Novel Multinuclear Catalysts for the Electroreduction of Dioxygen Directly to Water

摘要: The electroreduction of O_2 to H_2O in aqueous acid at potentials close the thermodynamically permitted value remains a daunting challenge for designers superior fuel cells and batteries that utilize dioxygen as reducible reactant. four-electron reduction O_2, which involves the rupture O-O bond formation four O-H bonds, requires use catalysts obtain useful rates at cathode potentials interest practical applications. standard potential O_2/H_2O couple solutions containing 1 M H^+ saturated with at 1 atm is ca. 1.0 V (vs calomel electrode, SCE), but highest achievable currently available are closer 0.55 V. (Molecules, functional groups, or metallic deposits accelerate electrode reactions when they confined surfaces electrodes often called electrocatalysts, terminology will be adopted this Account.) Finely divided platinum supported on high area carbon electrocatalyst employed most frequently achieve presently fuel cells. However, type suffers from disadvantages cost gradual loss catalytic activity surface active particles decreases because sintering, dissolution, physical dislodgment, and/or adsorption impurities. Searches electrocatalysts O2 have focused cobalt porphyrins well-known exhibit electrocatalytic toward although H_2O_2 instead usual product. it was discovered recent years variety molecular consisting dimeric cofacial adsorbed graphite able catalyze direct without passing through an intermediate. Both monomeric iridium por phyrins also been found accomplish unusually positive potentials. mechanisms believed operate involve simultaneous interaction both metal centers two oxygen atoms molecule severed. ideas strategies underlay the development these described.