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Conversion of plastic waste into graphene nanosheets and its application in supercapacitor.

Herein, we report a robust approach for the selective covalent functionalization of graphene oxide (GO) with 4-hydroxybenzoic acid (HBA) for developing polymeric nanocomposites based on liquid crystalline polymers (LCPs). The functionalization of GO with HBA was confirmed by Raman spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, and X-ray diffraction (XRD) spectroscopy. The surface morphology of GO and functionalized GO (FGO) was studied using field emission scanning electron microscopy (FE-SEM). Furthermore, the interactions between FGO and LCPs have been investigated by FT-IR spectroscopy, whereas dispersion of GO and FGO in the LCP matrix was analyzed by FE-SEM. The better dispersion of FGO can be attributed to the hydrogen bonding and π-π stacking interactions between FGO and LCPs. Our results showed that even the addition of 5 wt% FGO in the LCP matrix significantly enhances the tensile strength and storage modulus of the pristine LCPs by 84% and 78% respectively. Compared to neat LCPs, FGO incorporated composites also demonstrate an improvement in the melting temperature (

This work reports a facile, eco-friendly, and cost-effective mass-scale synthesis of metal-doped graphene sheets (MDGs) using agriculture waste of Quercus ilex leaves for supercapacitor applications. A single step-degradation catalyst-based pyrolysis route was used for the manufacture of MDGs. Obtained MDGs were further evaluated via advanced spectroscopy and microscopic techniques including Raman spectroscopy, FT-IR, XRD, SEM/EDX, and TEM imaging. The Raman spectrum showed D and G bands at 1300 cm−1 and 1590 cm−1, respectively, followed by a 2D band at 2770 cm−1, which confirmed the synthesis of few-layered MDGs. The SEM/EDX data confirmed the presence of 6.15%, 3.17%, and 2.36% of potassium, calcium and magnesium in the obtained MDGs, respectively. Additionally, the FT-IR, XRD, TEM, and SEM data including the plot profile diagrams confirmed the synthesis of MDGs. Further, a computational study was performed for the structural validation of MDGs using Gaussian 09. The density functional theory (DFT) results showed a chemisorption/decoration pattern of doping for metal ions on the few-layered graphene nanosheets, rather than a substitutional pattern. Further, resulting MDGs were used as an active material for the fabrication of a supercapacitor electrode using the polymer gel of PVA–H3PO4 as the electrolyte. The fabricated device showed a decent specific capacitance of 18.2 F g−1 at a scan rate of 5 mV s−1 with a power density of 1000 W kg−1 at 5 A g−1.

Universal solid waste management and its hazardous effects on the ecology, ecosystem, and the global human health index are some of the major issues that are currently threatening our future. The overproduction of solid waste materials is mainly the consequence of human population explosion and extraordinary increase in global economy along with global productivity. Due to the rapid growth in global population and the related demands, the production of solid waste materials is increasing day by day. In order to have a better solution to solid waste management, the best ethical way is to convert solid waste materials into valuable carbon-based nanomaterials (CNMs) such as CNT, graphene, and carbon quantum dots (CQDs), which can further work as precursors in energy storage devices. This critical review summarizes the recent progress in the structural forms and current situational analysis of universal solid waste based CNMs. It also includes broadly discussed issues, starting with the current waste situation analysis of global energy crisis and the production of graphene, including its counterparts, as the precursors for supercapacitor applications. A paradigm study of various solid waste derived CNMs with their significance, which, in particular, depends upon the types of CNMs and the classification of solid waste derived CNMs on the basis of different types of pore size and pore distribution, has been carried out. The various structural modifications and their effects on the electrochemical properties have been discussed thoroughly for supercapacitor applications including their future possibilities and scope. The review outlines the crucial mechanism followed during the charge storage of different kinds of supercapacitors and various electrochemical calculations involved during the performance testing of the fabricated device. We hope that the target audience, belonging to the energy or material science field, may acquire relevant information from this review, which may further help them to design futuristic studies in the field.

This work reports an innovative approach to the fabrication of free-standing thin films of multiwalled carbon nanotubes (MWCNTs)/graphene oxide (GO) nanohybrids by using dimethyl formamide (DMF) and n-hexane as a solvent–antisolvent system for the growth of thin films of MWCNTs/GO nanohybrids. The synthesis of the GO was carried out by using the modified Hummers method, while the synthesis of MWCNTs/GO nanohybrids was done by the intermixing of the carboxylic acid functionalized MWCNT and GO using the solution-mixing method. The growth of the thin film of MWCNTs/GO nanohybrids was done by obeying the surface-tension-driven phenomena which occur mainly due to the coalescence of bubbles due to the solvent–antisolvent interfacial tension. Furthermore, density functional theory (DFT)-based first-principles simulations were performed to understand the structural, electronic, and capacitive aspects of MWCNT/GO nanohybrids. The computational results demonstrated excellent quantum capacitance in the MWCNT/GO nanohybrid electrodes. Inspired by the computational results, the same process elaborated above has also been employed to develop binder-free supercapacitor devices utilizing the MWCNT/GO nanohybrid as an electrode material. The electrochemical performance of this electrode in 1 M aqueous H2SO4 demonstrates a good energy density of 21.63 WhKg−1 at a current density of 0.5 Ag−1, with a high specific capacitance of 369.01 F/g at the scan rate of 2 mVs−1 and excellent cyclic stability of 97% for 5000 charge–discharge cycles.

