Shan Ji

Ranunculus flower-like Ni(OH)2@Mn2O3 as a high specific capacitance cathode material for alkaline supercapacitors

A novel core–shell Ni(OH)2@Mn2O3 material is presented that bears a particle morphology of striking resemblance to Ranunculus flower heads. A 7.8 wt% of Mn2O3 content in Ni(OH)2@Mn2O3 resulted in an impressively high specific capacitance of 1219.1 F g−1 at 2 A g−1 in alkaline electrolytes.

A cost effective, highly porous, manganese oxide/carbon supercapacitor material with high rate capability

A porous, cube-shaped, Mn2O3/carbon material of varying sizes was prepared via co-synthesis, in which Mn2O3 homogeneously contacts with carbon. Upon a 100 fold increase in current density, specific capacitance dropped by only 39.0%, and the material showed excellent long-term cycle stability of 89% capacitance retention after 2000 cycles at 2 A g−1.

N-doped porous carbon material made from fish-bones and its highly electrocatalytic performance in the oxygen reduction reaction

A N-doped porous carbon material was prepared by pyrolysis of fish bones, a natural material and sustainable source. The morphology and structure of the N-doped porous carbon were investigated by scanning electron microscopy, X-ray diffraction, Raman spectroscopy and N2 isotherms. The mass content of N in the obtained sample measured by X-ray photoelectron spectroscopy is about 6.02%. Electrochemical characterization reveals that the obtained N-doped porous carbon possesses excellent catalytic activity towards oxygen reduction reaction in alkaline medium, as well as long-term stability in catalysis.

Manganese dioxide core–shell nanostructure to achieve excellent cycling stability for asymmetric supercapacitor applications

This study presents a facile and low-cost method to prepare core–shell nano-structured β-MnO2@δ-MnO2, in which β-MnO2 nano-wires act as the cores to form 3D networks and δ-MnO2 as the shells. A uniform hierarchical β-MnO2@δ-MnO2 core–shell structure can be obtained after layered structured δ-MnO2 is deposited on the surface of the needle-like β-MnO2 particles via a simple wet chemistry method at room temperature. The as-prepared materials were physically and electrochemically characterized by nitrogen isotherm analysis, X-ray diffraction, scanning electron microscopy, transmission electron microscopy and potentiostatically/galvanostatically. Under our conditions, the electrochemical results showed that the specific capacitance of β-MnO2@δ-MnO2 was ∼200 F g−1 and the specific capacitance retention was almost 100% after 5000 cycles at a current density of 1 A g−1 in 1 M LiOH electrolyte. The excellent cycling stability of β-MnO2@δ-MnO2 showed that the new material has great potential for use in electrochemical supercapacitors, and the facile wet chemistry method used to synthesize β-MnO2@δ-MnO2 could be a promising method to produce highly stable MnO2-based electrode materials in large batches.

Toward high practical capacitance of Ni(OH)2 using highly conductive CoB nanochain supports

Ultrathin porous Ni(OH)2 sheets were grown on the surface of nano-chain CoB as cores via a facile two-step solution-based method at ambient conditions. The resultant CoB@Ni(OH)2 of 27.89 wt% Ni(OH)2 loading has a high specific capacitance of 1504.4 F g−1 at 0.5 A g−1, 1293.7 F g−1 at 2 A g−1 and 746.8 F g−1 at 6 A g−1.