The present disclosure relates to a process for manufacturing of graphene nanofibers (GNFs) from cotton sources by avoiding usage of any toxic chemical or gas during the synthesis process.

BACKGROUND OF THE INVENTION

The present form of the photovoltaic device generally made up of rigid structure, which makes them unsuitable for the flexible applications, where flexibility understands as priority matter. Therefore, the development of flexible organic photovoltaic attracts the researchers to give a fruitful solution for the flexible energy conversion technologies. Although many flexible thin films based photovoltaic devices has been formed, but they do not meet with the requirement of electronic textile, which needs ultra-flexible devices. As a result, attention has been drawn towards the flexible fibre like wires which could be easily fabricated by conventional textile. Recently, wire shaped photovoltaic has shown their potential for the electronic textile, where they could be used as electric generator for the generation of electricity.

However, these photovoltaic wires are suffering from poor device parameters in comparison to the conventional photovoltaics due to the poor performance of the electrode materials. Generally metal wires, carbon fibres and conjugated conducting polymer-based materials are generally employed as electrode materials in photovoltaic wire. However, the performance of these photovoltaic wires could be improved by improving a smoother interface, and conductivity within the fibre-based electrodes of these photovoltaic wires. In this regard, graphene has showed its potential candidacy to use them as electrode materials in photovoltaic wire. Graphene belongs to the family of 2D carbon nanomaterials, where each carbon atom possessed sp2 hybridization arranged in honeycomb lattice. Because of extraordinary electrical, optical and mechanical properties, graphene has shown its potential candidacy various optoelectronic applications. Generally, the macroscopic assemblies of the 2D and 3D graphene nanosheets were prepared by using simple solution filtration method and hydrothermal method, but the fabrication of these 2D graphene nanosheets into 3D graphene nanofibers (GNFs) emerge as an extraordinary challenge. There are several applications of (GNFs) have been reported in which the (GNFs) have been used for the electronic textile applications. These applications include the highly flexible and electrically conductive flexible conductors, GNFs based actuators, GNFs based motors, GNF based DSSC photovoltaic wire, GNFs based supercapacitors and many more.

However, several efforts have been made in order to synthesize (GNFs). In this regard, Gao et al. showed the preparation of graphene oxide (GO) fibres through coagulation method for the scalable synthesis of GO fibres, although the mechanical strength becomes an issue in this method. Yu et al. demonstrated neat and macroscopic graphene fibres (GFs) spun from GO suspensions followed by chemical reduction. This wet spinning technique showed the possibility of making GF in laboratory scale method along with the possibility of in-situ fabrication with organic and inorganic moiety, however the method was found to limited within the laboratory scale.

The previously existing state of art showed the wet techniques for the fabrication of GNFs from graphene oxide methods. In all of these methods, synthesis of graphene oxide is a necessary step, which takes a strong media of acidic and toxic chemicals, which is one of the drawbacks of the process. Further, additional step needs mechanical processing for the fabrication of the GNFs, while another method includes the hydrothermal synthesis of GFs by using small pores capillaries system. Although the process can produce more than >6m GF, but the handling of the process needs skilful hands for the tackling of the glass capillary to get uniformity within the products.

In the view of the forgoing discussion, it is clearly portrayed that there is a need to have a process for manufacturing of graphene nanofibers (GNFs) from cotton sources.

SUMMARY OF THE INVENTION

The present disclosure seeks to provide a process for manufacturing of graphene nanofibers (GNFs) from cotton fibre (CF) and cotton rope (CR) to develop any kind, any shaped GNFs by simple tuning the shape of cotton source.

In an embodiment, a process for manufacturing of graphene nanofibers (GNFs) from cotton sources is disclosed. The process includes soaking cotton fibre (CF) and cotton rope (CR) in ethyl alcohol and isopropyl alcohol to develop rapid carbon skeleton and flexibility within GNFs. The process further includes placing alcohol-soaked CF and CR inside a hydrothermal reactor at 150°C temperature for 5 hours for initiating nucleation of the carbon skeleton for growth of graphene nanosheets. The process further includes performing high temperature pyrolysis for hydrothermally treated CF and CR inside tube furnace in the inert atmosphere of N2 gas at the temperature of 800°C with the heating rate of 5°C/min of 40 min for manufacturing of graphene nanofibers (GNFs).

