* = pentamethylcyclopentadienyl, bpy = 2,2-bipyridine), which generates formic acid (31, 35) from CO2 and regenerates NADH. Studies employing the Fourier-transform infrared spectroscopy (FTIR) method provided strong evidence for the connection of eosin-Y and S8. According to Fig. 3(b). The E-Y (grey) monomer's FTIR spectrum exhibits peaks for the carboxylic and phenyl groups, respectively, at 1420 and 1464 cm-1 vibrations. The different peaks that appeared in the range of 3491 cm-1, 1746 cm-1, 1595 cm-1and 1210 cm-1 are assigned to -OH, -CO, C=C, and C-C bands respectively(24, 49) in the FTIR spectrum of E-Y. The Spectrum of S8 (blue) shows one peak at 467 cm -1 corresponding to the disulfide bond (-S-S-) bond. The spectra of SBE-Y (red) show peaks corresponding to about 3468 cm-1 which reveal the presence of -OH stretching vibrational mode of E-Y and the peaks corresponding to 467 cm-1 for the disulfide (-S-S-) stretching vibration band of S8. The appearance of a 467 cm-1 peak of the disulfide band in the newly synthesized SBE-Y framework photocatalyst clearly indicates the incorporation of E-Y and S8 (50), which is also confirmed by the X-ray photoelectron spectroscopy (XPS) studies.
The structure of the SBE-Y photocatalyst was confirmed by XPS, TEM, and HRTEM, studies. Further, the structure of SBE-Y material is confirmed by XPS analysis as well. The XPS analysis was performed to comprehend the surface chemistry and chemical composition of polymeric SBE-Y framework photocatalyst (Fig. 7a-d). The survey spectra (Fig. 7d) clearly showed the different element C1s, O1s, and S2p elements in newly designed the SBE-Y photocatalyst. The high-resolution C 1s spectra (Fig. 7a) were deconvolved over to resolve peaks at 284.2 eV, 284.7 eV, 285.6 eV and 288.6 eV. These peaks are assigned to aromatic C-C/C=C, C-S, C-O and O-C=O (51). The deconvolution XPS spectra of O 1s (Fig. 7b) profile shows binding energy peaks at 529.70eV, 530.90 eV and 531.49 eV. These peaks are ascribed to the C=O, O-C=O, and C-O. (51) Finally, the deconvolution spectra of S2p (Fig.7c) exhibits the binding energy peaks at 163 eV and 164.2 eV which is ascribed as C-S and S-S peak respectively.(52) Thus, the result of XPS confirmed the presence of the newly formed C-S bond and S-S in newly designed SBE-Y photocatalyst.
Transmission Electron Microscopy (TEM), High Resolution Transmission Electron Microscopy (HRTEM) and Scanning Electron Microscopy Along with Elemental Mapping Studies
The TEM, and HRTEM experiments were performed to clarify the microstructure of SBE-Y polymeric framework photocatalyst. The high-magnification TEM and HRTEM images, as displayed in Fig.8 a-f, clearly reveal the structure of the anchored sulfur (53, 54). The sulfur (55) anchored on the SBE-Y photocatalyst's structural characteristics are clarified by the high-resolution image displayed in Fig. 8a-g. As per reported literatures (55), the S (026) and S (040) planes are where the lattice fringes around 0.3 and 0.31 nm correspond, showing the clearly defined crystalline structure of sulfur (Fig.8f). Additionally, HRTEM and TEM images of SBE-Y polymeric framework photocatalyst (Fig. 8a-c) possess a chain of sulfur which homogeneously anchored on the surface of SBE-Y without any discernible aggregated sulfur particles being seen in the TEM and HRTEM image (Fig. 8a-h). On the other hand, the SEM and TEM will be used to support the effect of sulfur bridging on the morphology of the SBE-Y photocatalyst. The SBE-Y photocatalyst has a compact dendritic shape with well-developed branches, as seen by TEM (Fig. 4b), which is shown in the SEM image (Fig. 4c).
The bridge crystalline SBE-Y that is made from S8 and E-Y molecules often has this unique branching structure(56). The sulfur-bridged sample of SBE-Y's SEM image (Fig. 4b) shows a loosening branching morphology with a clear framework structure and pores, and the high-magnification(57) TEM image of SBE-Y also shows that the morphology matches the SEM image. The SEM image of SBE-Y is entirely different from the starting material (Fig. S2). This sulfur-bridging effect on E-Y's crystalline size is consistent with the XRD pattern's waning intensity (Fig. 2). The SEM was used to determine the elements such as carbon (C), oxygen (O), and sulfur (S) images of SBE-Y and E-Y photocatalyst, and Fig. 4(d-f) and Fig. S2 revealed that the elements (C, O, and S) and (C, O, and Br) were equally distributed throughout the substance. The elemental mapping images revealed the formation of the SBE-Y photocatalyst.
