The effect of water on the structural, electronic and photocatalytic properties of graphitic carbon nitride.
The effect of water on the structural, electronic and photocatalytic properties of graphitic carbon nitride.
复制标题
DOI：
10.1039/c3cp54333a
复制
发表时间：
2014-01
期刊：
影响因子：
--
通讯作者：
Hong-Zhang Wu;Li‐Min Liu;Shi-jin Zhao
中科院分区：
文献类型：
--
作者：
Hong-Zhang Wu;Li‐Min Liu;Shi-jin Zhao
g-C_3 N_4作为一种典型的无金属水裂解催化剂，引起了人们的广泛关注。水在g-C3 N4上吸附的结构和电子性质在理解原子水平上的水裂解机制中起着关键作用。采用密度泛函理论（DFT）方法研究了单片g-C3 N4的性质和单片g-C3 N4对水的吸附。结果表明，水分子吸附在单层g-C3 N4的一侧会导致其初始的平面结构向屈曲结构转变，而水分子吸附在g-C3 N4的两侧不会影响其平面结构.平板状的g-C_3 N_4是一种间接半导体，有趣的是，在从平板到屈曲的转变过程中，由于水的吸附，g-C_3 N_4的能带结构发生了由间接到直接的变化。在低覆盖度下，水分子优先吸附在单层g-C3 N4的本征空位周围，进一步吸附的水分子停留在本征空位周围。水吸附也影响g-C3 N4的带边位置用于水裂解。这些结果为深入了解g-C3 N4的结构和在水环境中的吸附性质提供了理论依据，有助于设计新型无金属水裂解催化剂。
g-C3N4, as a typical metal-free catalyst for water splitting, has attracted special attention. The structural and electronic properties of water adsorption on g-C3N4 play a key role in understanding the water splitting mechanism at the atomic level. The properties of a single g-C3N4 sheet and the water adsorption on a single g-C3N4 sheet were thoroughly explored based on density functional theory (DFT) calculations. The results show that water adsorption on one side of the single g-C3N4 sheet will lead the initial flat structure to change to a buckle one, while water molecule adsorption on both sides of g-C3N4 will not disturb the flat structure. The flat g-C3N4 is an indirect semiconductor, and interestingly the band structure of g-C3N4 changes from an indirect to a direct one during the flat structure transformation from flat to buckle because of the water adsorption. Water molecules prefer to adsorb around the intrinsic vacancy of the single g-C3N4 sheet at low coverage, and further adsorbed water molecules stay around the intrinsic vacancy. Water adsorption also affects the band edge position of g-C3N4 for water splitting. These results provide a deep insight into the structure and adsorption properties of g-C3N4 in the water environment, which will greatly help to design a new type of metal-free catalyst for water-splitting.