In an embodiment, at temperature most of the carbon converts into the network of mixed form of the sp2 and sp3 hybridized carbon atoms, where the percentage of sp3 hybridized carbon atoms attained more value than the sp2 hybridized carbon atoms as mainly the possible carbon skeleton developed in this phase is belong to the formation of the graphene oxide.

In an embodiment, form of the graphene must be conductive for applications related to energy conversion and storage, which comes only when there is the high percentage of sp2 hybridized carbon atoms.

In an embodiment, high temperature pyrolysis process from 150°C to 800°C begins the development of graphitic nature with the skeleton of CF and CR.

In an embodiment, temperature of range 150°C to 800°C, bio-fuel also obtained as by product up to 400°C, while leaving behind carbon skeleton, which developed in graphitic form beyond this temperature.

In an embodiment, the scalable shape selectivity of the cotton-based materials are used to develop GNFs.

An object of the present disclosure is to control band gap of GNFs by tuning the temperature process.

Another object of the present disclosure is to avoid any toxic chemical or gas during the synthesis process.

Yet another object of the present invention is to deliver an expeditious and cost-effective process to develop any length electrode wire for the various applications including DSSC photovoltaic wire.

To further clarify advantages and features of the present disclosure, a more particular description of the invention will be rendered by reference to specific embodiments thereof, which is illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail with the accompanying drawings.

BRIEF DESCRIPTION OF FIGURES

These and other features, aspects, and advantages of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

Figure 1 illustrates a flow chart of a process for manufacturing of graphene nanofibers (GNFs) from cotton sources in accordance with an embodiment of the present disclosure;
Figure 2 illustrates a flow chart of synthesis process in accordance with an embodiment of the present disclosure;
Figure 3 illustrates Raman spectra of GNFs obtained from cotton fiber (CF) in accordance with an embodiment of the present disclosure;
Figure 4 illustrates Raman spectra of GNFs obtained from cotton rope (CR) in accordance with an embodiment of the present disclosure;
Figure 5 illustrates (a) FT-IR spectra of GNFs from CF; (b) FT-IR spectra of GNFs from CR in accordance with an embodiment of the present disclosure;
Figure 6 illustrates FESEM images of GNFs from CF (a-c); and diameter profile of GNFs (d-e) in accordance with an embodiment of the present disclosure;
Figure 7 illustrates 3D surface plot of GNFs from CF (a-c); Hill view of the various forms of GNFs in accordance with an embodiment of the present disclosure;
Figure 8 illustrates High magnification surface analysis of GNFs form CF (a-b); 3D surface plot morphology of the GNFs (c-d); Hill view of the GNFs (e-f) in accordance with an embodiment of the present disclosure;
Figure 9 illustrates FESEM images of GNFs from CR (a-c); and diameter profile of GNFs (d-e) in accordance with an embodiment of the present disclosure;
Figure 10 illustrates 3D surface plot of GNFs from CR (a-c); Hill view of the various forms of GNFs from CR in accordance with an embodiment of the present disclosure;
Figure 11 illustrates FESEM images of GNFs from CR at high magnification in accordance with an embodiment of the present disclosure; and
Figure 12 illustrates UV-Visible spectra of the GNFs from CF in accordance with an embodiment of the present disclosure.

Further, skilled artisans will appreciate that elements in the drawings are illustrated for simplicity and may not have necessarily been drawn to scale. For example, the flow charts illustrate the method in terms of the most prominent steps involved to help to improve understanding of aspects of the present disclosure. Furthermore, in terms of the construction of the device, one or more components of the device may have been represented in the drawings by conventional symbols, and the drawings may show only those specific details that are pertinent to understanding the embodiments of the present disclosure so as not to obscure the drawings with details that will be readily apparent to those of ordinary skill in the art having benefit of the description herein.

DETAILED DESCRIPTION:

For the purpose of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated system, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.

