Xiaozhong Zhou

Cotton-based porous activated carbon with a large specific surface area as an electrode material for high-performance supercapacitors

Cotton-based porous activated carbons (CACs) are prepared through a simple chemical activation method using cotton fiber as carbon source and ZnCl2 as activating agent. Powder X-ray diffraction, scanning electron microscopy, and N2 adsorption–desorption tests demonstrate that the carbons activated with different amounts of ZnCl2 have a large number of mesopores, notably, a maximum specific surface area of 2548.6 m2 g−1 and ultrahigh pore volume of 1.54 cm3 g−1 for CAC2 sample are obtained when the cotton/ZnCl2 mass ratio is 1 : 2. As an electrode material for supercapacitors, the CAC2 possesses a high specific capacitance of 239 F g−1 at 0.5 A g−1 and good rate capability (82% capacitance retention even at 8 A g−1) in 2 mol L−1 KOH aqueous electrolyte. Moreover, the as-assembled CAC2//CAC2 symmetric supercapacitor exhibits a high energy density of 13.75 Wh kg−1 at a power density of 225 W kg−1 operated at the voltage range of 0 to 1.8 V in 0.5 mol L−1 Na2SO4 aqueous electrolyte and an excellent cyclability retaining about 93% initial capacitance after 5000 cycles.

A novel fabrication of nitrogen-containing carbon nanospheres with high rate capability as electrode materials for supercapacitors

Nitrogen-containing polyaniline-based carbon nanospheres (C-PANI) with diameters of about 200 nm are prepared through a direct carbonization method using polyaniline (PANI) nanospheres as carbon precursors at different temperatures. The PANI nanospheres are synthesized via in situ oxidation polymerization of aniline in the presence of sodium carboxymethyl cellulose as a polymerization template. The C-PANI with 6.69% nitrogen content obtained at 800 °C (C-PANI-800) can achieve a high capacitance of 359 F g−1 at the current density of 1 A g−1 in 6 M aqueous KOH electrolyte, meanwhile maintaining excellent rate capability (81% retention at 20 A g−1). Furthermore, a symmetric supercapacitor fabricated with C-PANI-800 electrodes exhibits an energy density of 17.5 W h kg−1 at a power density of 227 W kg−1 and superior cycle stability (only 4% loss after 5000 cycles), operating in the voltage range of 0–1.8 V in 0.5 mol L−1 Na2SO4 aqueous electrolyte.

Carbonized phenanthroline functionalized carbon as an alternative support: a strategy to intensify Pt activity and durability for methanol oxidation

In this study, a carbonized phenanthroline functionalized carbon support (CPF-C) has been prepared, which was used to load Pt nanoparticles to serve as an electrocatalyst for methanol oxidation. The results show that the performance of Pt in Pt/CPF-C is improved relative to that of industrially adopted Pt/C. The increase is mainly interpreted in terms of the synergistic effect between the stabilized Pt nanoparticles and nitrogen-functionalized CPF-C support. The novel CPF-C support presented here offers an alternative to the conventional carbon support to improve the performance of Pt applied in direct methanol fuel cells.

Anchoring Sb6O13 Nanocrystals on Graphene Sheets for Enhanced Lithium Storage

Sb6O13/reduced graphene oxide (Sb6O13/rGO) nanocomposite was synthesized by the solvothermal method using Sb2O3 and graphene oxide as raw material. On the basis of the physical and electrochemical characterizations, Sb6O13 nanocrystals of 10-20 nm size were uniformly anchored on rGO sheets, and the nanocomposite displayed a large reversible specific capacity of 1271 mA h g-1 and an excellent cyclability of 1090 mA h g-1 after 140 cycles at 100 mA g-1 when proposed as a potential anode material for lithium ion batteries, emphasizing the advantages of anchoring of Sb6O13 nanocrystals on rGO sheets for the maximum utilization of electrochemically active Sb6O13 and rGO for lithium storage.

Sb2O3 nanoparticles anchored on graphene sheets via alcohol dissolution-reprecipitation method for excellent lithium storage properties

Sb2O3 nanoparticles are uniformly anchored on reduced graphene oxide (rGO) sheets via a facile and ecofriendly route based on the alcohol dissolution-reprecipitation method. Such obtained Sb2O3/rGO composite demonstrates a highly reversible specific capacity (1355 mA h g-1 at 100 mA g-1), good rate capability, and superior life cycle (525 mA h g-1 after 700 cycles at 600 mA g-1) when used an anode electrode for lithium-ion batteries (LIBs). The outstanding electrochemical properties of Sb2O3/rGO composite could be attributed to its unique structure in which the strong electronic coupling effect between Sb2O3 and rGO leads to an enhanced electronic conductivity, structure stability, and electrochemical activity during reversible conversion-alloying reactions. Also, these findings are helpful in both developing novel high-performance electrodes for LIBs and synthesizing functional materials in an ecofriendly and economical way.