A Novel Study on 2-D Material in Photoelectrochemical Cell for the Conversion and Storage of Solar Energy

A photo-sensitizer made of graphene-based material (2-D) is used in concert with EDTA in photoelectrochemical solar cells to increase efficiency and storage capacity of solar energy in order to make a solar cell economically feasible. Photopotential and photocurrent are created at 1142mV and 960 μA, respectively. Photoelectrochemical cell have achieved a maximum power of 228.40 μW, a fill factor of 0.17, and a conversion efficiency of 4.38%. The cell storage capacity allows for a half power (t 1/2 ) level to be maintained for 1300 minutes. The electrical output of the photoelectrochemical cell has been observed to be influenced by a number of different factors.


INTRODUCTION
In future, there will be a huge global demand for energy.The energy production from the traditional methods arise pollution in the environment.Therefore, the field of renewable energy storage and focus field of the research. 1ence, the need of such devices for the effective use of renewable energy and such type of devices should be maximum efficient, cheaper-price and eco-friendly. 2Photoelectrochemical solar cells are the good devices for the production of high energy chemicals from the sun light.Due to their abundance, stability and eco-friendliness is most suitable and intense field of the research. 3 recent years, scientific community has founded that the study of carbon allotropes (carbon nanotube, diamond and fullerene) is more emerged area of research. 4Graphene is a two-dimensional (2D) carbon atom that was discovered in the year 2004. 5It is a monolayer and crystal honeycomb lattice structure.Konstantin Novoselov and Andre Geim awarded the 2010 Nobel Prize in Physics based on their research on two-dimensional graphene.It is called the mother of all graphite forms of carbon.To produce low-cost, lightweight, and high-performance composite materials, researchers from all over the world are still exploring for new dimensions.The basic building block for other allotropes is thought to be graphene. 6Carbon atoms are arranged in a two-dimensional honeycomb lattice called graphene, which can also be wrapped into a zero-dimensional material called fullerene.Carbon atoms are arranged in a honeycomb lattice on a 2-D plane to form graphene. sp 2 orbitals are created through the hybridization of three carbon atomic orbitals.Covalent bonds are created between these sp 2 orbitals and the carbon atoms.The hybridised sp 2 orbitals and the 1.42 separation between the carbon atoms create the hexagonal planar structure known as the honeycomb lattice.Graphene's crystal structure gives rise to certain outstanding properties. 7n the past several years, the arena of nanoscience and nanotechnology has emerged significantly and its application is increasing continually in different industries. 8The interest in nanoscience has grown in academia and business since the creation of monolayer graphene.Researchers from all over the world are now very interested in graphene, which has been dubbed a "wonder substance" because of its excellent mechanical and functional qualities and high potential for creating advanced gadgets.Materials made of graphene have a lot of potential for use in electromechanical devices. 9ientists have been attracted to the study of graphene and its derivatives such as graphene oxide (GO), reduced graphene oxide (rGO) because of their good properties, including their large specific surface area, strong chemical stability, good electrical conductivity, and potential optical, mechanical, electrical, and structural properties. 10As a result, the nanocomposite mater ials based on graphene have good conductivity for energy storage and conversion due to all of the above features. 113][14] In this research work, we apply r-GO dispersion solution in photoelectrochemical solar cells to investigate solar energy conversion and storage.

MATERIALS AND METHOD
This section describes the materials that are used for the synthetization of graphite powder to graphite oxide and reduced graphite oxide, preparation for other solutions.Table 1 shows the chemicals and their specifications used for solutions.

Synthesis of Graphite to Graphite oxide (GO)
In today's era, it is extremely difficult to manufacture graphene on a large scale.GO can be produced by oxidizing graphite, using a variety of techniques, including those shown by Brody, Staudenmaier's and Hummer.For the preparation of GO, the Modified Hummers method has been employed most frequently. 15 a typical experiment, 20 g of graphite powder (Merck) is mixed with NaNO 3 (10 g) to form a homogeneous solution.Now after this take 450 mL of concentrated H 2 SO 4 (96% w/w) in a beaker of 5 L capacity.Now, an ice bath is used to cool the solution and keep the temperature below 5 o C.Under steady stirring with a stirrer coated in Teflon, the two ingredients above were progressively combined.Additionally, while keeping the reaction mixture's temperature to below 5 o C, gradually, 60 g of KMnO 4 (Merck) were added.The reaction mixture was removed from the ice bath after the KMnO 4 addition was finished and kept constantly stirring.The reaction mixture then appeared to transform into a brownish-gray paste.The reaction vessel's temperature was raised to 95°C by slowly adding 1000 mL of de-ionized water.Further dilution of the reaction mixture was accomplished using de-ionized water.The un-reacted MnO 4 -and by-product MnO 2 were then converted into soluble Mn 2+ by reacting it with 6% H 2 O 2 .The resulting brown solution was dried at 50°C in a vacuum oven after being vacuum filtered and rinsed with diluted HNO 3 to eliminate any remaining metal ions from the graphite oxide. 16raphene oxide (GO) must be reduced in order to regain its thermal and electrical properties because it's thermally unstable and electrically insulating.Graphite oxide is exfoliated and reduced to reduced graphene oxide predominantly through chemical processes Figure 1.
solvents.After that, the solvent was mixed, and the mixture were sonicated for an hour in an ultrasound bath cleaner. 20To obtain a nominal concentration of 0.5 mg mL -1 for all of the solvents, a specified quantity of rGO power (5 mg) was added to a predetermined volume of solvent (10 mL), allowing direct comparison between the dispersion behaviours of the various solvents.Acetone, methanol, ethanol, and 1-propanol were the organic solvents used to test rGO dispersions. 21e have shown that the solubility of rGO varies depending on the solvent, being 0.9, 0.52, 0.91, and 1.2 correspondingly. 22Compared to other organic solvents, 1-propanol has superior solvent solubility.The rGO and 1-propanol dispersions solution remained stable for several days without noticeable sedimentation.

