Huang Fei, Ning Jiajia, Xiong Wei, Shen Ting, Zhao Yanling, Tian Jianjun, Zhang Ruiqin, Rogach Andrey L
Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, China.
Department of Physics, City University of Hong Kong, Hong Kong 999077, China.
Nanomaterials (Basel). 2020 May 31;10(6):1081. doi: 10.3390/nano10061081.
We introduced atomic sulfur passivation to tune the surface sites of heavy metal-free ZnSe nanorods, with a Zn-rich termination surface, which are initially capped with organic ligands and under-coordinated with Se. The S ions from a sodium sulfide solution were used to partially substitute a 3-mercaptopropionic acid ligand, and to combine with under-coordinated Zn termination atoms to form a ZnS monolayer on the ZnSe surface. This treatment removed the surface traps from the ZnSe nanorods, and passivated defects formed during the previous ligand exchange process, without sacrificing the efficient hole transfer. As a result, without using any co-catalysts, the atomic sulfur passivation increased the photocurrent density of TiO/ZnSe photoanodes from 273 to 325 μA/cm. Notably, without using any sacrificial agents, the photocurrent density for sulfur-passivated TiO/ZnSe nanorod-based photoanodes remained at almost 100% of its initial value after 300 s of continuous operation, while for the post-deposited ZnS passivation layer, or those based on ZnSe/ZnS core-shell nanorods, it declined by 28% and 25%, respectively. This work highlights the advantages of the proper passivation of II-VI semiconductor nanocrystals as an efficient approach to tackle the efficient charge transfer and stability of photoelectrochemical cells based thereon.
我们引入了原子硫钝化来调节富含锌的终止表面的无重金属ZnSe纳米棒的表面位点，这些纳米棒最初被有机配体包覆且硒原子配位不足。来自硫化钠溶液的硫离子用于部分替代3-巯基丙酸配体，并与配位不足的锌终止原子结合，在ZnSe表面形成ZnS单层。这种处理消除了ZnSe纳米棒的表面陷阱，并钝化了先前配体交换过程中形成的缺陷，同时不牺牲有效的空穴转移。结果，在不使用任何助催化剂的情况下，原子硫钝化使TiO/ZnSe光阳极的光电流密度从273增加到325 μA/cm²。值得注意的是，在不使用任何牺牲剂的情况下，基于硫钝化的TiO/ZnSe纳米棒的光阳极在连续运行300秒后的光电流密度几乎保持在其初始值的100%，而对于后沉积的ZnS钝化层或基于ZnSe/ZnS核壳纳米棒的光阳极，其光电流密度分别下降了28%和25%。这项工作突出了对II-VI族半导体纳米晶体进行适当钝化作为解决基于其的光电化学电池有效电荷转移和稳定性的有效方法的优势。
