Effect of fiber diameter on the behavior of biofilm and anodic performance of fiber electrodes in microbial fuel cells

► Simple fixation and dehydration method is applied on biofilms and original biofilm morphology in fiber anode is obtained. ► The morphologies of biofilms in anodes are changed from porous to continuous solid with fiber size decreasing to ∼1 μm. ► The current density generated by the continuous solid biofilms increases linearly with increase of biofilm thickness. ► Fiber anode with fiber diameter around the size of the dominant microorganisms generates the highest current density.