Macroporous spider net-like NiO nanowire on carbon nanowire to grow a biofilm with multi-layered bacterium cells toward high-power microbial fuel cells

An in-situ deposition of a spider net-like NiO nanowires onto a nitrogen-doped carbon nanowire forming a macroporous network on carbon cloth (NiO@N-CNWs/CC) is a new facile approach to fabricate a substrate on which Shewanella Putrefaciens grows. The NiO@N-CNWs/CC associated with biofilm is a multi-layers of bacterium cells on a conductive current collector, which significantly boosts the power density higher than that of carbon cloth by 8.5 times, even though it is typically very difficult to grow a thick biofilm with high biocatalyst to raise the relatively low power density usually found in microbial fuel cells (MFCs). The NiO nanowires play a bifunctional role in promoting the high power density of NiO@N-CNWs/CC MFCs: 1) such a macroporous surface anchors the first layer of bacterium cells tightly, and allows more layers of cells growing on its top for a thick film, 2) the very conductive NiO nanowires network enables the fast electron transfer/transport through the thick biofilm for achieving the high power density.