A dye-sensitized photocatalyst combining Pt-loaded TiO_(2)and Ru(Ⅱ)tris-diimine sensitizer(RuP)was constructed and its activity for photochemical hydrogen evolution was compared with that of Pt-intercalated HCa_(2)Nb...A dye-sensitized photocatalyst combining Pt-loaded TiO_(2)and Ru(Ⅱ)tris-diimine sensitizer(RuP)was constructed and its activity for photochemical hydrogen evolution was compared with that of Pt-intercalated HCa_(2)Nb_(3)O_(10)nanosheets.When the sacrificial donor ethylenediaminetetraacetic acid(EDTA)disodium salt dihydrate was used,RuP/Pt/TiO_(2)showed higher activity than RuP/Pt/HCa_(2)Nb_(3)O_(10).In contrast,when NaI(a reversible electron donor)was used,RuP/Pt/TiO_(2)showed little activity due to back electron transfer to the electron acceptor(I3-),which was gener-ated as the oxidation product of I-.By modification with anionic polymers(sodium poly(styrenesulfonate)or sodium polymethacrylate)that could inhibit the scavenging of conduction band electrons by I3-,the H_(2)production activity from aqueous NaI was improved,but it did not exceed that of RuP/Pt/HCa_(2)Nb_(3)O_(10).Transient absorption measurements showed that the rate of semiconductor-to-dye back electron transfer was slower in the case of TiO_(2)than HCa_(2)Nb_(3)O_(10),but the electron transfer reaction to I3-was much faster.These results indicate that Pt/TiO_(2)is useful for reactions with sacrificial reductants(e.g.,EDTA),where the back electron transfer reaction to the more reducible product can be neglected.However,more careful design of the catalyst will be nec-essary when a reversible electron donor is employed.展开更多
文摘A dye-sensitized photocatalyst combining Pt-loaded TiO_(2)and Ru(Ⅱ)tris-diimine sensitizer(RuP)was constructed and its activity for photochemical hydrogen evolution was compared with that of Pt-intercalated HCa_(2)Nb_(3)O_(10)nanosheets.When the sacrificial donor ethylenediaminetetraacetic acid(EDTA)disodium salt dihydrate was used,RuP/Pt/TiO_(2)showed higher activity than RuP/Pt/HCa_(2)Nb_(3)O_(10).In contrast,when NaI(a reversible electron donor)was used,RuP/Pt/TiO_(2)showed little activity due to back electron transfer to the electron acceptor(I3-),which was gener-ated as the oxidation product of I-.By modification with anionic polymers(sodium poly(styrenesulfonate)or sodium polymethacrylate)that could inhibit the scavenging of conduction band electrons by I3-,the H_(2)production activity from aqueous NaI was improved,but it did not exceed that of RuP/Pt/HCa_(2)Nb_(3)O_(10).Transient absorption measurements showed that the rate of semiconductor-to-dye back electron transfer was slower in the case of TiO_(2)than HCa_(2)Nb_(3)O_(10),but the electron transfer reaction to I3-was much faster.These results indicate that Pt/TiO_(2)is useful for reactions with sacrificial reductants(e.g.,EDTA),where the back electron transfer reaction to the more reducible product can be neglected.However,more careful design of the catalyst will be nec-essary when a reversible electron donor is employed.
