A Stable, Narrow-Gap Oxyfluoride Photocatalyst for Visible-Light Hydrogen Evolution and Carbon Dioxide Reduction
A Stable, Narrow-Gap Oxyfluoride Photocatalyst for Visible-Light Hydrogen Evolution and Carbon Dioxide Reduction
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DOI：
10.1021/jacs.8b02822
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发表时间：
2018-05-30
影响因子：
15
通讯作者：
Maeda, Kazuhiko
中科院分区：
文献类型：
--
作者：
Kuriki, Ryo;Ichibha, Tom;Maeda, Kazuhiko
氮氧化物和硫族化合物等混合阴离子化合物被认为是可见光驱动光催化剂的潜在候选者，因为与氧2p轨道相比，电负性较小的阴离子（例如N3-、S2-）的p轨道可以形成具有更多负电势的价带。在这方面，氟氧化物似乎不合适，因为氟的电负性较高。在这里，我们展示了一个例外的情况，即阴离子有序的烧绿石氟氧化物 Pb2Ti2O5.4F1.2，它具有小带隙（约 2.4 eV）。通过铂纳米颗粒和双核钌(II)络合物等促进剂对 Pb2Ti2O5.4F1.2 进行适当修饰，Pb2Ti2O5.F-4(1.2) 可作为稳定的光催化剂，用于可见光驱动的 H-2 析出和 CO2 还原。密度泛函理论计算表明，Pb2Ti2O5.F-4(1.2)前所未有的可见光响应源于Pb-6s和O-2p轨道之间的强相互作用，这是由于氟取代而导致烧绿石晶格中的短Pb-O键实现的。
Mixed anion compounds such as oxynitrides and oxychalcogenides are recognized as potential candidates of visible-light-driven photocatalysts since, as compared with oxygen 2p orbitals, p orbitals of less electronegative anion (e.g., N3-, S2-) can form a valence band that has more negative potential. In this regard, oxyfluorides appear unsuitable because of the higher electronegativity of fluorine. Here we show an exceptional case, an anion-ordered pyrochlore oxyfluoride Pb2Ti2O5.4F1.2 that has a small band gap (ca. 2.4 eV). With suitable modification of Pb2Ti2O5.4F1.2 by promoters such as platinum nanoparticles and a binuclear ruthenium(II) complex, Pb2Ti2O5.F-4(1.2) worked as a stable photocatalyst for visible-light-driven H-2 evolution and CO2 reduction. Density functional theory calculations have revealed that the unprecedented visible-light-response of Pb2Ti2O5.F-4(1.2) arises from strong interaction between Pb-6s and O-2p orbitals, which is enabled by a short Pb-O bond in the pyrochlore lattice due to the fluorine substitution.