Synthesis, Structural, and Morphological Characterizations of Reduced Graphene Oxide-Supported Polypyrrole Anode Catalysts for Improved Microbial Fuel Cell Performances

Abstract

The conductive polypyrrole (PPy)/reduced graphene oxide (rGO) composites were synthesized through simple, environmentally benign, time and cost efficient, in situ polymerization and bioreduction techniques. The pyrrole monomer effectively adsorbed over the negatively charged GO sheets through electrostatic and π−π interactions was polymerized into polypyrrole in its adsorbed state. The obtained morphological images of the rGO/PPy composite ensured that the entire surface of the active carbon support was covered by PPy. The removal of oxygen functionalities from GO with the aid of Ocimum tenuiflorum extract was ascertained through FT-IR and UV−vis absorption spectroscopic studies. The rGO/PPy composite exhibited higher electrocatalytic oxidation current as evidenced from the cyclic voltammetric analysis. The number of actives sites and continuous carrier channels of the rGO/ PPy composite exhibited a maximum MFC power density of 1068 mW/m 2 , which is almost two-fold higher than that of bare PPy. The strong active carbon support prohibited the swelling and shrinkage of the conductive polymer PPy and provided the strong physico and electrochemical robustness of the rGO/PPy composite, which increased the MFC durability performances up to 300 h. These findings have not only provided fundamental knowledge on the preparation rGO-based composites through a green approach but also have found possible applications in large-scale green energy devices.

Enhanced Performance of a Single Chamber Microbial Fuel Cell Using NiWO4/Reduced Graphene Oxide Coated Carbon Cloth Anode

“…The characteristics band at 3,200 and 1,400 cm −1 for –OH stretching vibration and deformation can be explicitly observed in the GO spectrum. There have some peaks at 1,166cm −1 , 1,044 cm −1 (C‐O stretching vibration), 1,400 cm −1 (C–OH stretching), 1,626 cm −1 (skeletal vibration), 1,725 cm −1 (C=O stretching vibration from carbonyl and carboxylic bond), these peaks indicate the presence of oxygen‐containing functional groups . The peaks of oxygen‐containing functional groups in rGO spectra at 1,044, 1,626, and 1,725 cm −1 were considerably reduced which confirms the deoxgenation of GO to rGO during the hydrothermal process.…”

“…Various types of electrode material are used as anodes in MFCs, among them carbon based materials, like carbon cloth (CC), carbon felt and carbon paper, have been mostly adopted due to their good electrical conductivity, non‐corrosiveness and biocompatibility properties . Further, modifying its surface morphology and property enhances drastically the MFC performance might be due to the increase in the attachment of bacteria that facilitates the extracellular electron transfer mechanism , , .…”

Applications of Graphene-Modified Electrodes in Microbial Fuel Cells

“…The hydrophobic graphite powder can be changed to hydrophilic graphite oxide under the influence of strong oxidants, e.g., concentrated sulfuric acid and potassium permanganate, which break the π bond between the graphite sheets and also introduce abundant epoxy, hydroxyl, and carbonyl groups [48]. However, the hydrophilic functional groups introduced disrupt the conjugated sp 2 network and degrade the electrical properties of the graphite sheets [42]. Hence, to enhance the electrical properties, first, the graphite oxide solution is homogeneously dispersed by ultrasonic treatment to form a graphene oxide colloidal solution, and then reducing agents are introduced to remove the oxygen functional groups, resulting in a reduced graphene oxide (rGO).…”

“…Graphene, discovered in 2004 by Geim and Novoselov [40], is a two-dimensional (2D) single-atom-thick flat material consisting of sp 2 hybridized carbon atoms arranged in a honeycomb lattice [41,42,43]; at present, graphene is the thinnest material in the world. Its theoretical thickness value, band length, and bond angle are 0.335 nm, 0.142 nm, and 120°, respectively [44].…”

“…However, the monolayer graphene sheet is known to irreversibly agglomerate or form multilayer graphite through strong π-π stacking and van der Waals interactions [45]. Graphene oxide (GO) is an important derivative of graphene that contains heavy epoxy and hydroxyl functional groups on the basal planes, and carbonyl and carboxyl groups on the sheet edges, which make it possible to fabricate graphene based materials on a large scale [42]. Although these functional groups increase its hydrophilic character, the conjugated sp 2 network of the individual graphene basal planes is disrupted and the electrical properties of GO are decreased.…”