Kinetics Of Highly Efficient Visible Light-induced Ag(â… )-catalyzed Water Oxidation Into Dioxygen

Kinetics and mechanism of water oxidation into dioxygen is particularly significant forunderstanding photosystem â… â…  photosynthesis and developing a viable water oxidation catalyst.â… n this paper, using S₂O₈^2-as an oxidant and Ag⁺as a catalyst, kinetics and mechanism ofvisible light-induced water oxidation into dioxygen is investigated. We found using S₂O₈^2-asan oxidant, Ag⁺is a favorable catalyst in common inorganic salts. Visible light can accelerateAg⁺-catalyzed water oxidation of S₂O₈^2-into O₂in the system of Ag⁺-S₂O₈^2-. O₂is producedaccording to a first-order law with the concentration of S₂O₈^2-ion. The rate equation isfollowed:-dc(S₂O₈^2-)/dt=2dc（O₂）/dt=kc(S₂O₈^2-)The rate constant （k） values at4.5,11.5,17.5and24.5oC are5.5，8.8，11.8，16.2respectively.Comparing to the O₂evolution rates under no light irradiation, those under the visible lightillumination may not depend on temperatures. The result illustrates that visible light canaccelerate O₂evolution in the system of Ag⁺-S₂O₈^2-. Meanwhile, we understand themechanism of O₂evolution in the system of Ag⁺-S₂O₈^2-better by ESR et al technology.Based on our research group, the stability of Na9H5[Co₂Bi₂(α-Î'-CoW₉O₃₄)₂]·58H2O1and Na14[Co₂Bi₂(β-Î'-CoW₉O₃₄)₂]·48H2O2in water is investigated. â… t is proved that1isstable in the solution by linear sweep voltammetry.