Experimental Section of the photoelectro chemical cell
4][25] In the H-shaped tube, the solution of graphene dispersed, NaOH and Reductant (EDTA) was filled in the proper manner.The total volume of the above tube after filling the solution was always 30 mL.After that in the H-shape glass tube which has a transparent window for the illumination, a platinum electrode was dipped with the saturated calomel (SCE) electrode combination.A digital multimeter was connected to the terminals of the electrodes.The apparatus measured the dark potential inside the chamber of total darkness.A lamp (tungsten) serving as the light source was exposed through the clear window of the apparatus.To filter infrared radiation, the light source and the illuminated chamber were separated by a water filter.The final step of the experiment was measuring the potential and current produced by the experimental setup using a digital multimeter.[28][29]

Mechanism of Current Generation
An electricity generator powered by (cyclic) light is the photoelectrochemical system.For numerous cycles, it has been observed that the

Synthesis of Graphene oxide (GO) to reduced Graphene oxide (rGO)
To produce chemically reduced graphene oxide (rGO), graphite oxide was first converted into a stable colloidal dispersion and then employing reducing chemicals to reduce the exfoliated graphite oxide.Exfoliating graphite oxide with ultrasonication in either water or alcohol can result in the formation of a stable GO dispersion.r-GO was created by reducing agents reacting with graphene oxide.For this investigation, r-GO was obtained using hydrazine hydrate.The above suspension was once more sonicated for 2 h to produce rGO.At room temperature, hydrazine hydrate was gradually added drop by drop to the exfoliated graphite oxide suspension.The reduction took place for 1 h at 100 o C For this sample, hydrazine hydrate and GO were maintained at a weight ratio of 9:7.The resulting black precipitates were then rinsed with a 1M HCl solution and filtered through cellulose filter paper.[19]

Preparation of Solutions
All solutions are created with doubledistilled water.The creation of all chemical stock solutions involves direct weighing.We employed several solutions, including.rGO dispersion solution, 1N NaOH solution, and .01MEDTA.The dry product was first crushed with a mortar and pestle to prepare rGO dispersions in various photoelectrochemical behaviour is reversible. 30In the cell, the reducing agents and their oxidised residues provide as the electron carriers.[33] A substance becomes more electrically conductive when electromagnetic radiation, such as visible light, infrared light, and UV light, is absorbed.A phenomenon of both optics and electricity is photoconductivity.When light is absorbed, more free electrons and holes become available, increasing the electrical conductivity of a graphene material.The term "photocurrent" refers to the flow of electricity caused by photoconductivity or the photovoltaic effect.Here, photoconductivity is the generation, migration, and recombination of free carriers in the conduction and valence bands is used to describe the photovoltaic process.Graphene's strong charge carrier mobility, wide range of light absorption, and ultrafast carrier dynamics make it a potential material for the production of high-performance photoelectrons.
The variation of photopotential of dispersed solution of rGO with EDTA system with respect to time is graphically represented in Figure 3. Where: rGO = reduced graphene oxide, rGO*=Excited reduced graphene oxide, rGO -=Semi form of reduced graphene oxide, R=reductant molecule, R+=Oxidized form of the reductant.

