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首页> 外文期刊>The journal of physical chemistry, C. Nanomaterials and interfaces >Reduction of Nano-Cu2O: Crystallite Size Dependent and the Effect of Nano-Ceria Support
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Reduction of Nano-Cu2O: Crystallite Size Dependent and the Effect of Nano-Ceria Support

机译：纳米Cu2O的还原：晶粒尺寸依赖性和纳米二氧化铈载体的影响

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摘要

Copper(I) oxide (Cu2O) is an effective catalyst in the CO oxidation reaction. While high surface to volume ratio in nanoparticles will increase their catalytic efficiency, it posts a stability problem. Here we study the stability of nano-cuprite against reduction as a function of its crystallite size and upon interaction with a nano-ceria support. A systematic analysis of isothermal reduction of a series size of monodispersed Cu2O nanocrystals (+/- 7%) with time-resolved X-ray diffraction (TR-XRD) provides the time-resolved phase fraction of Cu2O and the time when reduction product of Cu (fcc) first appears. The initial phase fraction of nano-Cu2O is less than one with the balance attributed to an amorphous CuO shell. Since no peaks of crystalline CuO (monoclinic) were observed, a coreshell structure with an amorphous CuO shell is proposed. From the analysis, Cu2+ content in corresponding to shell increases from 0 to 33% as Cu2O decreases to 8 nm from the bulk. Based on the reduction profiles, a time size reduction (TSR) diagram is constructed for the observed Cu2O phase behavior during reduction. The incorporation onto a nano-CeO2 support (7 nm) significantly stabilizes our nano-Cu2O in a reducing atmosphere. The oxygen supply propensity in terms of oxygen nonstoichiometry of CeO2-y is shown to be lower when a larger crystallite size CeO2 (20 nm) support is used. The larger oxygen capacity in smaller nano-CeO2 support is analyzed and explained by the Madelung model with size-dependent bulk modulus of nano-ceria.
机译：氧化铜（I 2）是CO氧化反应中的有效催化剂。尽管纳米颗粒中高的表面体积比会提高其催化效率，但它会带来稳定性问题。在这里，我们研究了纳米亚铁酸盐抗还原的稳定性，该稳定性是其微晶尺寸以及与纳米二氧化铈载体相互作用的函数。用时间分辨X射线衍射（TR-XRD）等温还原一系列大小分散的Cu2O纳米晶体（+/- 7％）的系统分析提供了Cu2O的时间分辨相分数和还原时的时间Cu（fcc）首先出现。纳米Cu 2 O的初始相分数小于1，其余部分归因于非晶CuO壳。由于未观察到结晶CuO（单斜晶）的峰，因此提出了具有非晶CuO壳的核壳结构。根据分析，当Cu2O从主体中减少到8 nm时，对应于外壳的Cu2 +含量将从0％增加到33％。基于还原曲线，为还原过程中观察到的Cu2O相行为构建了时间尺寸缩减（TSR）图。掺入纳米CeO2载体（7 nm）可以在还原性气氛中显着稳定我们的纳米Cu2O。当使用较大的微晶尺寸的CeO2（20 nm）载体时，CeO2-y的氧非化学计量方面的供氧倾向显示较低。通过Madelung模型分析并解释了纳米CeO2载体中较大的氧气容量，该模型具有纳米铈土的尺寸依赖性体积模量。

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