Surface modification enhances the bulk proton conductivity of Prussian blue.

Surface-modified Prussian blue shows 10 2 times higher bulk proton conductivity (0.018 S cm -1 ) than that of unmodified Prussian blue. This enhancement is attributed to the monolayer adsorption of Na 4 [Fe(CN) 6 ] on the nanoparticle surface, which reduces the surface resistance. Surface modification is an effective strategy for improving bulk proton conductivity.