Synergetic defects boost charge separation in CN for enhanced photocatalytic water splitting
Synergetic defects boost charge separation in CN for enhanced photocatalytic water splitting
复制标题
协同缺陷促进 CN 中的电荷分离，增强光催化水分解
DOI：
10.1039/d0tc01479f
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发表时间：
2020-07-21
影响因子：
6.4
通讯作者：
Zhang, Jian
中科院分区：
文献类型：
--
作者：
Chi, Hualin;Liu, Jiaxi;Zhang, Jian
已证明，石墨碳（CN）的缺陷工程能够使能量水平对齐，以增强光催化H（2）进化（PHE）。由于结构不完善的CN中的大多数缺陷，“本地”缺陷至关重要，但它们在PHE中的作用仍然缺乏深入的理解。在这项工作中，通过聚合的热力学气氛控制制备了氮空位，羟基或氮空位和羟基共修饰的CN。发现氮空位和羟基共修饰的CN的氢生产速率约为2253.6 Mu mol H（-1）G（-1），约为氮酸率或羟基修饰的CN的PHE速率的3.0倍。进一步的瞬态光电流，电化学阻抗光谱和瞬时PL表征证实了两种缺陷在共同修饰的CN中的协同作用增强的光生电子孔分离。结合密度函数理论的计算，我们揭示了氮空位和羟基引入的宿主材料VBM和CBM附近的间隙状态的共同修饰，而可以通过单个CN形成深层陷阱状态，而由单个CN形成。氮空位或羟基的缺陷。
Defect engineering of graphitic carbon nitride (CN) has been proved to enable the alignment of energy levels for enhanced photocatalytic H(2)evolution (PHE). As the majority of defects in imperfect structured CN, "native" defects are critical but their role in PHE still lacks in-depth understanding. In this work, nitrogen vacancy, hydroxyl or nitrogen vacancy and hydroxyl co-modified CN was prepared by thermodynamic atmosphere control of the polymerization. It was found that the hydrogen production rate of nitrogen vacancy and hydroxyl co-modified CN is about 2253.6 mu mol h(-1)g(-1), about 3.0 times the PHE rate of either nitrogen vacancy or hydroxyl modified CN. Further transient photocurrent, electrochemical impedance spectroscopy and transient PL characterization confirmed the enhanced photogenerated electron-hole separation by the synergetic effects of the two defects in co-modified CN. In combination with density functional theory calculations, we revealed that co-modification of nitrogen vacancy and hydroxyl introduced gap states in the vicinity of the VBM and CBM of the host material, respectively, while deep trap states can be formed for CN modified by a single-type defect of nitrogen vacancy or hydroxyl.