It will be understood by those skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the invention and are not intended to be restrictive thereof.

Reference throughout this specification to “an aspect”, “another aspect” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. Thus, appearances of the phrase “in an embodiment”, “in another embodiment” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.

The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such process or method. Similarly, one or more devices or sub-systems or elements or structures or components proceeded by "comprises...a" does not, without more constraints, preclude the existence of other devices or other sub-systems or other elements or other structures or other components or additional devices or additional sub-systems or additional elements or additional structures or additional components.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The system, methods, and examples provided herein are illustrative only and not intended to be limiting.

Embodiments of the present disclosure will be described below in detail with reference to the accompanying drawings.

Referring to Figure 1, a flow chart of a process for manufacturing of graphene nanofibers (GNFs) from cotton sources is illustrated in accordance with an embodiment of the present disclosure. At step 102, the process 100 includes soaking cotton fibre (CF) and cotton rope (CR) in ethyl alcohol and isopropyl alcohol to develop rapid carbon skeleton and flexibility within GNFs. The precursor ethyl alcohol and isopropyl alcohol is soaked uniformly for a user defined interval for good yield.

At step 104, the process 100 includes placing alcohol-soaked CF and CR inside a hydrothermal reactor at 150°C temperature for 5 hours for initiating nucleation of the carbon skeleton for growth of graphene nanosheets.

At step 106, the process 100 includes performing high temperature pyrolysis for hydrothermally treated CF and CR inside tube furnace in the inert atmosphere of N2 gas at the temperature of 800°C with the heating rate of 5°C/min of 40 min for manufacturing of graphene nanofibers (GNFs).

In an embodiment, at temperature most of the carbon converts into the network of mixed form of the sp2 and sp3 hybridized carbon atoms, where the percentage of sp3 hybridized carbon atoms attained more value than the sp2 hybridized carbon atoms as mainly the possible carbon skeleton developed in this phase is belong to the formation of the graphene oxide.

In an embodiment, form of the graphene must be conductive for applications related to energy conversion and storage, which comes only when there is the high percentage of sp2 hybridized carbon atoms.

In an embodiment, high temperature pyrolysis process from 150°C to 800°C begins the development of graphitic nature with the skeleton of CF and CR.

In an embodiment, temperature of range 150°C to 800°C, bio-fuel also obtained as by product up to 400°C, while leaving behind carbon skeleton, which developed in graphitic form beyond this temperature.

In an embodiment, the scalable shape selectivity of the cotton-based materials are used to develop GNFs.

Figure 2 illustrates a flow chart of synthesis process in accordance with an embodiment of the present disclosure. Graphene nanofibers (GNFs) have shown great interest for energy conversion and storage applications. However, the demand of large scale and rapid production of GNFs still facing challenges. In this regard, cotton-based materials showed their candidacy to scale up the production of GNFs through the pyrolysis techniques. The shape selectivity of the cotton-based fibres gives an advantage to scale up the synthesis of the GNFs in the desired shape. Therefore, the present synthesis method showed the scalable shape selectivity of the cotton-based materials to develop GNFs. Two cotton-based materials were selected in the present work, which showed the importance of the shape selectivity of the cotton-based precursors for the synthesis of the GNFs. Cotton fibres (CF) and cotton rope (CR) were investigated in order to synthesize GNFs of different shape and size. Both the precursors i.e., CF and CR were firstly immersed into solution of ethyl alcohol and iso propyl alcohol. The alcohol-based solution was used in order to develop rapid carbon skeleton and flexibility within the GNFs. As the process used pyrolysis techniques at high temperature, rigid carbon skeleton mainly developed with the presence of the alcohol-based media. So, when the alcohol-soaked CF and CR were placed inside the hydrothermal reactor at the temperature of 150°C for 5 hours, nucleation of the carbon skeleton starts for the growth of the graphene nanosheets. At this temperature most of the carbon converts into the network of mixed form of the sp2 and sp3 hybridized carbon atoms, where the percentage of sp3 hybridized carbon atoms attained more value than the sp2 hybridized carbon atoms as mainly the possible carbon skeleton developed in this phase is belong to the formation of the graphene oxide. However, for the applications related to energy conversion and storage, the form of the graphene must be conductive, which comes only when there is the high percentage of sp2 hybridized carbon atoms. Therefore, high temperature pyrolysis was done for the hydrothermally treated CF and CR inside the tube furnace in the inert atmosphere of N2 gas at the temperature of 800°C with the heating rate of 5°C/min of 40 min. The high temperature pyrolysis process from 150°C to 800°C begins the development of graphitic nature with the skeleton of CF and CR. Further, in this temperature of range 150°C to 800°C, bio-fuel also obtained as by product up to 400°C, while leaving behind carbon skeleton, which developed in graphitic form beyond this temperature. Finally at the temperature of 800°C, a full skeleton of the graphene nanosheets in the form GNFs were obtained which were characterized by Raman spectroscopy, which is popularly known to investigate graphitic products.