We report the bulk phase synthesis of graphene sheets using waste plastic (WP) as a precursor following a modified pyrolysis approach. Furthermore, the low and high mass loading of vanadium pentaoxide was performed on graphene sheets in 1 : 10 and 1 : 1 ratios, respectively. Advanced characterization techniques such as Raman spectroscopy, FT-IR spectroscopy, X-ray diffraction (XRD) analysis, thermogravimetric analysis (TGA) analysis, and SEM imaging were used to confirm the synthesis of graphene. FT-IR spectroscopy confirmed that the resonating structure affects the bond strength in the composite, which enables peak shifting in the FT-IR spectrum of the composite. Furthermore, bandgap analysis has been performed using UV-Vis spectroscopy, which confirmed the synthesis of the composites. The developed vanadium-doped graphene was used as the active material for the fabrication of supercapacitor electrodes. The electrochemical performance of these devices was evaluated in 1 M H

The need of energy storage and related devices are increasing day by day, due to the expansion of global population. To deal with such universal crisis, current energy storage devices like supercapacitors need to be improved in their performances and qualities. In this regard, quantum dots (QDs) are extensively being studied, especially due to their excellent properties. The utilization of QDs in supercapacitors is huge as electrode material as well as for fluorescent electrolytes. Various QDs based composites have been made for the same, which includes doping with various metals, non-metals and carbon nanomaterials (CNMs) like graphene, carbon nanotubes (CNTs) etc. In the present chapter the current advancement and futuristic possibilities of supercapacitors have been mentioned extensively.

Herein, we report the first time application of waste plastic derived 3D graphene nanosheets (GNs) for hole transport material (HTM) free perovskite solar cells (PSCs), where 3D GNs have been employed as an electrode dopant material in monolithic carbon electrode based mesoscopic PSCs. Waste plastics were upcycled into high-quality 3D GNs by using two-step pyrolysis processes, where, a nickel (99.99%) metal mesh was taken as the catalytic and degradation template to get an acid free route for the synthesis of 3D GNs. Raman spectroscopy, HRTEM analysis and XRD analysis show the presence of 1–2 graphene layers within the 3D GNs. Further, the optical band gap study has also been performed to analyze the applicability of 3D GNs for PSCs. The optimized device with 3D GNs shows a power conversion efficiency (PCE) of 12.40%, whereas the carbon-based control device shows a PCE of 11.04%. Further, all other device parameters such as short circuit current (Jsc), open circuit voltage (Voc) and fill factor (FF) have been improved with the addition of 3D GNs. The performance enhancement in 3D GN doped HTM free PSC solar cells is attributed to the enhancement in conductivity and reduced recombination within the device. Further, the photocurrent study shows that the 3D GN device shows better performance as compared to the reference device due to the larger diffusion current. Thus, the upcycling of waste plastics into 3D GNs and their exploitation for application in energy conversion show an effective and potential way to convert waste into energy.

Herewith, we demonstrate a novel top-down approach for the cost-effective consecutive synthesis of 2D/3D graphene-based materials (GBM) from the extract and fibrous parts of the Drepanostachyum falcatum plant, using a two-stage thermal approach. At low temperature (150 °C), the extract of the D. falcatum showed the formation of a fluorescent 2D skeleton of the GBM i.e., metal-doped graphene oxide sheets (MDGOs) in presence of ethanol. On the other hand, the pyrolysis (∼300 °C) of the fibrous part showed the formation of a 3D skeleton of the graphene nanoribbons (GNR) in the N2 atmosphere. The presence of extensive π-π conjugated interactions with oxidative functional moieties in 2D-MDGOs is responsible for their blue fluorescent nature under UV irradiation at 365 nm. Meanwhile, 2D-MDGOs show excellent potential as a bio-imaging probe for non-tumorigenic prostate epithelial RWPE-1 cells. However, the very low cytotoxicity of 2D-MDGOs played a crucial role in upholding their bio-imaging potential. Simultaneously, the hydrophobic nature of 3D-GNR showed better adsorption towards the organic pollutants (dye) from the aqueous phase. The adsorption phenomenon of 3D-GNR was very fast and effective towards the removal of methylene blue (MB). Moreover, the Langmuir adsorption capacity for MB dye was found to be 31.94 mg/gm. This is the first time we are reporting the dual synthesis of 2D and 3D GBMs simultaneously, with different applicative potentials. Further, noticeable and in-depth observations were made for studying the reaction kinetics of the reaction to find a formal analytical connection between productivity, adsorptive, and applicability of 3D-GNR. Moreover, the market-based-cost analysis showed the huge industrial potential of these materials, which also make them inevitable and promising candidates for futuristic growth in their respective application in water purification.

