兴奋剂
带隙
密度泛函理论
电子结构
费米能级
掺杂剂
分析化学(期刊)
金属
态密度
电子能带结构
作者
Wugen Huang,Jun Cai,Jun Hu,Junfa Zhu,Fan Yang,Xinhe Bao
出处
期刊:Chinese Journal of Catalysis
[China Science Publishing & Media Ltd.]
日期:2021-06-01
卷期号:42 (6): 971-979
被引量:2
标识
DOI:10.1016/s1872-2067(20)63710-x
摘要
Abstract An integrated approach combining scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS) is used to investigate the atomic structures and electronic properties of Cr-doped ZnO( ) surfaces. When deposited at 300 K, Cr at low surface coverage (l 0.1 ML) appeared either as isolated atoms on the surface terrace of ZnO( ) or substituting Zn atoms in the ZnO lattice. Their structural models could be identified from atomic-resolution STM images and their oxidation states were found as Cr3+ based on XPS measurements. Rectangular islands nucleated at step edges along the [0001] direction could also be observed during the initial growth of Cr at 300 K and were assigned as Cr islands. The density of Cr islands as well as their average size increased with the increasing of Cr surface loading. Thermal treatments at above 600 K could facilitate the decomposition of Cr islands and the re-dispersion of Cr atoms into the ZnO lattice, indicating a strong interaction between Cr and ZnO. The adsorption of CO at 78 K showed no preferential adsorption at Cr3+ sites embedded in the surface lattice of ZnO. However, the re-dispersion of Cr atoms into the ZnO bulk at above 600 K could induce a significant upward band bending, causing a negative shift of core level XPS peaks of Zn 2p and O 1s by ~0.5–0.7 eV. Our study has thus constructed a model catalyst for Cr-doped ZnO and provided atomic insight for understanding ZnO-based catalysts.
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