Figure 3 illustrates Raman spectra of GNFs obtained from cotton fiber (CF) in accordance with an embodiment of the present disclosure. Figure 3 showed the Raman spectra fitted with Lorentzian function of the CF showed two well-known peaks at 1331 cm-1 and 1583 cm-1 corresponding the D and G band of the graphene nanosheets in GNFs, where the D band showed the defects presents within the GNFs because of the presence of sp3 hybridized carbon atoms, which were developed during the development of the GNFs from CF, while the G band demonstrates the presence of graphitic structure because of the presence of sp2 hybridized carbon atoms in GNFs and showed the Ist order scattering of the E2g phonons of the in plane sp2 hybridized carbon atoms. Further, the intensity of D band directly relates to size of the in plane sp2 C domains, where the high intensity of D band indicates large size of the sp2 C domains within the GNFs. The average size of these sp2 C domains depends upon the ratio of ID/IG ratio, which is inversely proportional to the average size of sp2 C domains within the graphene nanosheets. The ID/IG ratio for the GNFs from CF was found to be 0.979, which is higher than the ID/IG ratio of graphite, thereby showed the more sp2 C clusters because of the generation of new carbon domains and more concentration of defect densities duration the formation of GNFs. Further, two other peaks were also observed at 2731 cm-1 and 2932 cm-1 corresponds to 2D and D+G bands. The appearance of these bands occurred due the process of double resonance. Further, the presence of the 2D band showed that each GNFs made up of few graphene nanosheets, while a higher intensity D+G band showed lesser number of disorderness of the graphene nanosheets within the GNFs.

Figure 4 illustrates Raman spectra of GNFs obtained from cotton rope (CR) in accordance with an embodiment of the present disclosure. In the case of the GNFs obtained from CR, the Raman spectrum also exhibit D and G band at 1333 cm-1 and 1595 cm-1, which confirms the presence of graphene nanosheets within the GNFs. Similarly, these bands also showed the defect concentration and graphitic nature of GNFs. However, GNFs obtained from CR demonstrated low value of ID/IG= 1.061, which showed presence of more sp2 C domains in the GNFs in comparison to GNFs obtained from the CF. The intensity of the D band also depicted the presence of more sp2 carbon atoms within the CNFs. Further, due the double resonance process, 2D band also appears at 2682 cm-1 corresponds to presence of few layers’ graphene nanosheets in each GNFs, while the presence of the combination of D+G band at 2901 cm-1 strongly indicates the smaller disorderness of the graphene nanosheets within the GNFs obtained from CR.

Figure 5 illustrates (a) FT-IR spectra of GNFs from CF; (b) FT-IR spectra of GNFs from CR in accordance with an embodiment of the present disclosure. Further, FI-IR investigations were carried out in order to investigate the presence of various functional groups within these GNFs obtained from CF and CR. Figure 5(a) showed the FT-IR spectra of GNFs from CF depicted the strong and broad peak at 3437 cm-1, weak peak at 2926 cm-1, medium and sharp peak at 1631 cm-1, weak peak at 1388 cm-1, weak and broad peak at 1028 cm-1 and weak peak at 615 cm-1 corresponds to the –OH stretching, -CH stretching, -C=C- stretching, -CH bending, -C-O stretching and (.....), while Figure 5 (b) demonstrates the FT-IR spectra of GNFs from CR showed strong and broad peak at 3434 cm-1, weak peaks at 2924 cm-1 and 2856 cm-1, weak peak at 1734 cm-1, medium and sharp peak at 1636 cm-1, sharp and medium peak at 1384 cm-1 and 1055 cm-1 corresponds to the –OH stretching, -CH stretching, -C=O stretching, -C=C- stretching, -CH bending and –C-O stretching respectively.

