Identification of the active site is important in developing rational design strategies for solid catalysts but is seriously blocked by their structural complexity. Here, we use uniform Cu nanocrystals synthesized by a morphology-preserved reduction of corresponding uniform Cu₂O nanocrystals in order to identify the most active Cu facet for low-temperature water gas shift (WGS) reaction. Cu cubes enclosed with {100} facets are very active in catalyzing the WGS reaction up to 548 K while Cu octahedra enclosed with {111} facets are inactive. The Cu-Cu suboxide (Cu_xO, x ≥ 10) interface of Cu(100) surface is the active site on which all elementary surface reactions within the catalytic cycle proceed smoothly. However, the formate intermediate was found stable at the Cu-Cu_xO interface of Cu(111) surface with consequent accumulation and poisoning of the surface at low temperatures. Thereafter, Cu cubes-supported ZnO catalysts are successfully developed with extremely high activity in low-temperature WGS reaction.Nanocrystals display a variety of facets with different catalytic activity. Here the authors identify the most active facet of copper nanocrystals relevant to the low-temperature water gas shift reaction and further design zinc oxide-copper nanocubes with exceptionally high catalytic activity.

中文翻译：

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最活跃的Cu晶面，适用于低温水煤气变换反应。

活性位点的识别对于制定合理的固体催化剂设计策略很重要，但由于其结构复杂性而受到严重阻碍。在这里，我们使用通过形态保持相应的均匀Cu ₂ O纳米晶还原而合成的均匀Cu纳米晶，以识别用于低温水煤气变换（WGS）反应的最活跃的Cu晶面。封闭在{100}刻面中的Cu立方在催化WGS反应直至548 K时非常活跃，而封闭在{111}刻面中的Cu八面体则没有活性。Cu（100）表面的Cu-Cu低氧化物（Cu _x O，x≥10）界面是在催化循环内所有基本表面反应都能顺利进行的活性位点。但是，发现甲酸中间体在Cu-Cu _x处稳定Cu（111）表面的O界面在低温下随之积累和中毒。此后，成功地开发了在高温WGS反应中具有极高活性的Cu负载型ZnO催化剂。纳米晶体具有多种具有不同催化活性的晶面。在这里，作者确定了与低温水煤气变换反应有关的铜纳米晶体的最活泼的一面，并进一步设计了具有极高催化活性的氧化锌-铜纳米立方体。