Rubbers and plastics are the widely used polymeric materials for various kinds of applications such as automobiles, packaging, constructions, material handling, sports and toys etc. Because of long durability and ease of manufacturing rubbers and plastics are vigorously used in last decades. However, long term durability of these materials becomes a serious issue for the environment and treated as hazardous waste polymeric materials at the end of their life. Still these polymeric materials, showed the extensive critical problems due to unfruitful management. Among these, rubber waste is exponentially increase in past few year because of revolutionary changes in automobile industry and dependency of human over the automobile. To overcome this issue, land filling and combustion are the most employed traditional methods used for the disposing and treatment of rubber waste, respectively. Although, these methods showed several disadvantages such as evolution of toxic gases, dust, fumes and water pollution etc. Hence, the whole world is looking out for some of the best promising solutions to utilize these polymeric waste materials into value added products. In this regard, recycling and upcycling of rubber waste into value added products such as thermoplastic elastomers (TPE), value added fuels, additive materials for construction and carbon nanomaterials. Upcycling of waste rubbers into TPE showed one of the methods to get the value added products, however the incompatibility and immiscibility of the rubber based additives in polymer matrix show poor mechanical performance. On the other hand, upcycling of waste rubbers into value added fuels and carbon nanomaterials showed a potential remediation process for a wealthy management of rubber waste, while another way of recycling use of rubber waste in construction materials. Although whatever be recycling and upcycling process were suggested by various researchers, still a deep insight is urgently needed in order to confront the upcoming challenges of the rubber waste. Thus, the present chapter describes the detailed recycling and upcycling processes, challenges and future recommendations regarding the management of the rubber waste.

Plastics are the polymers of their respective constituting monomer units and they are emerging as essential materials in day to day life. Due to the extensive use of plastics, they generate a large trajectory of plastics waste around us which are creating huge environmental pollution. On the other hand, energy is also an important aspect of human society without energy life is unimaginable. The modern lifestyle of human and heavily dependably over the electrical appliances need more alternative and green energy resources. For this, energy storage devices especially supercapacitor emerges as the green and alternative energy source which have the capability to fulfill the world energy demand and will also reduce the dependency over fossil fuels. In addition, carbon nanomaterials such as graphene, carbon nanotubes and other nanostructures evolved as the miracle materials due to their attractive properties and many folds application in different areas. Thus, here, in this chapter, we will discuss the three dimensional approaches for removal of plastics footprints from our environments. In this regard, a three dimensional approach have been discussed which includes waste plastics conversion techniques with their advantages and disadvantages, conversion of waste plastics into carbon nanomaterials and their potential applications in supercapacitor.

This article reports a sustainable, and greener production of graphene sheets from waste plastics, further their utilization into the enhancement of compression and tensile strength of cementing concrete mixture. A modified binary pyrolysis approach was followed for the production of graphene sheets from waste plastic. Further, the potential of synthesized graphene sheets was tested for making the high-standard concrete. In this regard, four concrete mixtures having different ratios of waste plastic derived graphene sheets (WGS) (0.10%, 0.5%, 1.0%, and 1.5%) along with pure concrete blocks were prepared. The results exhibited the comprehensive enhancement of 42.86% in compression strength and 30% in tensile strength for the sample with 0.5% of WGS which was cured for 28 days. Further, the market cost analysis of designed concrete mixtures was done from the economical index point of view. Also, evaluations of the mechanical strength data suggested, that the WGS based concrete blocks (WGB) namely WGB-01 and WGB-02 showed greater performance with affordable cost.

2D carbon nanomaterials such as graphene and its oxide counterpart have sought good research attention for their application as well as fundamental interest. Especially the versatility of graphene oxide establishes its elite candidature in every field because of diverse application potential. Here we are reporting a greener, eco-friendly and cost effective one step hydrothermal route for the synthesis of potassium doped graphene oxide (K-doped GO) from agricultural waste i.e. Quercus ilex Fruit. The elemental analysis and XPS study showed the high percentage (6.81%) of natural doping of potassium. The K-doped GO is specific and demonstrates bright blue photoluminescence (PL) under UV-light (λex = 365 nm). Low toxicity, intracellular localization, good biocompatibility and strong PL properties of the synthesized K-doped GOs portray it as an excellent bio-imaging agent holding great promise in analytical and biological fields.