The Effect of Modifications of Activated Carbon Materials on the Capacitive Performance: Surface, Microstructure, and Wettability

Abstract

In this review, the efforts done by different research groups to enhance the performance of the electric double-layer capacitors (EDLCs), regarding the effect of the modification of activated carbon structures on the electrochemical properties, are summarized. Activated carbon materials with various porous textures, surface chemistry, and microstructure have been synthesized using several different techniques by different researchers. Micro-, meso-, and macroporous textures can be obtained through the activation/carbonization process using various activating agents. The surface chemistry of activated carbon materials can be modified via: (i) the carbonization of heteroatom-enriched compounds, (ii) post-treatment of carbon materials with reactive heteroatom sources, and (iii) activated carbon combined both with metal oxide materials dan conducting polymers to obtain composites. Intending to improve the EDLCs performance, the introduction of heteroatoms into an activated carbon matrix and composited activated carbon with either metal oxide materials or conducting polymers introduced a pseudo-capacitance effect, which is an additional contribution to the dominant double-layer capacitance. Such tricks offer high capacitance due to the presence of both electrical double layer charge storage mechanism and faradic charge transfer. The surface modification by attaching suitable heteroatoms such as phosphorus species increases the cell operating voltage, thereby improving the cell performance. To establish a detailed understanding of how one can modify the activated carbon structure regarding its porous textures, the surface chemistry, the wettability, and microstructure enable to enhance the performance of the EDLCs is discussed here in detail. This review discusses the basic key parameters which are considered to evaluate the performance of EDLCs such as cell capacitance, operating voltage, equivalent series resistance, power density, and energy density, and how these are affected by the modification of the activated carbon framework.

Multistage Activation of Anthracite Coal-Based Activated Carbon for High-Performance Supercapacitor Applications

“…The prepared working electrode was then soaked in the electrolyte solution at room temperature for over 12 h. The electrochemical experiments were carried out by a three-electrode system. The three-electrode configuration is useful in the investigation of the chemistry of the active electrode surface as well as the redox behavior of the active electrode material . Two different aqueous electrolytes were used in the electrochemical experiments.…”

Activated porous carbon supported Pd and ZnO nanocatalysts for trace sensing of carbaryl pesticide in water and food products

“…The peak current decreased after the modification of the GCE with APC with an increase in the Δ E , which may be attributed to the low conductivity of the latter. 59 While coating the APC with ZnO NPs, peak currents were greatly increased (around 76% for I pa and 63% for I pc as compared to GCE bare) and electrode performance was improved, which can be explained by the enhanced conductivity issued by ZnO NPs due to their intrinsic electrocatalytic properties. This suggested that the metal oxide had facilitated electron transfer and enhanced the electroactive surface area of the electrode.…”

“…The presence of micro-and mesopore delays the charge transfer, which limits accessibility to the electrode surface. 59 Once ZnO was added to the carbon support, the semicircle had strongly diminished and revealed an R ct value of 23.09 ohm cm 2 because the conductivity of the electrode increased due to ZnO NPs, which facilitated electron transfer between the electrochemical probe redox and the electrode surface. Moreover, the presence of Pd NPs in the Pd/ZnO/APC nanocomposite led to further suppression in the semicircle with a low R ct of 14.56 ohm cm 2 .…”

Functionalised graphite felt anodes for enhanced power generation in membrane-less soil microbial fuel cells

“…As expected, the functionalization of graphite felt with Co 3 O 4 led to a decrease in the hydrophobicity, corresponding to a reduction of the contact angle to 116 ± 0.6° from a value of 139 ± 0.1° for plain GF (Figure 2a). This improvement in the electrode wettability could result from the oxygen atoms introduced by Co 3 O 4 that could alter the electrostatic field at the surface of graphite felt and facilitate interaction between the electrode material and water molecules 45,28 . The electrodeposition of PANI further decreased the surface hydrophobicity, with PANI-Co 3 O 4 -GF reaching a contact angle of 97 ± 0.9.…”