Study of photo potential with time during the charging of the cell
The changes in potential of the system with time were measured at different time intervals by digital multimeter.During the charging of a photoelectrochemical cell, the photopotential is gradually increased until it reaches its maximum value, after which it remains relatively constant, which is known as maximum photo potential (V OC ) and the curve is maximum increase and it remains relatively constant then decrease open circuit potential (V OC ).The extreme value between the potential and current readings was recorded when a digital multimeter connected to the circuit via a carbon pot (log 470K) applied an external load.Current-potential (i-V) characteristics of the photoelectrochemical cells are graphically represented in (Fig. 4) using an EDTA and dispersion solution of reduced graphene.In this i-v curve, we observed a point that is referred to the maximum power at power point (P PP ) since it is where the result of maximum current and minimum potential is found.The following formula is used to obtain the fill-factor at power point when the potential reading is greatest and the current reading is zero.

Study of photopotential, photocurrent and power at power point of the cell
Then key insert in connecting switch 20 μA difference in similar photocurrent in decrease and photo potential in continuously increase and photopotential and photocurrent are multiplied obtain power and after then we reach maximum power of the cell.
Graphical representations of the photopotential, photocurrent, and power at power point of cell for photoelectrochemical cells with dispersed solution-EDTA system Figure 5.

Storage capacity of the cell
T h e s y s t e m ' s s t o r a g e c a p a c i t y (performance) is measured when the illumination is turned off as soon as the potential reaches a constant value and after applying an external load (which needs current at the power point).The storage capacity is measured in the form of t 1/2 , or the time it takes for the greatest power to decrease to half in complete darkness.The observed half-life of the cell is 1300 min, as shown graphically in Figure 6. the system's conversion efficiency, which is calculated to be 4.38% using the photocurrent and photopotential values at the power point and the incident power of radiations.
Conversion efficiency=(V PP ×i PP )/(P×A) ×100% (7)   Photo potential (DV)=V OC -V Dark (8)   Here, open circuit voltage, potential at power point, short circuit current, current at power point, power of incoming light, electrode area, and dark potential are referred to V oc , V PP , i sc , i PP , P, A, dark V Dark as, respectively.

variation effect of photosensitizer (r-GO dispersed solution) on Photoelectrochemical cell
The effect of r-GO dispersed solution on photopotential and photocurrent was investigated.When the concentration of r-GO dispersion solution is increased, the photopotential, photocurrentand power of cellto their maximum value at 2 mL solution of rGO, after the obtain parameter are maximum and then decrease at given point in the studies of rGO and dispersion solution.
After varying the r-GO dispersed solution, it was observed that the lowest value shown in Table 5 for 1 mL r-GO dispersed solution, which has the lowest photopotential and photocurrent values at 432 mV and 642 μA, respectively.In a similar manner, the photopotential and photocurrent values at 2 mL are 1136 mV and 960 μA, respectively, while the power value is 1090.56μW the highest in the graph.
In Fig. 7 show graphical representations of photo potential, photocurrent, and power of the cell with graphene distributed solution.

Conversion efficiency
The for mula is used to deter mine

Performance of the Cell
The photoelectrochemical cell's total performance has been measured, and it has attained an impressive stage in terms of storage capacity, electrical output, conversion efficiency, and initial photocurrent generation.

CONCLUSION
Fossil fuels industries account for a sizable share of global electricity production.Although the observed conversion efficiency of PG cells is fairly low (4.38%) as compare to the theoretical conversion efficiency of these cells is about 24-35%.Periodically, there are discussions on this challenge to photogalvanic cell development.To hasten the implementation of climate change measures, the world will need to dramatically reduce its usage of coal and oil over the coming decades.At the moment, hydrocarbon materials provide about more than half of the world's energy needs.r-GO dispersed solution, NaOH, and EDTA are novel system for solar cell is more effective.The r-GO dispersed solution has increased the storage capacity and conversion efficiency of Photoelectrochemical cell that happens as a result of the photo galvanic action on the working electrode.
The conversion efficiency, t 1/2 , and fill factor for the r-GO dispersed solution, NaOH, and EDTA novel systems are recorded as 4.38%, 1300 min and 0.17, respectively.Power point applications for the r-GO dispersed solution, NaOH, and EDTA system are current at short circuit, potential at open circuit, and power point of cell (pp) were also tested, and the results are as follows: 960 mV, 1142 mV, 228.40 μW.

Fig. 2 .
Fig. 2. Scheme of mechanism of current generationThese observations lead to the following mechanism is described for the production of photocurrent in the photoelectrochemical cell's:

Fig. 3 .
Fig. 3. variation of Potential with Time Current-voltage (i-v) characteristics of cell A digital multimeter (with one circuit closed) and a digital multimeter are used to measure the short circuit current (i sc ) and open circuit voltage (V OC ) in PECs (photoelectrochemical cells) (with the other circuit open).Close circuit potential is present when a key is put into the

Fig. 5 .Fig. 6 .
Fig. 5. variation of Potential and Power with Current (a) (i-v) Characteristic of the Cell, (b) Power v/s Current

Fig. 7 .
Fig. 7. variation of Potential, Current and Power with r-GO Dispersed solution