We present a strategy to prepare a highly active Au/ZnO catalyst for CO oxidation by introducing abundant Zn- and O-vacancy defects into a ZnO support of mesocrystal form. Two different ZnO supports were chosen for comparison; almost defect-free ZnO nanorods (NR-ZnO) and twin-brush-like ZnO mesocrystals (TB-ZnO) with rich Zn/O-vacancy defects gave Au/NR-ZnO and Au/TB-ZnO upon deposition of gold nanoparticles. The catalytic test of CO oxidation over Au/TB-ZnO catalyst showed an enhanced catalytic activity that was 153 times greater than the activity of Au/NR-ZnO. The dramatic enhancement in CO oxidation is attributed to a room-temperature Mars–van Krevelen (MvK) mechanism on the surface of the Au/TB-ZnO catalyst, which was promoted by extensive vacancy defects in TB-ZnO. To elucidate the increase in activity, the vacancy ratio (i.e., [V_O^•]/[V_Zn^•]) of TB-ZnO was systematically modulated by adjusting calcination conditions. The defective ZnO support altered the tendency in the variation of size, valence state, and activity of gold correlated to an increased vacancy ratio. Combining experimental results and theoretical modeling, it is concluded that the higher vacancy ratio [V_O^•]/[V_Zn^•] in support endows defective ZnO with accommodation of plenty of “Au–O–Au_Zn” linkages (Au_Zn denotes Au substitution at a Zn site) around gold nanoparticles. The O atom extraction from “Au–O–Au_Zn” linkages formed by gold doping in ZnO lattice is energetically more favorable than typical “Au–O–Zn” linkages at the perimeter of gold, facilitating CO oxidation via MvK mechanism. Systematic manipulation of defects density in the support provides a method in improving catalytic properties of supported gold catalysts.

中文翻译：

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缺陷的介晶ZnO负载金催化剂：通过ZnO中的空位缺陷促进CO氧化

我们提出了一种通过将大量的Zn和O空位缺陷引入介晶形式的ZnO载体中来制备用于CO氧化的高活性Au / ZnO催化剂的策略。选择了两种不同的ZnO载体进行比较。几乎无缺陷的ZnO纳米棒（NR-ZnO）和具有丰富Zn / O空位缺陷的双刷状ZnO介晶（TB-ZnO）在金纳米颗粒沉积时得到Au / NR-ZnO和Au / TB-ZnO。在Au / TB-ZnO催化剂上进行CO氧化的催化测试显示出增强的催化活性，是Au / NR-ZnO活性的153倍。CO氧化的显着增强归因于Au / TB-ZnO催化剂表面的室温Mars-van Krevelen（MvK）机理，这是由于TB-ZnO中大量的空位缺陷所致。为了阐明活动的增加，空缺率（即[V通过调节煅烧条件，系统地调节了TB-ZnO的_O ^• ] / [V _Zn ^• ]）。有缺陷的ZnO载体改变了尺寸，价态和金活性与空位比增加相关的变化趋势。结合实验结果和理论模型，得出的结论是，载体中较高的空位比[V _O ^• ] / [V _Zn ^• ]赋予缺陷ZnO大量“ Au–O–Au _Zn ”键（Au _Zn表示Au）。在金纳米粒子周围的Zn位置进行取代）。从“ Au–O–Au _Zn ”中提取O原子ZnO晶格中金掺杂形成的键在能量上比金周边的典型“ Au–O–Zn”键更有利，这有利于通过MvK机理进行CO氧化。载体中缺陷密度的系统操作提供了一种改善载体金催化剂的催化性能的方法。