Direct Polymerized Polyaniline Nanostructures on Modified Indium-Tin Oxide Surface for Electrochemical Supercapacitors

Fundamental and experimental research on electrochemical supercapacitors ESs, also called ultracapacitors, has acquired considerable attention because of high power density and long cycle life compared to other electrochemical energy storage systems, including batteries. High power requirements for a short duration such as camera flash equipment, pulsed light generators, fire/smoke alarms, and backup power sources for computer memory are some of the decent applications of ESs. 1 The capacitance in ESs originates either from the charging or discharging of the electrical double layers or from the faradaic redox reactions. In the former case, the capacitance is derived from charge separation in the carbon-based materials, and in the latter, a faradaic process takes place due to redox reactions based on metal oxides and electronically conducting polymers. Among various conducting polymers, polyaniline PANI is one of the most promising materials for ESs because of its highcapacitive, eco-friendly characteristics, low cost, and easy processing. 2-5 In recent years, a great deal of research has concentrated on the fine-tuning synthesis of tubular morphologies by controlling reaction mechanisms. Among these studies, template-free chemical synthesis has been favored to polymerize PANI in the presence of large and bulky acids. For instance, a simple and practical development method using interfacial polymerization for making