在理想情況下，催化劑除了化學和結構穩定性外，還應具有高活性及選擇性且價格低廉，但單一金屬奈米晶體無法滿足，而這些可以透過添加第二種金屬形成雙金屬奈米晶體時產生的協同作用來滿足。多種金屬可以分成無序及有序晶體結構，分別稱為合金及金屬間奈米晶體。合金為多種金屬簡單混合及隨機分佈的化合物；金屬間奈米晶體為具有明確的化學計量及良好的晶體結構，其為有序原子排列的化合物。金屬間奈米晶體有序的原子排列與合金奈米晶體相比具有更強烈的電子相互作用、均勻的催化活性位點、鍵長和電子結構顯著變化以及因為金屬間奈米晶體的生成熱低於合金，所以它的催化活性及耐腐蝕性皆比合金好。由於不同形狀露出的晶面不同，導致催化反應上會有不同的催化效果，故我們希望能夠合成出不同形狀的金屬間奈米晶體。本實驗室選擇具有良好催化性能的鈀與價格較便宜的銅，透過共還原反應成功合成出金屬間截角菱形十二面體及立方體。希望未來我們可以比較不同晶面對催化效果的影響。

Ideally, a catalyst should be highly active, selective and inexpensive, as well as chemistry and structural stability. However a single metallic nanocrystals cannot meet these basic requirements, which can be met by the synergistic effect of adding a second metal to form a bimetallic nanocrystals. Multiple metals can be classified into two types with disordered and ordered alloys, which called alloys and intermetallics, respectively. Alloys are compounds with simple mixing and random distribution of multiple metals; intermetallics are compounds with well-defined chemical composition and crystal structure with long-range atomic arrangement. The intermetallics have stronger electronic interactions, homogeneous catalytic active sites, significant changes in bond lengths and electronic structure than alloys. The catalytic activity and corrosion resistance of intermetallics are better than those of alloys because the heat of generation of intermetallic nanocrystal is lower than that of alloys. Since the different shapes of the exposed surfaces lead to different catalytic activity in catalytic reactions, we hope to synthesise intermetallic nanocrystals with different morphologies. In this work, Pd and Cu have been chosen, which have good catalytic properties. Intermetallic PdCu nanocrystals with the shapes of truncated rhombic dodecahedron and cube were successfully synthesized by coreduction reaction. In the future, the activity of different crystalline surfaces will be compared.

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