Adsorption and Desorption Studies by BET Technique
The nitrogen adsorption and desorption isotherms of the SBE-Y sample at 150? are shown in Fig. S1. At lower relative pressure, a minimal quantity of nitrogen is absorbed with a flat absorption and desorption isotherm curve till the relative pressure (P/Po) of 0.79. The isotherms of SBE-Y show a definite hysteresis loop in the P/Po range of 0.79-1.0 when the relative pressure is raised to 0.79, indicating the presence of mesopores.(58) The hysteresis loop in the reported polymeric material's isotherm is clearly smaller than that in the SBE-Y photocatalyst. It is slightly moved towards the higher P/Po, which suggests that the SBE-Y photocatalyst has a good pore volume and a more urbanised porous structure, which is consistent with its SEM image (Fig. 4c). The surface area of SBE-Y (13.98 m2/g) is larger than that of the reported sulphur-doped polymeric material as a result of the altered surface morphology. Therefore, a newly designed solvent-free synthesized SBE-Y photocatalyst-enzyme-attached artificial photosynthesis system will be superior to others(59) for photocatalytic reaction.
Harvesting Sunlight: Pioneering Selective Regeneration of cofactor 1,4-NADH, followed by its utilization in the exclusive production of formic acid (210.01 µmol) from CO2
To investigate the photocatalytic activity of E-Y and SBE-Y for the solar light-driven photo-regeneration of NADH, photocatalysis studies were carried out. A spectrophotometer was used to determine the concentration of photo-regenerated NADH(31, 60, 61). As demonstrated in Fig. 5a, SBE-Y is significantly effective for cofactor photoregeneration of 1,4-NADH with a temporal linearity of up to 86.81%.
However, the E-Y photocatalyst only regenerates NADH at a rate of 23.95% (Fig. 5a). As shown in Table S1, SBE-Y was significantly successful in NADH regeneration with constant accumulation up to 86.81% with time linearity. However, various photocatalyst (Table S1) afforded only less yields of NADH regeneration, due to slow recombination charges. Furthermore, the photocatalytic activity of S is very low in comparison to newly designed SBE-Y photocatalyst due to weak solar light absorption capacity (Fig. S6c) and molar extinction coefficient of elemental sulfur ( Fig. S6b). Therefore, the newly designed SBE-Y photocatalyst has excellent photocatalytic ability due to excellent light harvesting ability (Fig. 3a and Fig. 5a). Additionally, five cycles of NADH regeneration were used to test the SBE-Y film (?1×1 cm?^2 ) photocatalyst's stability and reusability. The fifth cycle produced 80.10% (92.27%) of NADH regeneration, compared to the first cycle's 86.81% (100%) achieved by the SBE-Y photocatalyst (Fig S6a). This extremely high photocatalytic activity suggests the existence of a stable, and reusable SBE-Y film (Fig.S7) photocatalyst for real-practical applications.

An additional experiment was carried out to explore the photocatalytic performance of E-Y and SBE-Y for the artificial photosynthesis of formic acid (COOH) from CO2 using solar light. HPLC (7890A, Agilent Technologies) was used to measure the quantity of formic acid. When SBE-Y is employed as a photocatalyst, the formic acid production increases linearly manner with reaction time, as shown in Fig. 5b. The efficiency of E-Y and SBE-Y in producing formic acid for 2 hours was 210.01µmol and 34.11µmol, respectively. These studies clearly show that the SBE-Y photocatalyst outperforms the other photocatalyst.(30, 31)
Unlocking the Power of Electrons: NADH Regeneration Mechanism Revealed Through Cyclic Voltammetry
The mechanism of the process can be better understood thanks to the use of cyclic voltammetry (CV). As a result, we explored the electrochemical characteristics of SBE-Y photocatalysts. The Rh and SBE-Y were found to have reduction potentials of roughly -0.71 V and close to -1.50 V, respectively (Fig. 6a). According to the published methodology, it is caused by interactions between the SBE-Y photocatalyst and Rh. (49, 62) A significant increase in the reduction potential with NAD+ was also exhibit in the SBE-Y-Rh complex, suggesting that the SBE-Y and Rh system was capable to catalyze the fixation of NAD+ (Fig. 6b).
