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

Presently, carbon-based nanomaterials have shown tremendous potential for energy conversion applications. Especially, carbon-based materials have emerged as excellent candidates for the fabrication of halide perovskite-based solar cells, which may lead to their commercialization. In the last decade, PSCs have rapidly developed, and these hybrid devices demonstrate a comparable performance to silicon-based solar cells in terms of power conversion efficiency (PCE). However, PSCs lag behind silicon-based solar cells due to their poor stability and durability. Generally, noble metals such gold and silver are employed as back electrode materials during the fabrication of PSCs. However, the use of these expensive rare metals is associated with some issues, urgently necessitating the search for cost-effective materials, which can realize the commercial applications of PSCs due to their interesting properties. Thus, the present review shows how carbon-based materials can become the main candidates for the development of highly efficient and stable PSCs. Carbon-based materials such as carbon black, graphite, graphene nanosheets (2D/3D), carbon nanotubes (CNTs), carbon dots, graphene quantum dots (GQDs) and carbon nanosheets show potential for the laboratory and large-scale fabrication of solar cells and modules. Carbon-based PSCs can achieve efficient and long-term stability for both rigid and flexible substrates because of their high conductivity and excellent hydrophobicity, thus showing good results in comparison to metal electrode-based PSCs. Thus, the present review also demonstrates and discusses the latest state-of-the-art and recent advances for carbon-based PSCs. Furthermore, we present perspectives on the cost-effective synthesis of carbon-based materials for the broader view of the future sustainability of carbon-based PSCs. Validerad;2023;Nivå 2;2023-03-22 (hanlid);Funder: NMHS; GBPHIED (GBPNI/NMHS-2019-20/MG) Kosi-Katarmal, Almora, India; National Research Foundation of Korea (NRF) - Ministry of Education (2022R1F1A1073950)

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

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.