Graphene-supported silver nanoparticles for pH-neutral electrocatalytic oxygen reduction

In order to improve the electrocatalysis of oxygen reduction and reduce the captive cost of microbial fuel cell (MFC), graphene-supported catalyst of silver nanoparticles (Ag/RG) was prepared and its activity toward oxygen reduction reaction (ORR) in pH-neutral condition was examined. The Ag/RG catalyst was prepared by chemical reduction of aqueous silver ions to silver nanoparticles on the surface of reduced graphene (RG), which was obtained from graphene oxide (GO) precursor synthesized via classic Hummer´s method using graphite as starting material. The results demonstrated that aqueous co-reduction method could yield high-quality Ag/RG catalyst, in which Ag nanoparticles were dispersed on the graphene surface with average diameter of 13 nm as revealed by XRD and TEM examination. The XPS results suggested the presence of polar oxygen-containing functional groups on the graphene sheets could provide the nuclei to form Ag nano-structure. The CV results showed that Ag/RG was active of catalyzing ORR electrochemically in pH-neutral electrolyte. Since Ag costs much less than Pt, Ag/RG is expected to hold remarkable potential as a promising alternative to promote the commercialization of MFC for practical application.