Cathodic electrochemiluminescence of tris(2,2′-bipyridine) ruthenium(II) on Ag nanoparticles-modified electrode

An interesting phenomenon that significant cathodic electrochemiluminescence of tris(2,2′-bipyridine)ruthenium(II) with assistance of metal nanoparticles (Ag, Cu) on Pt electrode was observed for the first time in acid buffer solution. This is different from that only anodic electrochemiluminescence occurs when bare Pt electrode is used. Both anodic and cathodic ECL peaks were found at 0.4   V with positive potential scan and 0   V with negative initial potential scan, respectively, in the presence of Ag. A possible mechanism was proposed that Ag might act as a co-reactant to ignite cathodic ECL of Ru ( bpy ) 3 2 + $\text{Ru}{(\text{bpy})}_3^{2+}$ system in low pH condition, which was similar to the result we observed previously in the case of Au. Considering high market price of Au, relatively cheaper metal Ag is more promising for potential application in ECL.