Synergetic Effect of Polyaniline and Graphene in Their Composite Supercapacitor Electrodes: Impact of Components and Parameters of Chemical Oxidative Polymerization

Developments in conducting polymer-, metal oxide-, and carbon nanotube-based composite electrode materials for supercapacitors: a review

Supercapacitors are the latest development in the field of energy storage devices (ESDs). A lot of research has been done in the last few decades to increase the performance of supercapacitors. The electrodes of supercapacitors are modified by composite materials based on conducting polymers, metal oxide nanoparticles, metal-organic frameworks, covalent organic frameworks, MXenes, chalcogenides, carbon nanotubes (CNTs), etc. In comparison to rechargeable batteries, supercapacitors have advantages such as quick charging and high power density. This review is focused on the progress in the development of electrode materials for supercapacitors using composite materials based on conducting polymers, graphene, metal oxide nanoparticles/nanofibres, and CNTs. Moreover, we investigated different types of ESDs as well as their electrochemical energy storage mechanisms and kinetic aspects. We have also discussed the classification of different types of SCs; advantages and drawbacks of SCs and other ESDs; and the use of nanofibres, carbon, CNTs, graphene, metal oxide-nanofibres, and conducting polymers as electrode materials for SCs. Furthermore, modifications in the development of different types of SCs such as pseudo-capacitors, hybrid capacitors, and electrical double-layer capacitors are discussed in detail; both electrolyte-based and electrolyte-free supercapacitors are taken into consideration. This review will help in designing and fabricating high-performance supercapacitors with high energy density and power output, which will act as an alternative to Li-ion batteries in the future.

Ceramics and Nanostructures for Energy Harvesting and Storage

In recent years, the worldwide research in the field of energy harvesting and storage has focused on the development of clean and sustainable methods that can respond to the rising energy demands of humankind [...].

Electrochemical analysis of asymmetric supercapacitors based on BiCoO3@g-C3N4 nanocomposites

Supercapacitors are gaining popularity these days because of their good cycle stability, superior specific capacitance, high power density, and energy density. Herein, we report the synthesis of bismuth cobalt oxide (BiCoO3) combined with graphitic carbon nitride (g-C3N4) by the hydrothermal method. The BiCoO3@g-C3N4 nanocomposite was well characterized using XRD, FE-SEM, FT-IR, and DRS-UV techniques. The supercapacitor properties of the BiCoO3@g-C3N4 nanocomposite were then studied using cyclic voltammetry, galvanic charging-discharging, and impedance spectroscopy techniques. Due to the synergistic effect, BiCoO3@g-C3N4 showed a high specific capacitance value of 341 F g-1 at a current density of 1 A g-1 and excellent retention of specific capacitance (98.82%) after 1000 cycles and a high power density of 1125 W kg-1. Using the impedance spectroscopy technique, the charge transfer resistance of BiCoO3, g-C3N4, and BiCoO3@g-C3N4 was measured. BiCoO3@g-C3N4 showed a low charge transfer resistance compared with BiCoO3 and g-C3N4. The asymmetric supercapacitor (ASC) device was prepared using activated carbon (negative side) and BiCoO3@g-C3N4 (positive side) electrodes. It showed a specific capacitance of 129 F g-1 at 1 A g-1, power density 2800 W kg-1 and energy density 35 W h kg-1. Finally, we conclude that, due to the high specific capacitance, good cycle retention, fast redox activity, and low charge transfer resistance BiCoO3@g-C3N4 is a good electrode material for energy storage applications.

Intrinsically Conducting Polymer Composites as Active Masses in Supercapacitors

Intrinsically conducting polymers ICPs can be combined with further electrochemically active materials into composites for use as active masses in supercapacitor electrodes. Typical examples are inspected with particular attention to the various roles played by the constituents of the composites and to conceivable synergistic effects. Stability of composite electrode materials, as an essential property for practical application, is addressed, taking into account the observed causes and effects of materials degradation.

Mechanochemical Synthesis of Polyanilines and Their Nanocomposites: A Critical Review

The mechanochemical synthesis of polyanilines (PANIs), made by oxidative polymerization of anilines, is reviewed. First, previous knowledge of the polymerization reaction in solution is discussed to understand the effect of different parameters: oxidant/monomer ratio, added acid, oxidant, temperature and water content on the properties of the conducting polymers (molecular weight, degradation, doping/oxidation level, conductivity, and nanostructure). The work on mechanochemical polymerization (MCP) of anilines is analyzed in view of previous data in solution, and published data are critically reconsidered to clarify the interpretation of experimental results. A key factor is the production of acids during polymerization, which is often overlooked. The production of gaseous HCl during MCP of aniline hydrochloride is experimentally observed. Since some experiments involves the addition of small amounts of water, the kinetics and heat balance of the reaction with concentrated solutions were simulated. A simple experiment shows fast (<2 min) heating of the reaction mixture to the boiling point of water and temperature increments are observed during MCP in a mortar. The form and sizes of PANI nanostructures made by MCP or solution are compared. The extensive work on the production of nanocomposites by MCP of anilines together with different nanomaterials (porous clays, graphene, carbon nanotubes, metal, and oxide nanoparticles) is also described.

Fabrication of Polyaniline/Graphene Oxide Nanosheet@ Tea Waste Granules Adsorbent for Groundwater Purification

The reuse and separation of nanomaterials from an aquatic solution is always challenging and may cause nanotoxicity if not separated completely. Nanomaterial immobilization on the surface of a macro-size material could be an effective approach to developing an efficient composite for groundwater purification. Herein, polyaniline and graphene oxide nanosheet immobilized granular tea waste (PANI/GO@GTW) has been synthesized to remove the anionic and cationic contaminants from groundwater. The synthesized materials were characterized by SEM, XRD, XPS, and FTIR spectroscopies. The optimization of experimental conditions was tested for bromide (Br−) removal from synthetic water. The results revealed that Br− adsorption behavior onto the synthesized materials was as follows: PANI/GO < PANI/GTW < PANI < PANI/GO@GTW. The optimum removal of Br− ions was observed at pH 3 with 90 min of saturation time. Br− adsorption onto PANI/GO@GTW followed the pseudo-first-order kinetic and Langmuir isotherm model, and electrostatic interaction was involved in the adsorption process. The optimum adsorption of Br− onto PANI/GO@GTW was found to be 26.80 m/g. The application of PANI/GO@GTW on real groundwater treatment demonstrated the effective removal of anion pollutants such as F−, Cl−, Br−, NO3−, and PO43−. This study revealed that PANI/GO@GTW successfully reduced Br− concentrations in synthetic and real groundwater and can be used for large-scale applications.