Fig. 4
From: Supercapacitors with alternating current line-filtering performance
Reproduced with permission from Ref [67]. Copyright 2016. Macmillan Publishers Limited
a Schematic of the N-dopant specifically unzipping of NCNTs; b SEM image of the unzipped nanostructure; c AFM image of the unzipped nanostructure; blue and red arrows indicate NCNT and graphene nanoribbons, respectively; d AC impedance phase angle versus the frequency (vertical dotted line indicates 120-Hz frequency); e imaginary part (C″) of specific capacitance versus the frequency; and f specific capacitance versus the frequency assuming a series RC circuit model.