Adsorption Properties of Keggin-type Polyoxometalates on Carbon Based Electrode Surfaces and Their Electrocatalytic Activities

The interactions between four Keggin-type POMS (SiW12O404-, PW12O403-, SiMo12O404-, and PMo12O403-) and glassy carbon (GC) and highly oriented pyrolytic graphite (HOPG) surfaces are investigated in a systematic way Electrochemical results show that molibdate series POMs adsorb relatively stronger than tungstate POMs on GC and HOPG surfaces. Adsorption of POMs on HOPG electrode surfaces is relatively stronger than on GC surfaces. SiMo12O404- species exhibits unique adsorption behaviors on HOPG surfaces. Surface-con fined SiMo12O404- species on HOPG surfaces exhibit unique adsorption behaviors and inhibit the electron transfer from the solution phase species. The catalytic activity of the surface-confined POMs for hydrogen peroxide electroreduction is also examined, where PW12O403- species adsorbed on GC surfaces exhibits the highest catalytic efficiency among the investigated POM modified electrode systems.