Well-Aligned Cone-Shaped Nanostructure of Polypyrrole/RuO₂ and Its Electrochemical Supercapacitor

Abstract

A new well-aligned cone-shaped nanostructure of polypyrrole (WACNP) has been successfully grown on Au substrate by using a simple, one-step, reliable, and template-free anodic deposition method. The formation mechanism of WACNP is proposed, in which the hydrogen bonding introduced from phosphate buffer solution (PBS) promotes the formation of a well-aligned nanostructure of polypyrrole (PPy), while the steric hindrance effect arisen from high concentration of pyrrole (Py) boosts its vertical alignment and further forms a cone-shaped nanostructure. The 3D, arrayed, nanotubular architecture coated with an ultrathin layer of RuO2 by the magnetron sputtering deposition method was tailored to construct a supercapacitor. The unique structure and design not only reduces the diffusion resistance of electrolytes in the electrode material but also enhances its electrochemical performance. The modification of RuO2 on WACNP results in a capacitance higher than that of WACNP by three times. The specific capacitance of RuO2/WACNP is 15.1 mF cm−2 (∼302 F g−1) measured by the charge−discharge method with an applied current density of 0.5 mA cm−2 over a potential range of −0.2 to 0.7 V, and is greater than that of commercial carbon materials by 2−3 orders of magnitude. The high capacitance and good stability of the RuO2/WACNP electrode is very promising for applications in microsupercapacitor devices.

A review of electrode materials for electrochemical supercapacitors

“…. 264 Zang et al 174 reported a nanostructured polypyrrole/RuO 2 composite that achieved a specific capacitance of 302 F g…”

Spinel NiCo₂O₄ Nanorods for Supercapacitor Applications

“…Two dimensional transition metal oxides (TMOs) like RuO 2 , (Zang et al, 2008) Co 3 O 4 , (Xia et al, 2011) NiO (Zhang et al, 2010 and Mn 3 O 4 (Dubal et al, 2009) have been widely studied as electrodes for supercapacitors. Among all, RuO 2 has been considered as an influential material because of its high specific capacitance and much better cyclic stability (Bi et al, 2010).…”

Properties and Customization of Sensor Materials for Biomedical Applications

“…The resulting sensor showed good linear response to H 2 O 2 over a wide substrate concentration range, although the template deposition method can be cumbersome and may suffer from the potential leaking of the adsorbed enzyme. With regard to template-less polymerization, for instance, pyrrole has received much attention due to the possibility of producing nanostructures during its electrodeposition; fibrillar, rod, and worm-like structures can be prepared using carbonate or phosphate salt solutions (164)(165)(166)(167)(168). The mechanism behind the formation of the nanostructures is still controversial, but it has been hypothesized it may be due to the low density of the charge carriers during the polymer growth and alignment of PPy chains bridged by the phosphate or carbonate anions (164,169).…”