Figure 6 illustrates FESEM images of GNFs from CF (a-c); and diameter profile of GNFs (d-e) in accordance with an embodiment of the present disclosure. After analyzing the various functionalities within the GNFs, surface morphologies and fibre dimensions were analyzed from FESEM analysis. FESEM images of the GNFs form CF were recorded at different magnifications. Figure 6 (a-c) showed the FESEM images at the magnification of 50µm, 30 µm and 10 µm. FESEM images clearly depicted fibre like morphology, where the diameter of GNF ranging from 2-5 µm Figure 6 (d-f).

Figure 7 illustrates 3D surface plot of GNFs from CF (a-c); Hill view of the various forms of GNFs in accordance with an embodiment of the present disclosure. Further, the FESEM images of the GNFs from CF showed distinctive morphology with random alignment of GNFs, where GNFs aligned with each other in different phases which includes two or more asymptotically GNFs, overlapped GNFs and cross-linked GNFs. Figure 7 (a-c) showed the 3D surface plot of asymptotically GNFs, overlapped GNFs and cross-linked GNFs, while Figure 7 (d-f) demonstrates the hill view surface plot of these kinds of GNFs. These figures clearly depicted that each GNFs either singly folded or bi-folded, makes a well-established 3-D network for the smother passage of the charge transportation. Further, at some of the places of FESEM images, a single thread of GNF was kept in between two other GNF bounded spirally with each other, which showed a strong 3D network for various energy conversion and storage applications. This kind of morphology may be attributed because of the predefined shape selectivity of cotton fibers. It may be possible that during the transformation, the skeleton of fibrous networks retains its shape.

Figure 8 illustrates High magnification surface analysis of GNFs form CF (a-b); 3D surface plot morphology of the GNFs (c-d); Hill view of the GNFs (e-f) in accordance with an embodiment of the present disclosure. Further, the surfaces of each GNF were also investigated at the higher magnification of 1µm and 400nm. At high magnification, the surface of a randomly selected GNF showed the outer surface of graphene nanosheets. The outer surface of the graphene nanosheets depicted large clusters of the graphitic sheets, where the edges of the graphene nanosheets found with wrinkle type morphology. Further, each GNF well connected with each other as depicted by the 3D surface plot. Further hill view of the surface of GNF showed that each at some of places, again these GNFs were divided into small fragments to develop a channel of tiny GNFs i.e. it may be possible that each GNF may consists several other small range GNFs (Figure 8 (a-f)). Therefore, from this point of view, it seems that each tiny fragment of GNF behave like as the building block for the development of macro form of GNFs.

Figure 9 illustrates FESEM images of GNFs from CR (a-c); and diameter profile of GNFs (d-e) in accordance with an embodiment of the present disclosure. Similarly surface morphology of the GNFs obtained from CR also analyzed from FESEM images to investigate GNFs from CR. Figure 9 (a-c) showed the FESEM images of the GNFs from CR at different magnification of 30 µm, 10 µm and 4 µm respectively. All of these images clearly depicted fibre like morphology with the average diameter range of 2-5 µm as shown by the plot profile diagram for the measurement of diameter of GNFs from CR Figure 9 (d-e).

