Highly ordered hierarchical porous carbon derived from biomass waste mangosteen peel as superior cathode material for high performance supercapacitor

Carbon-based brilliance: a novel approach to renewable energy in radiotherapy centers

The energy produced from other sources which does neither come from fossil fuels nor contribute in the production of any greenhouse effects that causes climate changes is called as 'Alternative Energy'. Since our world's primary energy sources such as coal, oil and natural gases are exploited to a greater extent, we are in an urge to switch to an alternative energy. Scattered radiation, a common byproduct in radiation therapy and diagnostic radiology, presents a unique opportunity in the realm of alternative energy. As a potential source of interference, scattered radiation can be repurposed to contribute to sustainable energy solutions. Addressing the issue of scattered radiation wastage and utilizing it for alternative energy, an activated carbon-based solar cell emerges as a solution. This solar cell, a conventional one in which cadmium Telluride is replaced by coconut shell based carbon material, has the potential in producing a significant amount of electrical energy by utilizing scattered radiation from radiotherapy and radiology machines. Furthermore, this activated carbon based-material undergoes thorough characterization into various teletherapy and radiology machines, and it can be seamlessly integrated into clinical practices.

Upcycling of surgical facemasks into carbon based thin film electrode for supercapacitor technology

Polypropylene (PP), a commonly used plastic, is used for making the outer layers of a surgical face mask. In 2020, around 3 billion surgical face masks were disposed into the environment, causing a huge threat to wildlife, aquatic life, and ecosystems. In this work, we have reported the sulfonation technique for stabilizing the surgical face masks and their conversion into carbon nanoparticles for application as a supercapacitor electrode. The electrode is fabricated by preparing a slurry paste of carbon nanoparticles and pasting it on a conductive wearable fabric. To investigate the performance of the carbon thin film electrode, electrochemical techniques are employed. The Cyclic Voltammetry (CV) analysis performed at different scan rates in a 6 molar KOH electrolyte reveals that the carbon thin film acts as a positive electrode. At 4 A g^-1, the electrode shows a specific capacitance of 366.22 F g^-1 and 100% retention of specific capacitance for 8000 cycles. A two-electrode asymmetric device is fabricated using carbon thin film as the positive electrode, NiO thin film as the negative electrode, and a KOH separator between two electrodes. The device shows a specific capacitance of 113.73 F g^-1 at 1.3 A g^-1 and glows a red LED for 6 min. This work is a step towards upcycling the waste produced from surgical face masks used during the COVID-19 pandemic and its application for energy storage.

Homogeneous activation induced by bacterial cellulose nanofibers to construct interconnected microporous carbons for enhanced capacitive storage

Porous carbons have been widely applied for capacitive energy storage, yet usually suffer from insufficient rate performance because of the sluggish ion transport kinetics in deep and multi-branched pores. Herein, we fabricated an interconnected microporous capacitive carbon (IMCC) by growing D (+)-glucosamine on bacterial cellulose (BC) nanofibers scaffold, followed by carbonization and activation. The BC nanofibers acted as a sacrificial template during pre-carbonization, facilitating the subsequent KOH permeation and homogeneous activation. By taking advantage of the interconnected microporous structure, the IMCC delivers a high capacitance of 302 F g^-1 at 1 A g^-1 and an excellent rate capability of 165 F g^-1 at 100 A g^-1 for aqueous supercapacitor, demonstrating its fast ion transport capability. Impressively, it also shows a superior gravimetric capacity of 177 mAh g^-1 at 0.5 A g^-1 and remains a high value of 72 mAh g^-1 at 20 A g^-1 as a cathode material for Zn-ion hybrid capacitor. This facile and cost-effective design strategy exhibits a great potential to construct carbohydrates-derived interconnected microporous carbon materials for high-rate energy storage.

Facile Synthesis of Biocarbon-Based MoS2 Composite for High-Performance Supercapacitor Application

Nanocomposites are gaining high demand for the development of next-generation energy storage devices because of their eco-friendly and cost-effective natures. However, their short-term energy retainability and marginal stability are regarded as hindrances to overcome. In this work, we demonstrate a high-performance supercapacitor fabricated by biocarbon-based MoS₂ (Bio-C/MoS₂) nanoparticles synthesized by a facile hydrothermal approach using date fruits. Here, we report the high specific capacitance for a carbon-based nanocomposite employing the pyrolysis technique of converting agricultural biowaste into a highly affordable energy resource. The biocompatible Bio-C/MoS₂ nanospheres exhibited a high capacitance of 945 F g^-1 at a current density of 0.5 A g^-1 and an excellent reproducing stability of 92% after 10000 charge/discharge cycles. In addition, the Bio-C/MoS₂ NS showed an exceptional power density of 3800-8000 W kg^-1 and an energy density of 74.9-157 Wh kg^-1. The results would pave a new strategy for design of eco-friendly materials toward the high-performance energy storage technology.

