Mussel-inspired fabrication of a flexible free-standing membrane cathode for oxygen reduction in neutral media

In this paper, we present a flexible free-standing membrane cathode fabricated via the electroless metallization of bacterial cellulose (BC) by polydopamine (PDA) and silver nanoparticles. A BC/PDA composite membrane was synthesized by the self-assembly of PDA on the nanofibers of BC. The membrane was electrolessly metalized by reducing silver ions with the reducing groups present in PDA. The resulted membrane was flexible and had good mechanical property. The conductivity of the membrane was measured to be 2.72 +/- 0.13 s/cm. SEM showed that PDA formed a uniform coating on the nanofibers of BC, and that silver nanoparticles (Ag NPs) were uniformly and densely decorated on the PDA coated BC fibers. Cyclic voltammetry showed that the membrane electrode had good electrocatalytic activities towards oxygen reduction reaction (ORR) in neutral phosphate buffer solution (PBS). Furthermore, the BC/PDA/Ag electrode was insensitive to glucose and exhibited good cycling stability. Polarization curves revealed that BC/PDA/Ag had good cathode performance. The synthesized membrane cathode shows potential in implantable, microbial and flexible fuel cells.