As an emerging technology, microbial fuel cell (MFC) can extract electricity from wastewater and has attracted much attention during the past couple years. While a plethora of recent studies reported electricity could be generated from MFCs using various easily degradable organics as fuels in the anode, the cost of cathode materials incorporating precious metals such as Pt is prohibitive to wide-scale implementation, and the unsustainable use of ferricyanide as a catalyst-independent cathode electrolyte is ...