Electrochemical performance of facile developed aqueous asymmetric (Fe,Cr)2O3//MnO2 supercapacitor

Fabrication of an ultra-stable composite electrode material of La2O3/Co3O4/graphene on nickel foam for high-performance supercapacitors

A three-dimensional lily-like structure was constructed by the novel combination of La2O3, Co3O4, and graphene on nickel foam (LCGN) through hydrothermal synthesis and thermal annealing.

Highly active hollow mesoporous NiFeCr hydroxide as an electrode material for the oxygen evolution reaction and a redox capacitor

A hollow mesoporous trimetallic NiFeCr hydroxide electrode is prepared via a four-step procedure involving the fast electrodeposition of an Ni/Cr/Fe alloy onto a nickel foam substrate, followed by dealloying, oxidation, and activation. The title electrode shows an ultralow onset overpotential of 210 mV for the oxygen evolution reaction and a high specific capacity of 1768 F g^-1 as a redox capacitor.

The Application of Metal-Organic Frameworks and Their Derivatives for Supercapacitors

Supercapacitors (SCs), one of the most popular types of energy-storage devices, present lots of advantages, such as large power density and fast charge/discharge capability. Being the promising SCs electrode materials, metal-organic frameworks (MOFs) and their derivatives have gained ever-increasing attention due to their large specific surface area, controllable porous structure and rich diversity. Herein, the recent development of MOFs-based materials and their application in SCs as the electrode are reviewed and summarized. The preparation method, the morphology of the materials and the electrical performance of various MOFs and their derivatives (such as carbon, metal oxide/hydroxide and metal sulfide) are briefly discussed. Most of recent works concentrate on Ni-, Co- and Mn-MOFs and their composites/derivatives. Conclusions and our outlook for the researches are also given, which would be a valuable guideline for the rational design of MOFs materials for SCs in the near future.

An Enhanced Reduction-Adsorption Strategy for Cr(VI): Fabrication and Application of L-Cysteine-doped Carbon@Polypyrrole with a Core/Shell Composite Structure

Reclamation and recycling of heavy metal ions can offer environmental protection and sustainable development. Here, we report the preparation of L-cysteine (L-cys)-doped glucose carbon sphere (GCS)@polypyrrole (PPy) composites (GCS@PPy/L-cys). The adsorption performance and mechanism of GCS@PPy/L-cys toward Cr(VI) from water were investigated in detail. The chromate enrichment on GCS@PPy is significantly facilitated by doping with L-cys, which prevents the oxidative collapse of the structure. This approach leads to many reduction-adsorption sites that reduce the highly hazardous Cr(VI) into less toxic Cr(III). More significantly, the composite can be reused to fabricate supercapacitors that avoid secondary pollution. This strategy offers high-efficiency treatment and sustainable utilization of hypervalent metals in water.

Asymmetric supercapacitors with high energy densities

The low energy densities of supercapacitors (SCs) are generally limited by the used anodes. To develop SCs with high energy densities, Fe3+ modified V2O5@GQDs (m-V2O5@GQDs) and ZIF-67-derived nanoporous carbon loaded with Mn3O4 (C/N-Mn3O4) were synthesized. After their detailed characterization using electron microscopy, X-ray methods and electrochemical techniques, they were further utilized as the anode and the cathode, respectively, to construct asymmetric supercapacitors (ASCs). The as-synthesized m-V2O5@GQDs improve the poor conductivity of V2O5, contributing greatly to a specific capacitance of 761 F g-1 at a current density of 2 A g-1. With application of a cell voltage of 2 V, an energy density of up to 99.4 W h kg-1 is achieved at a power density of 1000 W kg-1. Such ASCs also exhibit outstanding cycling performance (95% of initial capacitance even after 10 000 charging/discharging cycles). This study thus provides a new way to design and construct ASCs with high energy densities.