Dual Capacitive Behavior of Hollow Porous Gold Nanoparticle/Multi-Walled Carbon Nanotube Composite Films as Anode and Cathode Electrode Materials for Supercapacitors

In this paper, composites of multi-walled carbon nanotubes decorated with hollow porous gold nanoparticles (HPAuNPs/MWCNTs) were prepared using wet chemistry methods, and their capacitive properties were evaluated in Na2SO4 aqueous solution on glassy carbon (GC) electrodes as both cathode and anode materials by cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS) techniques. Also, the MWCNTs were studied under similar experimental conditions for comparison. The results revealed that the charge storage mechanisms of the MWCNTs/GC and HPAuNPs/MWCNTs/GC electrodes were electrostatic in the negative potential window, whereas they exhibited pseudocapacitive energy storage behavior in the positive potential region. Moreover, the HPAuNPs/MWCNTs/GC electrode yielded specific capacitance values of 57 and 49 F g−1 at a scan rate of 20 mV s−1 in the cathodic and anodic potential windows, respectively, which were higher than those of the MWCNTs/GC electrode (~9 F g−1). Graphic Abstract: [Figure not available: see fulltext.].