Figure 10 illustrates 3D surface plot of GNFs from CR (a-c); Hill view of the various forms of GNFs from CR in accordance with an embodiment of the present disclosure. Unlike the GNFs obtained from CF, the GNF form CF showed directional behaviour due to shape selectivity cotton rope. Each of the GNF showed horizontal alignment with almost separated morphology. Further, 3D surfaces plot and hill view of GNFs clearly depicted that mostly distinctive GNFs exist with each other (Figure 10 (a-c and d-f)). No crossover or overlapped morphology in between two GNFs was seen, as found in the case of GNFs from CF. However, GNF with wrinkled morphology was seen in some of the GNF. The 3D surface plot of the GNFs depicted that the GNFs adjacent to each other connected with each other with the outer surface of the graphene nanosheets. The graphene nanosheets thus formed shaped in the form fibre form for the faster passage of charge transportation. Although, the present form of GNFs from CR exists in more sp2 hybridized carbon domains in comparison to the GNFs from CF, which possesses lesser number of the sp2 hybridized carbon domains, which suggest that the GNFs from CR should have less disorderness in comparison to the GNFs from CF and this may be seen from 3D surface plot and hill view of the GNFs of GNFs from CR, where GNFs are arranged directionally and more orderly than the GNFs from CR. Further, connectivity of the GNFs was found to be maintained as the outer surface of GNFs from CR connected with each other with the outer surface of the graphene nanosheets.

Figure 11 illustrates FESEM images of GNFs from CR at high magnification in accordance with an embodiment of the present disclosure. Further, we have also investigated the cross-sectional surface morphology of randomly selected GNFs from CR at higher magnification i.e., at 1 µm and 400nm. Again, as found in the GNFs from CF, GNFs from CR also possessed several other GNFs at their surface with lower dimension GNFs made of graphene nanosheets. This kind of morphology probably arises due to shape selectivity of CR, where each CR thread maintains its configuration ever after the transformation into GNFs. Further, nano-dimensional porosity can be seen in the FESEM images of GNFs from CR at high magnification, which showed the high utility of the GNFs for the application of energy storage devices. Further, the images also depicted the possibility of efficient doping of the desired other nanomaterials for the tuning of properties of the present GNFs for various other applications because of availability of these nano-dimensional porosity with the GNFs. Figure 11 shows FESEM images of GNFs from CR at high magnification; and

Figure 12 illustrates UV-Visible spectra of the GNFs from CF in accordance with an embodiment of the present disclosure. Therefore, in order to analyse the possibility of the tuning of the properties of these GNFs, UV-visible spectroscopy was performed. Figure 12 shows UV-Visible spectra of the GNFs from CF. The UV-Visible spectra of the GNFs from CF showed a band at 265 nm corresponding to the p- p* transition, while the UV-visible spectra of the GNFs from CR showed a UV absorption peak at 262nm corresponding to the p - p * transition due to the presence of more sp2 hybridized carbon domains with the GNFs. Further another band at 310 nm was also seen due to n- p * transition. Moreover, the optical band gaps were also determined from the UV-visible spectra of GNFs from both CF and CR by plotting the Tauc plots.

According to Tauc’s approach the optical band gap the semiconductor materials can be find by using the following expression
(ah?)2 = A(h?-Eg) (1)
where, a is known as absorption coefficient and Eg is called band gap of the material. The optical band as calculated for the GNFs from CF was found to 2.21 eV, while in case of GNFs obtained from CR was found to be 1.57 eV. The band gap thus obtained showed that these GNFs could be used for photovoltaic applications. Especially the GNFs from CR could be used as active electrode materials for photovoltaic wires, as the present work also showed that these GNFs from CR make an effective flexible and conductive electrode, which somewhere also works like a conductive wire. In the present case, a flexible GNFs based conducting electrode with the length nearly 5 m was made, which showed the utility of the present work.

