Sacrificial template synthesis of short mesoporous NiO nanotubes and their application in electrochemical capacitors

We developed a sacrificial template strategy to synthesize short NiO nanotubes (S-NiO NTs) with mesopores in sidewalls by using short carbon NTs as template for electrochemical capacitors. Further physical characterizations exhibited that as-synthesized S-NiO NTs owned a specific surface area of 150 m2 g−1 and hierarchical (meso- and macro-) porosity. Electrochemical data presented that such NTs delivered a specific capacitance of 903 F g−1 at 1 A g−1, much larger than those of long NiO NTs and NiO nanoparticles. The capacity retention of ca. 88%, when the current density increased from 1 to 4 A g−1, indicated high rate capability of the unique S-NiO NTs electrode. Furthermore, a capacitance degradation of ca. 6% after 2000 charge–discharge cycles at 4 A g−1 demonstrated their desirable electrochemical stability. The short tubular and hierarchical porous feature of the S-NiO NTs resulted in the high electrochemical utilization for energy storage even at high rates.