Effect of porosity variation on the electrochemical behavior of vertically aligned multi-walled carbon nanotubes

Electrochemical charge storage characteristics of vertically aligned multi-walled carbon nanotubes (MWCNTs) as a function of varying diameter and spacing are reported. It was observed that the specific capacitance of the MWCNTs increased as both diameter and inter-tube spacing decreased. The MWCNT films with 230 nm inter-MWCNT spacing exhibited specific capacitance of 228 F/g versus 70 F/g for 506 nm spacing, when tested in a non-aqueous electrolyte. Further, a trend in specific capacitance versus pore size is proposed. Coupled with previously reported trends observed in the sub-10 nm pore size regime, this is expected to offer better understanding of electrochemical behavior of porous carbon materials over a wide range of pore sizes.

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► Vertically aligned carbon nanotubes of varying porosity were grown.
► Carbon nanotube morphology was analyzed using computer assisted image analysis.
► Specific capacitance increased with decreasing pore size and nanotube diameter.