Search

Self‐nitrogen‐doped biocarbons are obtained from the watermelon rind via an easy one‐step pyrolysis‐activation process. Porous biocarbon ACW‐2, obtained with a watermelon/potassium hydroxide (KOH) mass ratio of 1:2 at 700 °C, exhibits a large specific surface area of 1303.3 m2 g−1 and is decorated with abundant nitrogen/oxygen‐containing functional groups. When ACW‐2 is used as a supercapacitor electrode, a high specific capacitance of 260 F g−1 is achieved at a current density of 1 A g−1. ACW‐2 also exhibits an ultrahigh cycling stability, and its retention rate is maintained at 93.8% even after 5000 cycles at a scan rate of 100 mV s−1. Furthermore, ACW‐2 acquires a supramaximal specific capacitance (852 F g−1) and a high energy density (12.9 Wh kg−1) when p‐phenylenediamine redox additive is added into the KOH electrolyte. Therefore, the watermelon rind can be used as a promising biomass precursor, and the as‐prepared porous biocarbon is expected to be an outstanding comprehensive electrode material for electrochemical supercapacitors. Self‐nitrogen‐doped porous biocarbon is obtained from the watermelon rind powder via an easy one‐step pyrolysis‐activation process. The large specific surface areas and hierarchical porous structures endow the biocarbon electrode with a high specific capacitance, high rate performance, excellent cycling stability, and improved electrochemical performance using a redox additive electrolyte. [ABSTRACT FROM AUTHOR]

Basing on the theoretical model and empirical analysis, this paper provides a discussion of the hedging effectiveness between the stock market and index future market under the imperfect market conditions. In theoretical analysis, the relation of market imperfection with market microstructure noise and hedging effectiveness is established. In empirical analysis, one approach based on nonparametric estimation is established and applied to real data. The reasonableness of model assumptions and the correction of model conclusions are verified by using 5-minute frequency intra data. Both theoretical and empirical analyses show that the higher the degree of market imperfection, the more necessary to consider the impact of market microstructure noise when using stock index futures to hedge the stock market risk. The empirical results also show that there exists a high degree of imperfection between stock market and stock index future market, but the degree of imperfection has a decreasing trend. [ABSTRACT FROM AUTHOR]