Introduction.- Carbon nanotube enhanced microbial anode catalysis.- Immobilized redox mediator regulated microbial anode catalysis.- Nano-structured manganese oxide enhanced oxygen reduction as a cathodic catalyst.- Nano-structed Ag catalyzed the cathodic reduction of p-notrophenol.- Photoautotrophic cathodic oxygen reduction catalyzed by a green alga.- Integration of a biocathode microbial fuel cell with activated sludge process for energy-saving wastewater treatment.- Summary.