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As a cathode in aqueous zinc-ion capacitors (ZICs), nitrogen-doped carbon with a 2D bimetallic chalcogenide (NbMo6S8/NC) was used. The assembled ZIC demonstrated exceptional electrochemical stability and energy efficiency over thousands of charge–discharge cycles.

We developed a flexible supercapacitor cell with biocompatible oxidized SWCNTs driven by electrolytes in body fluids through integration with a wireless sensor network for use in implantable electronic medical devices (IEMDs).

Human curiosity about the mysteries in outer space has driven humans to organize space explorations. Space missions and polar region solicitations require the use of new energy storage technologies with excellent tolerance to extremely low temperatures and the capability to operate efficiently for an extended time. In this context, it is urgent to explore new approaches and concepts to address the critical challenges via mechanistic understanding of new electrochemical reactions and phenomena in diverse scenarios. This paper presents how electrode and electrolyte materials in supercapacitor (SC) cells operate at extremely low temperatures. The critical challenges related to engineering such SCs and the major breakthroughs that overcome these problems are presented. In addition, the effects of different electrolytes (e.g., aqueous, organic, and ionic liquids (ILs)) on the ion accessibility, interfacial charge transfer, and transport kinetics in SC cells under cold conditions are discussed. This review is expected to contribute to the development of high-performance SC cells that can function at severe temperatures by providing insight into the key challenges and guidelines that facilitate future work.

Due to their high capacity, nickel–cobalt-based cathode materials have attracted significant attention as potential components of hybrid solid-state supercapacitors (HSSCs). However, their poor cycling stability and low rate capability have impeded their implementation. In the present study, a single-step, binder-free potentiodynamic polarization approach is presented for the preparation of battery-type phosphorus-containing amorphous trimetal nickel–ruthenium–cobalt hydroxide (P@NRC-OH) nanofibers on Ni foam for use in high-energy, stable HSSCs. The phosphate dopant and the trimetal-rich electrode surface increase the intrinsic electron conductivity and redox activity and generate a large number of active defects. As a consequence, a P@NRC-OH electrode exhibited enhanced energy storage properties in terms of specific capacity (541.66 mA h g−1 at 3 mA cm−2), cycling durability (90.35% over 20 000 cycles), and rate capability (308.64 mA h g−1 at 20 mA cm−2). An assembled full-cell HSSC with P@NRC-OH nanofibers as the cathode material and porous activated carbon as the anode material produced a maximum specific energy of 90.02 W h kg−1 at a specific power of 1363 W kg−1 which remained as high as 37.87 W h kg−1 at a power density of 6818.18 W kg−1, with remarkable cycling stability over 15 000 charge–discharge cycles. The proposed approach thus represents a scalable and efficient strategy for the design of electrodes and devices with superior electrochemical performance.

In this work, a unique one-pot green synthesis technique that utilizes high energy gamma-irradiation technology was successfully designed to fabricate a stable, highly-porous Prussian blue (PB)/polyvinylpyrrolidone (PVP)/reduced graphene oxide (rGO) aerogel (PB@PVP/rGO) with a 3D-network structure, low density, and high mechanical strength. In this synthesis process, PB nanoparticles were generated in situ and then homogenously distributed and entrapped within the PVP/rGO aerogel. The synthesized aerogel exhibited (i) a three-dimensional microporous architecture consisting of an interconnected network structure with an ultra-low density of 0.0273 g cm−3; (ii) remarkable swelling ability in the presence of water at low pH levels; and (iii) strong mechanical stability, leading to excellent deformability without cracks or the loss of structural integrity, due to the double-network structure of the PB@PVP/rGO aerogel and the crosslinking between the stiff GO sheets and the flexible PVP chains. The hydrophilic PB@PVP/rGO aerogel demonstrated the rapid adsorption of Cs+ ions and MB dye due to capillary action; based on the Langmuir model it demonstrated a maximum adsorption capacity of 143.88 and 44.73 mg g−1 for Cs+ and MB, respectively. The PB@PVP/rGO aerogel also exhibited outstanding oil absorption capacity, which we attribute to its highly interconnected porous structure and the presence of oleophilic rGO. The excellent adsorption properties coupling with the unique structural features of this PB@PVP/rGO aerogel make it a promising adsorbent for oil spills and for the removal of environmental pollutants such as Cs+ and MB in water.

The demand for battery-type materials having hierarchical architectures, large surface areas, and excellent redox properties, to develop high energy density asymmetric supercapacitors (ASCs), is increasing. Herein, a facile single-step wet chemical method is proposed, which allows an engineered combination of α-NiMoO4 hierarchical heterostructures to be used as advanced battery-type electrodes for ASCs. The as-synthesized architectures consist of versatile nanogeometries including nanowires, nanosheets, and nanoparticles in the form of Rhynchostylis retusa-like heterostructures, which synergistically enhance the energy storage properties; specifically, at a current density of 2 A g−1, heterostructured α-NiMoO4 exhibits a superior specific capacitance of 1061 F g−1 and an outstanding cycling stability of 96%. Moreover, an aqueous ASC is fabricated by combining such a redox-type α-NiMoO4 heterostructure and activated porous carbon as the positive and negative electrodes, respectively, separated with a piece of filter paper. This device shows high energy and power densities (31.8 W h kg−1 and 786.5 W kg−1, respectively), which are useful to operate various portable electronic appliances. Together with the excellent cycling stability and energy storage properties, the synthesized heterostructured metal molybdates exemplify a new approach to develop novel electrode materials for high-performance aqueous ASCs.

