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Due to the immense demand for flexible supercapacitors, it is important to develop low-cost and smarter solutions. To date, supercapacitors made of eco-friendly materials have been either expensive or of limited use. Herein, we report a solid-state, lightweight, low-cost, and plant-based supercapacitor for applications in flexible electronics. The asymmetric supercapacitor is made of MnO 2 deposited on activated carbon and lignin as a substrate using hydrothermal deposition. With Al/AC/lig-MnO 2 anode and Al/AC cathode, the supercapacitor is assembled using a poly(vinyl alcohol) (PVA)/H 3 PO 4 gel electrolyte. Morphological characterization is conducted using microtomography and scanning electron microscope. Electrochemical performance is assessed using cyclic charge−discharge, cyclic voltammetry, and electrochemical impedance spectroscopy. A series of compositions of AC:lignin:MnO 2 are optimized for best performance. After 2000 cycles, the specific capacitance obtained at 6.01 mA g −1 is 5.52 mF cm −2 , which is up to 13 times reported. Retention is 98.7% after 1000 cycles and 97.5% after 2000 cycles. The maximum energy density, power density, and Coulombic efficiency obtained are 14.11 Wh kg −1 , 1 kW kg −1 , and 98%, respectively. The favorable electrochemical performance makes it useful for a wide variety of electronics. This new approach to fabricate electrodes from green sources, with constituent optimization and cost-effectiveness, marks an important step toward green energy technology development.

An effective yet simple approach was developed to synthesize mesoporous PdBi nanocages for electrochemical applications. This technique relies on the subtle utilization of the hydrolysis of a metal salt to...

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Ultrafast formation of stable and self-assembled rhenium (Re) nanoparticles (NPs) using a poly allylamine hydrochloride (PAH) scaffold within 120 s of wet-chemical reaction at room temperature in aqueous solution has been reported. The average diameters of the two different sets of Re NPs synthesized are ∼0.7 ± 0.25 and ∼1.7 ± 0.3 nm, which can be easily achieved by controlling the polymer to Re7+ molar ratio. The small-size Re NPs are formed in solution, self-assembled together to form the chain-like or necklace-like structure. The synthesized Re NPs were used in two different potential applications, such as in catalysis and in surface-enhanced Raman scattering (SERS) studies. Catalysis study was done for 4-nitroaniline (4-NA) reduction with excess NaBH4 taking two different sets of Re NPs as catalyst. The highest catalytic rate for nitroaromatics reduction ever reported of ∼1.52 × 10–1 min–1 has been observed with large-size Re NPs as catalyst. In SERS, methylene blue (MB) was used as a Raman probe molecule. Strong SERS enhancements were observed with both sets of Re NPs due to their ultrasmall size, narrow interparticle gap, and self-assembled structure in PAH scaffold. These closely tethered and self-assembled Re NPs generated more surface active “hot spots” that resulted in good SERS enhancement. The present synthesis route is easy, cost effective, and fast and can generate stable Re NPs which could further be applied in interdisciplinary fields other than catalysis and SERS in the near future.

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