Metallic Co9S8 Coupled Hollow N-Doped Carbon Sphere with Synergistic Interface Structure for Efficient Electricity Generation in Microbial Fuel Cells

The high cost, low abundance and poor durability of precious metal catalysts greatly hinder the practical applications of microbial fuel cells (MFCs) for bioremediation and bioelectricity generation. It is imperative to develop highly efficient and robust noble metal-free catalysts for the high power density of MFCs. In this work, we present a scalable and cost-effective strategy to synthesize Co9S8 nanoparticles coupled with nitrogen-doped hollow carbon sphere (NHCS), which subtly constructs synergistic interface structures that expose plentiful active sites and afford high conductive channel for charge transfer. The as-obtained porous Co9S8/NHCS exhibits excellent catalytic activity, and superior stability as well as methanol tolerance during oxygen reduction reaction (ORR) process in both alkaline and neutral environment. The MFC device equipped with Co9S8/NHCS as air-cathode achieves a remarkable power density of 704 +/- 22 mW m(-2) and outstanding chemical oxygen demand (COD) removal rate of 96.28 %+/- 0.50 %, which is even superior to the performance of commercial Pt/C catalyst. The favorable results provide a new concept to design and explore porous noble metal-free electrocatalysts for clean and sustainable energy conversion.