Previous studies have shown that the catalytic effect of Rh causes a significantly higher rate of Rh fixation in the existence of NAD+.(62, 63) The potential was scanned at 100 mV s-1 utilizing glassy carbon, platinum, and calomel chloride as working, counter, and reference electrodes in NPB (100 mM). The catalytic ability of the SBE-Y-Rh complex may be attributed to the photoelectrical behavior of SBE-Y since Rh can readily accept the excited electron from SBE-Y. According to research,(28) the hybrid light-harvesting molecule's photoelectrical property results from the transfer of excited electrons from the V.B; to the C.B.;, which is followed by their entry into the rhodium complex. In this instance, the SBE-Y electron photoexcites from V.B (E = -5.87 eV) to C.B (E = -3.51 eV), where it then cascades into Rh (E = -3.96 eV) without emitting radiation (Fig. 6c). The Latimer diagram (Scheme S1) derived for SBE-Y photocatalyst by using values of V.B and C.B which is derived by CV experiment.(64, 65) This effective electron movement from the solar light active SBE-Y photocatalyst to the electrocatalytic Rh centre is made possible by the proximity and values. potential gradient between them. As a result, Rh electrically reduced, undergoes chemical protonation in aqueous media before being catalytically regenerated into NADH (86.81%) by interaction with NAD+.
CONCLUSION
In conclusion, we introduced a polymeric sulfur-bridge-eosin-Y (SBE-Y) photocatalyst for significant applications such as solar fuel production and the synthesis of fine chemicals. Through the use of spectroscopy, thermal analysis, and microscopy, the SBE-Y photocatalyst has been well characterized. Additionally, investigations on photo-electrochemistry have made it possible to assess photo-electrochemical characteristics and the basis of the photocatalytic ability of the photocatalyst. The photocatalyst-enzyme connected system for efficient and selective artificial photosynthetic formation of solar fuel (HCOOH) from CO2 and C-N bond activation uses the SBE-Y, a highly active solar light photocatalyst. This creates opportunities for sulfur-bridge-eosin-Y materials, particularly in the area of artificial photosynthesis. The search for a selective and highly efficient solar light dynamic material that acts as an SBE-Y photocatalyst in the regeneration of 1,4-NADH cofactor photoreactor and triggers enzymatic formation of solar chemicals as well as solar fuel from CO2 and synthesis of fine chemicals is one of the utmost difficult errands for practical utilize of the photocatalyst-biocatalyst integrated photosystem for artificial photosynthesis route. Thus, the current study effectively illustrates a new and promising artificial photosynthetic system based on sulfur-connected eosin-Y photocatalysts towards the ultimate objective of the utilization of solar energy in the tailor-made solar fuel from CO2 and synthesis of fine chemicals.
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,CLAIMS:1. A sulfur-bridge eosin-Y (SBE-Y) photocatalyst synthesized via an in situ thermal polymerization process comprising of
elemental sulfur (S8), eosin-Y, Hexamethyldewarbenznene (HMDB), 100 mg, and RhCl3.3H2O, 500 mg;
characterized by enhanced solar light absorption and efficient photocatalytic properties for CO2 transformation and C(sp³)-N bond activation.
2. A method for synthesizing the SBE-Y photocatalyst as claimed in claim 1, wherein the said method comprising the steps of:
a) Combining Hexamethyldewarbenznene (HMDB, 100 mg), and RhCl3.3H2O (500 mg) in 15 mL of MeOH and agitated at 65 ? under N2 for 15 hours;
b) Drawing off the solvent under vacuum after the mixture had reached ambient temperature;
c) Purifying the residue by ether to take out excess hexamethylbenzene;
d) Extracting these left oily red viscous materials with CHCl3;
e) Evaporating the mixtureunder reduced pressure, dried in presence of MgSO4, and the residue was then recrystallized from CHCl3/benzene;
f) Adding 2, 2'-bipyridine (2 eq.), and the suspension quickly cleared and a yellowish solution was produced;
g) Grinding (1.5 g) elemental sulfur powder and (500 mg) eosin- Y by utilizing a mortar and pestle for 20 minutes;
h) Keeping the mixture in the covered crucible and heated in a muffle furnace at 160 ºC for 2 hours; and
i) obtaining the 1.09 g light orange product as final product photocatalyst.
3. The method as claimed in claim 2, wherein to regenerate NADH by photocatalysis, the QR was utilized to carry out the fixation of NAD+.
4. The method as claimed in claim 2, wherein to regenerate NADH by photocatalysis, the NAD+ (0.62 mmol), Rh (0.31 mmol), photocatalyst (4 mg), and AsA (1.24 mmol) were the components of the reaction, which took place in 3.1 ml of NPB (100 mM).
5. The method as claimed in claim 2, wherein the photocatalyst-enzyme system achieves a high conversion rate of CO2 to formic acid and demonstrates 1,4-NADH regeneration with efficiency greater than 86%.

6. The method of as claimed in claim 2, wherein the SBE-Y photocatalyst produced is employed in fine chemical synthesis applications, achieving conversion yields up to 99.9% under solar illumination.
7. The method as claimed in claim 2, wherein the [Cp*Rh(bpy)Cl]Cl complex is used as a co-catalyst in the SBE-Y photocatalytic system to enhance the efficiency of CO2 conversion and C(sp³)-N bond activation reactions under solar light.

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