Pyrolyzed titanium dioxide/polyaniline as an efficient non-noble metal electrocatalyst for oxygen reduction reaction

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.