Mesoporous graphitic carbon electrodes derived from boat-fruited shells of Sterculia Foetida for symmetric supercapacitors for energy storage applications

In recent years, intensive research efforts have focused on translating biomass waste into value-added carbon materials broadcasted for their significant role in energy and environmental applications. For the first time, high-performance carbonaceous materials for energy storage applications were developed from the multi-void structure of the boat-fruited shells of Sterculia Foetida (SF). In that view, synthesized mesoporous graphitic activated carbon (g-AC) via the combination of carbonization at various elevating temperatures of 700, 800, and 900 °C, respectively, and alkali activation by KOH, with a high specific surface area of 1040.5 m2 g-1 and a mesopore volume of 0.295 cm3 g-1. In a three-electrode configuration, the improved electrode (SF-K900) exhibited excellent electrochemical behavior, which was observed in an aqueous electrolyte (1 M H2SO4) with a high specific capacitance of 308.6 F/g at a current density of 1 A/g, owing to the interconnected mesopore structures and high surface area of SF-K900. The symmetric supercapacitor (SSC) delivered the specific capacitance of 138 F/g at 1 A/g with a high energy density (ED) of 13.4 Wh/kg at the power density (PD) of 24.12 kW/kg with remarkable cycle stability and supercapacitive retention of 93% over 5000 cycles. Based on the findings, it is possible to develop low-cost active electrode materials for high-rate performance SSC using mesoporous g-AC derived from SF boat-fruited shells.

Synthesis of Activated Porous Carbon from Red Dragon Fruit Peel Waste for Highly Active Catalytic Reduction in Toxic Organic Dyes

In this study, an alternative precursor for production of biomass-derived activated carbon was introduced using dragon fruit (Hylocereus costaricensis) peels. Chemical activators such as FeCl3, MgCl2, ZnCl2 were used in the thermal carbonization process to convert carbon into porous carbon (PC). However, heteroatom-doped PC catalysts including N-, B-, and P-doped carbon catalysts in the field of dye removal is highly desirable. Several approaches (XRD, FE-SEM/TEM, XPS, FT-IR, EDS, and elemental mapping) were employed to examine the surface morphology, surface properties, and elemental composition of the PC catalyst. The catalytic activity of metal-free PC catalyst was demonstrated for methylene blue (MB), crystal violet (CV), and Nile blue (NB) in a mild environment The corresponding rate constant (kapp) values were estimated as 0.2473, 0.3248, and 0.3056 min−1, respectively, for MB, CV, and NB, which were significantly greater than those of numerous reports. It exhibited the best catalytic activity and recyclability. Moreover, the approach proposed here could create new opportunities for the remediation of organic dyes in lakes and industrial wastewater.

White light-emitting, biocompatible, water-soluble metallic magnesium nanoclusters for bioimaging applications

Ultra-small (1.6 nm), water-soluble, white light-emitting (WLE), highly stable (∼8 months) BSA templated metallic (Mg⁰) nanoclusters (fluorescent magnesium nanoclusters = FMNCs) is developed using the green and facile route. Synthesis was facilitated by the reduction of magnesium salt, where template bovine serum albumin is utilized as a reducing agent and ascorbic acid act as a capping agent to impart stability in water, thereby obtaining stabilized Mg⁰nanoclusters In solution, stabilized Mg⁰nanoclusters produce white light (450-620 nm with FWHM ∼120 nm) upon 366 nm light excitation. This white light emission was found to have a CIE coordinate of 0.30, 0.33 [pure white light CIE (0.33, 0.33)]. Taking advantage of WLE and ultrasmall size, FMNCs were used forin vitrofluorescence imaging of HaCaT cell lines, yielding blue (τ= 2.94 ns, with a relative of QY = 1.2 % w.r.t QS), green (τ= 3.07 ns; relative quantum yield of 4.6% w.r.t R6G) and red (τ= 0.3 ns) images. Further, incubation of FMNCs with HEK293 (Human embryonic kidney cell) and cancerous MDA-MB-231 (Breast cancer cell line) human cell lines yielded 100 % cell viability. Current work is envisioned to contribute significantly in the area of science, engineering, and nanomedicine.

Superior thermal-charging supercapacitors with bio-inspired electrodes of ultra-high surface areas

High-performance thermally chargeable supercapacitors (TCS) greatly depend on the design of electrode materials. The unique features of succulents of absorbing water for sustaining their lives during long severe droughts imply that there exist vast spaces inside these plants, which inspires us of fabricating biomass-based electrodes by means of such succulents to develop highly efficient TCS. The optimized porous carbon prepared from succulents presents a high specific surface area of up to 3188 m² g⁻¹, resulting in the superior capability of accommodating a vast amount of ions and promising thermal charging performance. The TCS with this carbon electrode can generate an open-circuit voltage of 565 mV under a temperature difference of 50°C with a temperature coefficient as high as 11.1 mV K⁻¹. This article provides a new method for the preparation of porous carbon from biomass for the TCS system.

