β-AgAl1-xGaxO2 Solid-Solution Photocatalysts: Continuous Modulation of Electronic Structure toward High-Performance Visible-Light Photoactivity
β-AgAl1-xGaxO2 Solid-Solution Photocatalysts: Continuous Modulation of Electronic Structure toward High-Performance Visible-Light Photoactivity
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DOI：
10.1021/ja110691t
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发表时间：
2011-05-25
影响因子：
15
通讯作者：
Ye, Jinhua
中科院分区：
文献类型：
--
作者：
Ouyang, Shuxin;Ye, Jinhua
探索了一系列β-AgAl 1-xGaxO 2固溶体材料作为新型可见光敏感光催化剂。这些Ag基固溶体结晶在一个均匀的晶体结构与正交对称的，但具有连续调制的带隙从2.19至2.83 eV，通过降低Ga/Al的比例。他们的异丙醇降解的光活性被发现是依赖于化学组成的变化。其中，β-AgAl 0. 6 Ga 0. 4 O2的光催化活性最高，分别是β-AgAl O2和β-AgGa O2的35倍和63倍。该样品在425 +/- 12 nm波长处对异丙醇光降解的表观量子效率达到37.3%。基于密度泛函理论的理论计算表明，β-AgAl 1-xGaxO 2的价带顶能级相似，但导带底能级随着Ga/Al比的增加而逐渐负移，从而使带隙不断变窄。然而，在β-AgAl 0. 6 Ga 0. 4 O2上观察到的最高活性可能归因于其优化的能带结构，其适应了有效可见光吸收和足够的氧化还原电位之间的平衡。
A series of beta-AgAl1-xGaxO2 solid-solution materials were explored as novel visible-light-sensitive photocatalysts. These Ag-based solid solutions crystallize in a homogeneous crystal structure with orthorhombic symmetry but possess continuously modulated band gaps from 2.19 to 2.83 eV by decreasing the ratios of Ga/Al. Their photoactivities for iso-propanol degradation were found to be dependent on the variation of chemical compositions. Among them, the beta-AgAl0.6Ga0.4O2 sample showed the highest photocatalytic performance, which simultaneously exhibited 35 and 63 times higher activities than two terminus materials, beta-AgAlO2 and beta-AgGaO2, respectively. The apparent quantum efficiency of this sample for iso-propanol photodegradation achieved up to 37.3% at the wavelength of 425 +/- 12 nm. The theoretical calculation based on density functional theory demonstrated that the levels of valence band maximum of beta-AgAl1-xGaxO2 are similar, but the levels of conduction band minimum are gradually negatively shifted with the increase of the ratio of Ga/Al, thereby continuously narrowing the band gap. Nevertheless, the highest activity observed on beta-AgAl0.6Ga0.4O2 may be attributed to its optimized band structure, which adapts the balance between effective visible-light absorption and adequate redox potentials.