A scalable, eco-friendly and cost-effective synthesis process of GNFs from cotton sources (CF and CR) was demonstrated. The process consists two steps, where primary step relates to the hydrothermal treatment for the nucleation of carbon skeleton within the CF and CR, while the secondary step described pyrolysis treatment in the controlled environment of N2 gas. Micro Raman analysis showed the presence of sp2 clusters in both the GNFs of CF and CR respectively, where GNFs from CR possessed more sp2 clusters as depicted by the Raman analysis. Further the presence of sharp 2D bands and discernible D+G bands showed lesser disorder in both of the GNFs. FESEM images showed the presence of 2-5µm thick GNFs from both the cotton sources i.e., CF and CR. The 3D surface plot and hill view plot for both the GNFs depicted that GNFs from CF were randomly aligned, while GNF from CR were aligned in a particular direction (horizontal in the present case), therefore showed more ordered alignment of GNFs of CR. The UV-Visible spectrum of both the GNFs form cotton sources (CF and CR) showed reduced form of graphene nanosheets in both the GNFs and showed a broad spectrum with the presence of p- p* transition. The optical band gaps were calculated in order to understand the possibility of the applicability of these GNFs for energy harvesting applications. The GNFs from CF showed an optical band gap of Eg= 2.25 eV, while the GNFs from CR showed an optical band gap of Eg=1.59 eV. The obtained optical band gaps for both the GNFs perfectly suited for photovoltaic applications. Especially GNFs from CR showed the real time application for photovoltaic wire as the present form of GNFs from CR showed the fabrication of 5m long wire with the optimal band gap, which effectively suited as active electrode material for highly efficient photovoltaic wires. Thus, these GNFs form both the cotton sources have the potential to easily woven into various varieties of clothes and packages to serve as self-powered electric generators via conventional textile technology for a better future.

The process is profitable for electronic textile, polymer nanocomposites, graphene fiber actuators, graphene fiber motors, graphene fiber based photovoltaic wires, graphene fiber-based supercapacitors, graphene fiber-based adsorbents, graphene fiber based superconducting wires, graphene fiber-based mask to fight with deadly viruses, graphene fiber based portable Water filter, graphene fiber-based biosensor, and graphene fiber based electrical heaters.

The drawings and the forgoing description give examples of embodiments. Those skilled in the art will appreciate that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be split into multiple functional elements. Elements from one embodiment may be added to another embodiment. For example, orders of processes described herein may be changed and are not limited to the manner described herein. Moreover, the actions of any flow diagram need not be implemented in the order shown; nor do all of the acts necessarily need to be performed. Also, those acts that are not dependent on other acts may be performed in parallel with the other acts. The scope of embodiments is by no means limited by these specific examples. Numerous variations, whether explicitly given in the specification or not, such as differences in structure, dimension, and use of material, are possible. The scope of embodiments is at least as broad as given by the following claims.

Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments. However, the benefits, advantages, solutions to problems, and any component(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature or component of any or all the claims.

We Claims:

1. A process for manufacturing of graphene nanofibers (GNFs) from cotton sources, the process comprises:

soaking cotton fibre (CF) and cotton rope (CR) in ethyl alcohol and isopropyl alcohol to develop rapid carbon skeleton and flexibility within GNFs;
placing alcohol-soaked CF and CR inside a hydrothermal reactor at 150°C temperature for 5 hours for initiating nucleation of the carbon skeleton for growth of graphene nanosheets; and
performing high temperature pyrolysis for hydrothermally treated CF and CR inside tube furnace in the inert atmosphere of N2 gas at the temperature of 800°C with the heating rate of 5°C/min of 40 min for manufacturing of graphene nanofibers (GNFs).
2. The process as claimed in claim 1, wherein at temperature most of the carbon converts into the network of mixed form of the sp2 and sp3 hybridized carbon atoms, where the percentage of sp3 hybridized carbon atoms attained more value than the sp2 hybridized carbon atoms as mainly the possible carbon skeleton developed in this phase is belong to the formation of the graphene oxide.
3. The process as claimed in claim 1, wherein form of the graphene must be conductive for applications related to energy conversion and storage, which comes only when there is the high percentage of sp2 hybridized carbon atoms.
4. The process as claimed in claim 1, wherein high temperature pyrolysis process from 150°C to 800°C begins the development of graphitic nature with the skeleton of CF and CR.
5. The process as claimed in claim 1, wherein temperature of range 150°C to 800°C, bio-fuel also obtained as by product up to 400°C, while leaving behind carbon skeleton, which developed in graphitic form beyond this temperature.
6. The process as claimed in claim 1, wherein the scalable shape selectivity of the cotton-based materials are used to develop GNFs.