Hierarchical porous carbon foam electrodes fabricated from waste polyurethane elastomer template for electric double-layer capacitors

Plastic waste has become a major global environmental concern. The utilization of solid waste-derived porous carbon for energy storage has received widespread attention in recent times. Herein, we report the comparison of electrochemical performance of porous carbon foams (CFs) produced from waste polyurethane (PU) elastomer templates via two different activation pathways. Electric double-layer capacitors (EDLCs) fabricated from the carbon foam exhibited a gravimetric capacitance of 74.4 F/g at 0.1 A/g. High packing density due to the presence of carbon spheres in the hierarchical structure offered excellent volumetric capacitance of 134.7 F/cm³ at 0.1 A/g. Besides, the CF-based EDLCs exhibited Coulombic efficiency close to 100% and showed stable cyclic performance for 5000 charge-discharge cycles with good capacitance retention of 97.7% at 3 A/g. Low equivalent series resistance (1.05 Ω) and charge transfer resistance (0.23 Ω) due to the extensive presence of hydroxyl functional groups contributed to attaining high power (48.89 kW/kg). Based on the preferred properties such as high specific surface area, hierarchical pore structure, surface functionalities, low metallic impurities, high conductivity and desirable capacitive behaviour, the CF prepared from waste PU elastomers have shown potential to be adopted as electrodes in EDLCs.

Couple of Nonpolarized/Polarized Electrodes Building a New Universal Electrochemical Energy Storage System with an Impressive Energy Density

Herein, we propose a new concept of energy storage system composed of a nonpolarized electrode and a polarized electrode (PPE) with an impressive energy density. It offered nearly 4 times higher energy density than that of carbon-based supercapacitor. Among the suggested potential PPE system, we introduced an electrodeposited nanozinc on the copper foam as the nearly nonpolarized electrode and a Zn-2,5-dihydroxyterephthalic acid (DHTA) metal-organic framework (MOF)-derived activated porous carbon as a nearly polarized electrode in KOH-ZnO electrolyte to constitute the C|Zn PPE system prototype. The C|Zn system achieved an impressive energy density of 84.5 Wh kg^-1 at 1000 W kg^-1, 4 times higher than that of the C|C supercapacitor. It also shows a high capacitance retention rate of 94.5% at 10 A g^-1 after 10 000 cycles. Therefore, the amazing results indicate that the PPE energy system integrates the advantages of supercapacitors and secondary batteries. It will be a promising and effective energy device for higher-performance electric vehicles.

Meso/Microporous Carbons from Conjugated Hyper-Crosslinked Polymers Based on Tetraphenylethene for High-Performance CO2 Capture and Supercapacitor

In this study, we successfully synthesized two types of meso/microporous carbon materials through the carbonization and potassium hydroxide (KOH) activation for two different kinds of hyper-crosslinked polymers of TPE-CPOP1 and TPE-CPOP2, which were synthesized by using Friedel–Crafts reaction of tetraphenylethene (TPE) monomer with or without cyanuric chloride in the presence of AlCl₃ as a catalyst. The resultant porous carbon materials exhibited the high specific area (up to 1100 m² g⁻¹), total pore volume, good thermal stability, and amorphous character based on thermogravimetric (TGA), N₂ adsoprtion/desorption, and powder X-ray diffraction (PXRD) analyses. The as-prepared TPE-CPOP1 after thermal treatment at 800 °C (TPE-CPOP1-800) displayed excellent CO₂ uptake performance (1.74 mmol g⁻¹ at 298 K and 3.19 mmol g⁻¹ at 273 K). Furthermore, this material possesses a high specific capacitance of 453 F g⁻¹ at 5 mV s⁻¹ comparable to others porous carbon materials with excellent columbic efficiencies for 10,000 cycle at 20 A g⁻¹.

Electrochemical energy storage electrodes from fruit biochar

This review investigates the electrochemical energy storage electrode (EESE) as the most important part of the electrochemical energy storage devices (EES) prepared from fruit-derived carbon. The EES devices include batteries, supercapacitors, and hybrid devices that have various regular and advanced applications. The preparation of EESE from fruit wastes not only reduce the price of the electrode but also lead to enhance the electrochemical properties of the electrode. The astonishing results of fruits biochar at electrochemical analyses guarantee the performance of these electrodes as EESE. Also, using fruit waste as the precursor of the EESE due to protect the environment and reduce environmental pollutions.

Hierarchical porous carbon derived from jujube fruits as sustainable and ultrahigh capacitance material for advanced supercapacitors

Herein, we propose a new highly porous natural carbon material from renewable and inexpensive jujube fruits as a carbon source applied in supercapacitors. The combination of pre-carbonization and chemical activation approaches is employed to product hierarchical porous carbon from natural jujube fruits. The specific surface area of the prepared porous carbon is increased from 85.4 to 1135 m² g^-1 after the completion of NaOH activation at an optimized condition, which is beneficial to enhancing electrochemical performance of supercapacitors. A 3-electrode configuration was utilized to explore the electrochemical ability of porous carbon in 6 M KOH electrolyte. The acquired results demonstrate that porous carbon displays the specific capacitance of 587, 460 and 324 F g^-1 at 0.1, 1 and 100 A g^-1, respectively, which is confirmed by its admirable capacitance and rate behaviors. The porous carbon also shows a wonderful durability with a capacitance retention of 92.2% after 130,000 cycles at 50 A g^-1. Moreover, the assembled symmetrical coin-like supercapacitors with wide potential window of 2.5 V in 1 M Et₄NBF₄/AN organic electrolyte offer a high energy density of 23.7 Wh kg^-1 at 0.629 kW kg^-1 with remaining 94% capacitance over 10,000 cycles at 30 A g^-1, indicating its practical application prospect. As a result, the present study proves the natural jujube fruits is a promising sustainable carbon source for making more economical and efficient electrode material of high performance supercapacitors.