**1. Introduction**

In the modern era, an integral part of human life is smart technology. Accordingly, advanced technologies are always searching for smart and well-fabricated materials to satisfy the growing demand [1–3]. The development of novel materials with improved electrochemical performance is required to address the critical issue of pollution. There is a growing need for sustainable and renewable energy storage solutions in hybrid automobiles and portable electronic devices [4], necessitating the development of innovative materials with better electrochemical capabilities, such as electrochemical capacitors or supercapacitors [5]. A supercapacitor is a type of energy storage system that combines both battery and conventional capacitor properties [6,7]. Electrochemical capacitors, or supercapacitors, have been extensively used in high-power energy storage materials. As such, supercapacitors are one of the most promising candidates among the various systems that lead the state-of-the-art electrical energy storage systems due to their environmental friendliness, sustainable cycle stability, low cost [8], excellent cycling life [9], high power density, and fast charging/discharging rate [5,10]. Supercapacitors are classified as electrochemical double-layer capacitors (EDLCs) or pseudosupercapacitors based on their charge storage mechanism [11,12]. The electrostatic separation of ionic and electronic charges at the electrode and electrolyte interfaces provides energy storage in EDLCs, and the efficiency of such devices is dictated by the surface area involved in the charge accumulation process

**Citation:** Ullah, R.; Khan, N.; Khattak, R.; Khan, M.; Khan, M.S.; Ali, O.M. Preparation of Electrochemical Supercapacitor Based on Polypyrrole/Gum Arabic Composites. *Polymers* **2022**, *14*, 242. https://doi.org/10.3390/ polym14020242

Academic Editor: Jung-Chang Wang

Received: 7 December 2021 Accepted: 4 January 2022 Published: 7 January 2022

**Publisher's Note:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

**Copyright:** © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

between the electrodes and electrolyte [13]. However, a faradaic (redox) reaction happens at the electrode surfaces in the pseudocapacitor process, resulting in energy storage effects. The behavior of pseudocapacitors is determined by the electrode material, which exhibits electrochemical signatures, and the charge storage is mostly determined by the applied voltage [14,15]. Conducting polymers (CPs) are the best choice for these two types of electrochemical devices because they possess both ionic and electronic conductivities. Doping various ionic or non-ionic materials or fillers into CPs can further increase their conductivities [16].

Among the various CPs, PPy is extensively studied because of its ease of preparation, stabilized oxide form, good oxidation and reduction properties [17], and the capability to provide high conductivity [18], commercially easily available monomers [19], as well as optical and good electrical properties [20]. PPy consists of alternate single and double-bonded macromolecular chain structures. PPy excellent performance is due to its structure, but it also has some drawbacks, such as lower capacitance and poor cycling stability, which limit its use in high-performance supercapacitors [21]. It is well known that biodegradable polymers are preferable to non-biodegradable polymers. Some of the biodegradable polymers that are used as supercapacitorsare chitosan (CS) [22], PVA [23], and glycerol [24]. On the other hand, gum arabic (GA) in the composite form can be used to alleviate the pure PPy problem. The insertion of GA into the PPy matrix can be a promising choice due to its high contact area, chemical stability, thermal stability, and mechanical stability, as well as its high energy storage capabilities at the electrode/electrolyte interface.

In this research work, an electrode for a supercapacitor based on PPy/GA composites was fabricated by inverse emulsion polymerization. The electrochemical characteristics, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanometric charging–discharging (GCD) properties of the fabricated PPy/GA composites based supercapacitor devices were investigated. The synthesized materials could be promising electrode materials for high-performance supercapacitor applications, which have not been previously reported.