Recently, organic–inorganic hybrid structures have gained significant interest and are considered as an innovative alternative for the development of multifunctional materials. Herein, we report highly reliable and reproducible protein–inorganic hybrid CaMoO4:Eu3+ microstructures as a novel photocatalyst for decontamination of environments using an energy-efficient and cost-effective green synthesis. In this synthesis process, streptavidin (SA) serves as an organic scaffold and builds covalent bonds with the amine groups of the CaMoO4:Eu3+ surface, which leads to the formation of membrane-bound-like structures. Because of the well overlapped absorption bands of tyrosine residues and CaMoO4:Eu3+, SA acts as a sensitizer and transfers more UV energy to the MoO4 moieties of CaMoO4:Eu3+, resulting in an enhanced emission intensity along with a blue shifted absorption spectrum. Compared to the commercial TiO2, the CaMoO4:Eu3+ host and SA modified CaMoO4:Eu3+ microstructures exhibit 145 and 207% higher dye removal efficiencies for methylene blue, signifying their light absorption efficiency and higher number of surface-active sites. After hybridization with SA, the CaMoO4:Eu3+ sample offers more photo-generated electrons to improve the photocatalytic activity along with an enhanced photocurrent density of 0.72 μA cm−2, which is about 1.5 times higher than that of the CaMoO4:Eu3+ host. Moreover, the SA modified CaMoO4:Eu3+ sample displayed excellent photocatalytic stability after 6 reusability cycles. Our synthesis strategy for protein–inorganic hybrid CaMoO4:Eu3+ opens a new avenue for the production of cutting-edge materials for industrial-scale catalysis and solid-state lighting applications.

Evolution of a simple, efficient and reproducible strategy for the rational design of hierarchically structured metal chalcogenide-based supercapacitors has attracted considerable research interest in recent years. Herein, a facile wet-chemistry approach is employed to design three-dimensional forest-like porous nickel sulfide nanotrees on nickel foam (NiS NTs/Ni foam) for use as a cathode material in hybrid supercapacitors. The growth time plays a crucial role in controlling the surface morphology, and the optimal growth conditions (3 h at 85 °C) led to the growth of forest-like NiS NTs/Ni foam with reliable adherence. The forest-like NiS NTs/Ni foam shows maximum areal and specific capacities of 752.71 μA h cm−2 and 342.1 mA h g−1 at a current density of 4 mA cm−2, with an excellent cycling stability of 89.4%. This result is primarily due to the availability of more surface-active sites in the well-defined hierarchical architecture, which allow the rapid diffusion of electrolyte ions and minimize the electron transport limitation. Utilizing the hierarchical NiS NTs/Ni foam as a cathode and activated carbon-based anode, we further fabricated a hybrid supercapacitor, which demonstrates a wide potential window of 1.6 V with high areal energy and power densities of 0.472 mW h cm−2 and 21.5 mW cm−2, respectively. The fabricated hybrid supercapacitor is successfully utilized to drive various electronic gadgets for real-life applications. The electrochemical performance of a hierarchically structured NiS-based binder-free electrode with our facile approach paves a new pathway for the development of novel metal chalcogenides for high-performance hybrid supercapacitors.

Reduced graphene oxide (RGO) incorporated onto metal–organic framework (MOF)-derived Co3O4 hexagons is prepared via a hydrothermal route for supercapacitor and glucose sensor applications. Various analysis techniques demonstrate that the Co3O4 hexagons were uniformly spread over the thin graphene sheets to assist the electron accessibility of the electrode materials. Under optimized conditions, using 0.1 M KOH electrolyte at a current density of 4 A g−1, a specific capacitance value of 1300 F g−1 is obtained. The fabricated asymmetric supercapacitor cycled reversibly and exhibits high energy and power density values of 65.8 W h kg−1 and 2048 W kg−1, respectively, over the voltage range of −0.1 V to 0.4 V. The asymmetric supercapacitor shows 80.5% capacitance retention even after 5000 cycles at a current density of 4 A g−1, which indicates its high cycling stability in view of the fact that it is binder-free. Furthermore, the RGO–Co3O4 hexagon-modified electrode was optimized to realize the reliable amperometric determination of glucose concentration with a very low detection limit and excellent sensitivity value of 0.4 μM and 1.315 mA mM−1 cm−2, respectively. All of these remarkable performance indicators suggest that RGO–Co3O4 is a promising electrode material for next-generation energy storage devices and electrochemical sensors.