Effects of Electrolytes on the Electrochemical Impedance Properties of NiPcMWCNTs-Modified Glassy Carbon Electrode

Abstract

The supercapacitive properties of synthesized nickel phthalocyanine multiwalled carbon nanotubes nanocomposite on a glassy carbon electrode (NiPcMWCNTs-GCE) in four different electrolytes were investigated. The successful synthesis of the NiPcMWCNTs nanocomposite was confirmed by UV/vis electrode spectroscopy, SEM, TEM, EDX, and XRD techniques. The supercapacitive behaviors of the modified electrodes were examined in PBS, H₂SO₄, Na₂SO₄, and SAB electrolytes via CV and EIS techniques. The highest specific capacitance of 6.80 F g^-1 was achieved for the GCE-NiPcMWCNTs electrode in 5 mM [Fe(CN)₆]^4-/3- prepared in 0.1 M PBS (pH 7). Charge transfer resistance R_ct values of 0.06, 0.36, 0.61, and 1.98 kΩ were obtained for the GCE-NiPcMWCNTs in H₂SO₄, SAB, Na₂SO₄, and PBS electrolytes, respectively. Power density values, otherwise known as the "knee" frequency f°, of 21.2, 6.87, 2.22, and 1.68 Hz were also obtained for GCE-NiPcMWCNTs in H₂SO₄, Na₂SO₄, PBS, and SAB electrolytes, respectively. GCE-NiPcMWCNTs demonstrated the fastest electron transport capability and the highest power density in H₂SO₄ compared to the other electrolytes. Hence, GCE-NiPcMWCNTs-modified electrodes had high stability, high energy and power densities, and a large specific capacitance.

Keywords: bromate; electrochemical impedance spectroscopy; multiwalled carbon nanotubes; nickel phthalocyanine; supercapacitor.