Unique Electronic Structure Induced High Photoreactivity of Sulfur-Doped Graphitic C3N4
Unique Electronic Structure Induced High Photoreactivity of Sulfur-Doped Graphitic C3N4
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DOI：
10.1021/ja103798k
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发表时间：
2010-08-25
影响因子：
15
通讯作者：
Cheng, Hui-Ming
中科院分区：
文献类型：
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作者：
Liu, Gang;Niu, Ping;Cheng, Hui-Ming
电子结构本质上控制着半导体光催化剂的吸光度、氧化还原电位、电荷载流子迁移率，并因此控制其光反应性。通过阴离子掺杂改变半导体光催化剂的电子结构以获得更宽的吸收范围的常规方法以降低的氧化还原电位和/或电荷载流子迁移率为代价进行操作，使得其光反应性通常受到限制，并且一些重要的反应可能根本不发生。在这里，我们报告硫掺杂的石墨C3 N4（C3 N4-xSx）具有独特的电子结构，其显示出增加的价带宽与升高的导带最小值和略微降低的吸光度相结合。在λ> 300和420 nm下，C3 N4-xSx的光反应性分别是C3 N4的7.2和8.0倍。更引人注目的是，对于硫掺杂的C3 N4，苯酚在λ> 400 nm下可以发生完全氧化过程，这对于C3 N4甚至在λ> 300 nm下也是不可能的。硫的晶格氮的均匀取代和伴随的量子限制效应被确定为这种独特的电子结构的原因，因此，优异的光反应性的C3 N4-xSx。所获得的结果可能揭示了设计潜在的高效光催化剂的一般掺杂策略。
Electronic structure intrinsically controls the light absorbance, redox potential, charge-carrier mobility, and consequently, photoreactivity of semiconductor photocatalysts. The conventional approach of modifying the electronic structure of a semiconductor photocatalyst for a wider absorption range by anion doping operates at the cost of reduced redox potentials and/or charge-carrier mobility, so that its photoreactivity is usually limited and some important reactions may not occur at all. Here, we report sulfur-doped graphitic C3N4 (C3N4-xSx) with a unique electronic structure that displays an increased valence bandwidth in combination with an elevated conduction band minimum and a slightly reduced absorbance. The C3N4-xSx shows a photoreactivity of H-2 evolution 7.2 and 8.0 times higher than C3N4 under lambda > 300 and 420 nm, respectively. More strikingly, the complete oxidation process of phenol under lambda > 400 nm can occur for sulfur-doped C3N4, which is impossible for C3N4 even under lambda > 300 nm. The homogeneous substitution of sulfur for lattice nitrogen and a concomitant quantum confinement effect are identified as the cause of this unique electronic structure and, consequently, the excellent photoreactivity of C3N4-xSx. The results acquired may shed light on general doping strategies for designing potentially efficient photocatalysts.