Electrophoretic deposition-assisted layer-by-layer construction of carbon nanotube-MnO2-based hybrid biofilm for supercapacitive microbial fuel cells.

The exploitation of hybrid biofilm with alternating functional layer represents a promising way to upgrade the performance of supercapacitive microbial fuel cells (SC-MFCs). However, the popularization of this special hybrid biofilm requires a convenient and scalable construction strategy. Herein, the electrophoretic deposition-assisted layer-by-layer construction strategy has been developed to successively deposit carbon nanotube-manganese dioxide nanocomposite (C-M) and bacterial cells for the formation of hybrid biofilm. When using in SC-MFCs, the hybrid biofilm with two repetitive C-M/bacteria bilayers displayed the optimal performance due to the improvement of functional components without the sacrifice of electron transfer efficiency and bacterial metabolic activity. Moreover, the intercalation of capacitive and conductive C-M layer between bacteria layers enlarges their interaction interface and builds an accelerated electron transfer network inside the developed hybrid biofilm. As a result, the developed hybrid biofilm displayed enhanced capacitance, improved electricity generation capacity and promoted self-charge-discharge behavior compared to the counterpart biofilms. This work demonstrates the potential of electrophoretic deposition technology for the alternative construction of different functional layers in hybrid biofilm, which will be attractive for SC-MFCs and other microbial electrochemical systems.