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Graded porous carbon is prepared from succulents as initial raw materials.

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The porous carbon presents a high specific surface area of up to 3188 m² g⁻¹.

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The NMR is utilized to characterize the superior ability of accommodating Li+.

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The system with the porous carbon can generate a voltage of 565 mV at ΔT = 50 °C.

Mesoporous onion-like carbon nanostructures from natural oil for high-performance supercapacitor and electrochemical sensing applications: Insights into the post-synthesis sonochemical treatment on the electrochemical performance

Although onion-like carbon nanostructures (OLCs) are attractive materials for energy storage, their commercialization is hampered by the absence of a simple, cost-effective, large-scale synthesis route and binder-free electrode processing. The present study employs a scalable and straightforward technique to fabricate sonochemically tailored OLCs-based high-performance supercapacitor electrode material. An enhanced supercapacitive performance was demonstrated by the OLCs when sonicated in DMF at 60 °C for 15 min, with a specific capacitance of 647 F/g, capacitance retention of 97% for 5000 cycles, and a charge transfer resistance of 3 Ω. Furthermore, the OLCs were employed in the electrochemical quantification of methylene blue, a potential COVID-19 drug. The sensor demonstrated excellent analytical characteristics, including a linear range of 100 pM to 1000 pM, an ultralow sensitivity of 64.23 pM, and a high selectivity. When used to identify and quantify methylene blue in its pharmaceutical formulation, the sensor demonstrated excellent reproducibility, high stability, and satisfactory recovery.

3D silk fibroin/carbon nanotube array composite matrix for flexible solid-state supercapacitors

Silk fibroin decorates CNTA to form 3D microporous N-doped carbon frameworks for high-performance supercapacitors with high flexibility and wettability.

Zwitterionic Polymer Modified Porous Carbon for High-Performance and Antifouling Capacitive Desalination

Capacitive deionization (CDI) is an emerging technology for effective brackish water desalination to address fresh water scarcity. It is of great interest due to its high energy efficiency, environmental friendliness, and low-cost operation compared with traditional desalination technologies. However, electrode fouling, caused by dissolved organic matter and resulting in reduction of electrode electrosorption capacity and device lifespan, is an impediment to practical application of CDI. Herein, we report a novel salty water desalination electrode with excellent antifouling properties. The antifouling electrode is prepared by coating zwitterionic polymer brushes, i.e., poly(sulfobetaine methacrylate) (SBMA), on porous carbon (PC) via surface-initiated atom transfer radical polymerization. The successful coating of zwitterionic polymer on PC surface is confirmed by transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, and other characterizations. Coating with polySBMA did not affect the electrosorption capacity of PC electrodes and imparted antifouling properties (versus fouling by model foulant bovine serum albumin) during long-term salt removal tests (100 desalination/regeneration cycles). This is an important step toward practical application of capacitive deionization technology for brackish water desalination.

Fabrication of Hierarchical Porous Carbon Nanoflakes for High-Performance Supercapacitors

In the current work, the carbon nanoflakes (CNs-Fe/KOH) and porous carbon (PC-Ni/KOH) have been produced by using Fe(NO₃)₃/KOH and Ni(NO₃)₂/KOH as the cographitization/activation catalysts to treat the natural plane tree fluff, respectively. The as-prepared carbon materials show different morphologies when treated with different metal ions. Compared with PC-Ni/KOH, the CNs-Fe/KOH have both high graphitization degree (I_G/I_D = 1.53) and large S_BET (1416 m²/g). In a three-electrode setup, the CNs-Fe/KOH electrode shows a high specific capacitance of 253 F/g at 10 A/g, with a capacitance retention of 92.64% after 10000 cycles in 2 M H₂SO₄ aqueous solution, which is far better than the sample without Fe³⁺ addition. In 1 M LiPF₆ in ethylene carbonate/diethyl carbonate organic solution, CNs-Fe/KOH-based symmetric supercapacitor also presents an excellent specific capacitance of 32.2 F/g at 1 A/g. In addition, an energy density of 39.98 W h/kg can be achieved at the power density of 1.49 kW/kg. Influence of metal ions on the morphology and structure as well as electrochemical performance of the carbon materials are further analyzed in detail. The current work provides a novel path for design and fabrication of supercapacitor electrode materials with promising electrochemical performances.

Energy storage applications of biomass-derived carbon materials: batteries and supercapacitors

Recent advances in the application of biomass-derived carbon materials in batteries and supercapacitors.

Facile synthesis and supercapacitor performances of nitrogen doped CNTs grown over mesoporous Fe/SBA-15 catalyst

Herein, we report a new strategy to synthesize high-yield nitrogen-doped carbon nanotubes (NCNTs) using iron-supported SBA-15 as a catalystviathe chemical vapour deposition (CVD) method to utilize them as an electrode material for supercapacitors.

Preparation of N, P co-doped activated carbons derived from honeycomb as an electrode material for supercapacitors

Preparation of N, P co-doped activated carbon derived from the honeycomb as an electrode material for supercapacitors.