Is platinum-loaded titania the best material for dye-sensitized hydrogen evolution under visible light?

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(I_(3)-),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 I_(3)-,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.

发射光谱法

美国分析化学(Anal.Chem.)杂志每两年分专题发表一次基础述评(Fund.Rev),比较全面地总结了两年来在本专题范围内所获得的最新成就,信息量极为丰富,这对分析测试工作者了解世界发展动态,很有参考价值——可以说,读了它基本上可以起到'秀才不出门,全知天下事'的作用。为此,我们从第5卷第2辑起,选登有关光谱、能谱分析几个专题的译文,并同时附上参考文献,以便读者查找。所选专题是:拉曼光谱学,分子荧光、磷光和化学发光光谱法,X射线光谱法,表面分析;X射线光电子能谱学和俄歇电子能谱学,紫外光及可见光吸收光谱法,发射光谱法,原子吸收、原子荧光和火焰发射光法,穆斯谱堡尔能谱学等。