Synthesis of tungstate oxide/bismuth tungstate composite and application in microbial fuel cell as superior low-cost cathode catalyst than platinum

Low cost tungsten oxide/bismuth tungstate (WO₃/Bi₂WO₆) composite was synthesized and used as cathode catalyst in microbial fuel cell (MFC). Almost 1.5 times increment in specific surface area of WO₃/Bi₂WO₆ composite was observed as compared with WO₃ and WO₃/Bi₂WO₆ exhibited efficient oxygen reduction reaction (ORR) having a current peak of 8.1 mA at – 12.6 mV during cyclic voltammetry analysis, demonstrating less ORR overpotential. The MFC using WO₃/Bi₂WO₆ catalysed cathode could recover a power density (PD) of 145 ± 4.5 mW/m² and coulombic efficiency (CE) of 28.3 ± 1.5%, followed by 35 ± 5.8 mW/m² and 17.5 ± 2.4%, respectively, for MFC with WO₃ catalyzed cathode and 10.4 ± 3.2 mW/m² and 10.3 ± 0.9%, respectively, for MFC without any cathode catalyst. Moreover, the PD and CE of 138 ± 6.8 mW/m² and 27.5 ± 2.0%, respectively, obtained from MFC using Pt/C cathode catalyst, was slightly lower than the MFC with WO₃/Bi₂WO₆ catalyst on cathode. The specific power recovery per unit cost of cathode fabrication of 23.8 mW/$ obtained from MFC with WO₃/Bi₂WO₆ catalyzed cathode is higher than the MFC with Pt/C (12.2 mW/$), making it low cost alternative for scaling-up of MFCs.