Water-in-salt electrolyte ion-matched N/O codoped porous carbons for high-performance supercapacitors

Construction of three-dimensional MgIn2S4 nanoflowers/two-dimensional oxygen-doped g-C3N4 nanosheets direct Z-scheme heterojunctions for efficient Cr(VI) reduction: Insight into the role of superoxide radicals

Environmental crisis aroused from carcinogenic and mutagenic heavy metal Cr(VI)-containing wastewater has attracted great attention. Herein, a direct Z-scheme three-dimensional MgIn₂S₄ nanoflowers/two-dimensional oxygen-doped g-C₃N₄ nanosheets heterostructured composite photocatalysts were fabricated for Cr(VI) photoreduction. The crystalline structure, morphology, specific surface areas, chemical components, optical properties, as well as photoelectrochemical performance of the fabricated photocatalyst were systematically studied. All the hybrids photocatalysts exhibited superior Cr(VI) photoreduction performance than a single component. The optimal sample showed 2.0 and 343.7 times increasing than three-dimensional MgIn₂S₄ nanoflowers and two-dimensional oxygen-doped g-C₃N₄ nanosheets, respectively. The enhancement of the Cr(VI) photoreduction performance could be ascribed to the enhanced specific surface areas, the improved light absorption, and the Z-scheme charge carriers' separation and migration pathway. Moreover, the role of superoxide radicals was investigated. It is speculated that this research would present a new sight toward photocatalytic Cr(VI) reduction.

In Situ Formation of "Dimethyl Sulfoxide/Water-in-Salt"-Based Chitosan Hydrogel Electrolyte for Advanced All-Solid-State Supercapacitors

Biodegradable hydrogel electrolytes are particularly attractive in the fabrication of all-solid-state supercapacitors due to environmental benignity and avoiding of leakage. The introduction of "water-in-salt" (WIS) electrolytes into hydrogels will further broaden the electrochemical stability window of aqueous supercapacitors significantly. Meanwhile, the addition of an organic co-solvent can effectively overcome the inevitable salt precipitation and extend the temperature adaptability. Herein, an in situ cross-linking approach was demonstrated without any extra binder to obtain a "dimethyl sulfoxide/water-in-salt"-based (DWIS) chitosan hydrogel electrolyte. Interestingly, the addition of 4-7 mol L^-1 of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salts not only conforms to the criterion of WIS, but also promoted the successful gelation through the supramolecular complexation between Li⁺ -solvated complexes and chitosan chains. A hydrogel-based all-solid-state supercapacitor was fabricated using the DWIS chitosan hydrogel as the electrolyte and separator while nitrogen-doped graphene hydrogel (NG) was used as the electrode. The optimized supercapacitor with a wide operating voltage of 2.1 V showed a high specific capacitance of 107.6 F g^-1 at 1 A g^-1 , remarkable capacitance retention of 80.1 % after 5000 cycles, a superior energy density of 62.9 Wh kg^-1 at a power density of 1025.5 W kg^-1 , and excellent temperature stability in the range of -20 to 70 °C. These findings suggest that the as-prepared hydrogel electrolyte holds great potential in the practical application of high-performance solid-state energy storage devices.

Fatsia Japonica-Derived Hierarchical Porous Carbon for Supercapacitors With High Energy Density and Long Cycle Life

Fatsia Japonica seed, which is mainly composed of glucose, has potential as a porous carbon matrix precursor for supercapacitors that can achieve high-value utilization. Cost-effective hierarchical porous carbon materials (HPC) were prepared from Fatsia Japonica by annealing at high temperature. The pore size and distribution of the HPC can be precisely controlled and adjusted by altering the activation temperature. The HPC obtained at 600°C showed favorable features for electrochemical energy storage, with a surface area of 870.3 m2/g. The HPC for supercapacitors (a three-electrode system) exhibited good specific capacitance of 140 F/g at a current density of 1 A/g and a long cycling life stability (87.5% remained after 10,000 cycles). In addition, the HPC electrode showed an excellent energy density of 23 Wh/Kg. Such hierarchical porous biomass-derived carbon would be a good candidate for application in the electrodes of supercapacitors due to its simple preparation process and the outstanding electrochemical performance.

Design of a redox-active “water-in-salt” hydrogel polymer electrolyte for superior-performance quasi-solid-state supercapacitors

A carbon-based quasi-solid-state supercapacitor with a redox-active “water-in-salt” hydrogel polymer electrolyte exhibiting wide operating voltage and high specific energy.

Elaeocarpus tectorius derived phosphorus-doped carbon as an electrode material for an asymmetric supercapacitor

Phosphorus-doped activated carbon from unexplored biomass was prepared, and it exhibits excellent electrochemical properties for green energy technology.