Performance evaluation of poly(aniline-co-pyrrole) wrapped titanium dioxide nanocomposite as an air-cathode catalyst material for microbial fuel cell.

A simple, inexpensive in situ oxidative polymerization of aniline and pyrrole using ammonium persulfate (APS) as oxidant and hydrochloric acid (HCl) as dopant has been used to synthesize a hybrid (PAni-Co-PPy)@TiO2 nanocomposite with titanium oxide (TiO2) nanoparticles (NPs) wrapped into (PAni-Co-PPy) copolymer. The synthesized nanocomposite has been shown with higher oxygen reduction reactions (ORR) as an excellent cathode material for higher performance in the complex of (PAni-Co-PPy)+/TiO2(O-). The charge transport phenomenon between TiO2 and (PAni-Co-PPy)+ were found adequate with subsequent delocalization of electron/s at PAni and PPy. The self-doping nature of TiO2 (O-) played a vital role in oxygen adsorption and desorption process. With higher electrical conductivity and surface area, these were tested in microbial fuel cells (MFCs) for ORRs at cathode. This yielded a relatively higher current and power density output as compared to PAni@TiO2, PPy@TiO2, and commercially available Pt/C cathode catalysts in MFC system. In overall, the prepared (PAni-Co-PPy)@TiO2 nano-hybrid cathode delivered ~2.03 fold higher power density as compared to Pt/C catalyst, i.e. ~987.36 ± 49 mW/m2 against ~481.02 ± 24 mW/m2. The properties of electro-catalysts established an improved synergetic effect between TiO2 NPs and (PAni-Co-PPy). In effect, the enhanced surface area and electrochemical properties of the prepared (PAni-Co-PPy)@TiO2 nano-hybrid system is depicted here as an effective cathode catalyst in MFCs for improved performance.

Sulfonated graphene oxide and titanium dioxide coated with nanostructured polyaniline nanocomposites as an efficient cathode catalyst in microbial fuel cells.

In this study, sulfonated graphene oxide (SGO) was synthesized as potential conducting matrix to improve the properties of catalyst for single chamber microbial fuel cells (SC-MFCs). Here, TiO2 and Polyaniline (PAni) nanoparticles were anchored over SGO and the resulting SGO-TiO2-PAni nanocomposites were used as a potential cathode catalyst in MFCs. We have also examined the performance of SGO-TiO2-PAni compared to GO-TiO2-PAni and TiO2-PAni catalyst. The structural and morphological analyses were examined using a variety of characterization techniques. TiO2 nanoparticles bridged PAni and SGO through hydrogen bonding/electrostatic interaction and improved the thermal stability of SGO-TiO2-PAni catalyst. The electrochemical characterizations of these nanocatalysts suggest that the SGO-TiO2-PAni showed higher reduction current value (-0.46 mA), enhanced stability, and lower internal resistance (46.2 Ω) in comparison to GO-TiO2-PAni and TiO2-PAni towards oxygen reduction reactions (ORR). Consequently, MFC using SGO-TiO2-PAni demonstrated a maximum power density of 904.18 mWm-2 than that of GO-TiO2-PAni (734.12 mWm-2), TiO2-PAni (561.5 mWm-2) and Pt/C (483.5 mWm-2). The enhanced catalytic activity of SGO-TiO2-PAni catalyst was ascribed to the high electronic conductivity and long-term permanence of the nanocomposite. These superior electrochemical results suggested that the SGO-TiO2-PAni catalyst could be applied as a potential alternative to the commercial Pt/C cathode catalyst for the application of MFCs.