Photophysical and photocatalytic properties of a new series of visible-light-driven photocatalysts M3V2O8 (M = Mg, Ni, Zn)
Photophysical and photocatalytic properties of a new series of visible-light-driven photocatalysts M3V2O8 (M = Mg, Ni, Zn)
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DOI：
10.1021/cm051016x
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发表时间：
2005-10-04
影响因子：
8.6
通讯作者：
Ye, JH
中科院分区：
文献类型：
--
作者：
Wang, DF;Tang, JW;Ye, JH
采用传统的固相反应法合成了一系列可见光催化剂M3 V2 O 8（M = Mg，Ni，Zn）。采用X射线粉末衍射和紫外-可见漫反射光谱分别表征了其晶体结构和物理性能。通过在可见光照射下AgNO 3水溶液中的O-2释放来评价光催化性能。结果表明，M3 V2 O 8（M = Mg，Ni，Zn）3种化合物均为正交晶系，空间群为Abam。然而，不同电子状态的M2+阳离子的取代对其物理和光催化性能产生显著影响。Zn_3V_2O_8的活性高于Mg_3V_2O_8，而Ni_3V_2O_8几乎没有活性。采用平面波密度泛函理论（DFT）对M3 V1 O 8（M = Mg，Ni，Zn）的能带结构和态密度进行了理论计算，结果表明，M3 V1 O 8（M = Mg，Ni，Zn）不同的电子结构导致了其不同的物理性质和光催化性能. Zn 3V 2 O 8的3d和O2 p轨道杂化，形成价带，有利于光激发空穴在价带中的迁移，从而提高了O-2的释放活性。与此相反，没有这样的杂化效应发生在Mg3 V2 O 8的Mg 2 p轨道不参与价带。Ni 3V 2 O 8中插入O 2 p和V 3d轨道之间的分裂Ni 3d轨道不适合O-2的演化。
A new series of visible-light-driven photocatalysts M3V2O8 (M = Mg, Ni, Zn) was synthesized by theconventional solid-state reaction method. The crystal structure and photophysical properties were characterized by powder X-ray diffraction and UV-vis diffuse reflectance spectroscopy, respectively. Photocatalytic properties were evaluated by O-2 evolution from an aqueous AgNO3 solution under visible light irradiation. The results showed that the three compounds of M3V2O8 (M = Mg, Ni, Zn) were all crystallized in an orthorhombic system with the space group Abam. However, the substitution of M2+ cations with different electronic states imposed significant effects on their photophysical and photocatalytic properties. Zn3V2O8 showed a higher activity than Mg3V2O8, while Ni3V2O8 showed almost no activity. Theoretically calculated energy band structures and density of states (DOS) by the plane-wave-density function theory (DFT) revealed that the different photophysical and photocatalytic properties of M3V1O8 (M = Mg, Ni, Zn) could be ascribed to their different electronic structures. The Zn 3d and O 2p orbitals were hybridized to construct the valence band of Zn3V2O8, favoring the mobility of photoexcited holes in the valence band and thus promoting the O-2 evolution activity. In contrast, no such hybridization effect occurs in Mg3V2O8 as the Mg 2p orbitals are not involved in the valence band. The split Ni 3d orbitals inserted between the O 2p and the V 3d orbitals in Ni3V2O8 are not suitable for O-2 evolution.