Splitting of water by combining two photocatalytic reactions through a quinone compound dissolved in an oil phase

Two photocatalytic reactions producing oxygen and hydrogen, respectively, w ere combined using a quinone compound dissolved in an oil phase. As quinone compound, 3,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) was utilized, wh ich was dissolved in n-butyronitrile. When an oil phase containing the redu ced form of DDQ (DDHQ) was placed on an aqueous phase containing Pt-loaded TiO2, particles and bromide ions, hydrogen and bromine were produced in the aqueous phase by photoirradiation of the Pt-loaded TiO2, particles. The br omine then oxidized DDHQ in the oil phase. Similarly, by photoirradiation o f an aqueous solution containing TiO2, particles and iron(III) ions, oxygen and iron(II) ions were produced. When the reaction was carried out in the double phase system consisting of the aqueous phase and the oil phase conta ining DDQ, DDQ was reduced to DDHQ by the iron(II) ions. The results indica te the feasibility of water splitting by combining two photocatalytic react ions through redox reactions of a quinone compound.