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首页> 外文期刊>Crystal growth & design >Morphology Controlled Solution-Based Synthesis of Cu2O Crystals for the Facets-Dependent Catalytic Reduction of Highly Toxic Aqueous Cr(VI)
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Morphology Controlled Solution-Based Synthesis of Cu2O Crystals for the Facets-Dependent Catalytic Reduction of Highly Toxic Aqueous Cr(VI)

机译：形态控制的基于溶液的Cu2O晶体合成，用于高毒性Cr（VI）的晶面催化还原

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摘要

In this study, we demonstrate the systematic shape evolution of Cu2O crystals from the octahedron, through truncated octahedron, cube, and finally to truncated cube by varying the reaction temperature with an optimum precursor concentration of 25 mM Cu(NO3)(2)center dot 3H(2)O and 1 g of polyvinylpyrrolidone (PVP) as the shape controlling reagent. The average size of these crystals increased with temperature from similar to 70 nm (at 40 degrees C) to (at 100 degrees C). With a much lower (6 mM) and higher (250 mM) precursor concentration, nanoparticles and polyhedron-shaped crystals are respectively formed in the studied temperature region (40-120 degrees C). The role of precursor concentration, PVP quantity, reaction medium, and reaction temperature in the formation of diverse Cu2O crystals morphologies are demonstrated and discussed. Furthermore, the catalytic activity of the as-synthesized Cu2O crystals is tested for the reduction of Cr(VI) at room temperature. The toxic Cr(VI) is found to be rapidly reduced to nontoxic Cr(III) in a short span of 4 min in the presence of Cu2O cubes in the acidic medium. The repeat catalytic measurements of Cr(VI) reduction for 20 cycles confirm higher stability of cube-shaped Cu2O crystals with {100} exposed facets as compared to octahedrons with {111} exposed facets, a classic example of facets-dependent catalytic properties of crystals.
机译：在这项研究中，我们通过改变最佳前驱体浓度为25 mM Cu（NO3）（2）中心点的反应温度，证明了Cu2O晶体从八面体到截顶八面体，立方，最后到截顶立方的系统形状演变。 3H（2）O和1 g聚乙烯吡咯烷酮（PVP）作为形状控制试剂。这些晶体的平均尺寸随温度从大约70 nm（在40摄氏度）增加到（在100摄氏度）而增加。在较低的（6 mM）和较高的（250 mM）前驱体浓度下，在研究的温度区域（40-120摄氏度）分别形成了纳米颗粒和多面体形晶体。并讨论了前驱体浓度，PVP量，反应介质和反应温度在形成各种Cu2O晶体形态中的作用。此外，在室温下测试了合成后的Cu2O晶体的催化活性以减少Cr（VI）。发现在酸性介质中存在Cu2O立方体的情况下，在短短4分钟内，有毒的Cr（VI）会迅速还原为无毒的Cr（III）。重复进行20次循环的Cr（VI）还原催化测量，证实具有{100}暴露面的立方体形Cu2O晶体比具有{111}暴露面的八面体具有更高的稳定性，这是晶体依赖于面的催化性质的经典示例。

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