一氧化碳（CO）是一種對人體有劇毒的氣體。它與人體中的血紅素有很高的親和力，經常造成疾病、窒息甚至是死亡的意外發生。因此，如何探測抑或是表面上催化CO氧化成CO2為最適當的方法。特別是在Haruta等人的突破性的發現後，使用奈米金團簇作為催化劑，將CO氧化成CO2，已然成為一個熱門的題材。
在本篇研究中，利用第一原理Vienna Ab-initio Simulation Package（VASP）將金團簇吸附在BN表面上(Au/BN)，透過電荷密度分析，瞭解表面對於金團的影響，以及於CO、O2分子吸附後的差異。除此之外，我們還藉由反應模擬探索了水對於CO氧化反應的影響。研究結果顯示，奈米金團簇不但能穩定地吸附在BN表面上，催化活性也隨著因從BN向金團的電子轉移而增強。其中，CO的伸縮振動頻率光譜會隨著含水量的增加而藍移，這現象與先前的實驗觀察結果一致。而在比較所有可能的CO氧化途徑後，我們發現在潮濕環境下，CO氧化速率決定步驟的反應障礙僅為0.28eV，亦低於先前的研究。
透過本研究，我們更加瞭解Au/BN系統如何能在低溫條件下催化CO氧化反應的原因，並且在與純金團的結果比較，瞭解表面對於金團簇的影響。期望未來能藉由表面特性分析來找出更適合之材料，提供傳統實驗以外之方法，在此提出新的觀點，以供實驗學家參考。

Carbon monoxide (CO) is a highly toxic gas for human because of its high affinity with hemoglobin, and it causes many illnesses, suffocation, and sudden death. Therefore, the elimination of CO is attracted practical importance to control the environment. In many processes, the catalytic oxidation of CO to CO2 over a heterogeneous catalyst surface is the suitable method in CO elimination. Due to the groundbreaking work of Haruta et al., (J. Catal 144, 175-192,1993) the use of gold nanoparticles as a catalyst to oxidize CO to CO2 has become an interesting topic. Previously, many theoretical and experimental studies have explored the catalytic activity of Au clusters on pure metals and metal oxide surfaces. Here we considered Au9 clusters supported on a boron-nitride sheet (BN) and investigated its catalytic activity towards CO oxidation using first-principles calculations. Furthermore, we also explored the effect of water on the CO oxidation on Au clusters supported on the boron-nitride sheet. Our results indicate that Au9 cluster is stably adsorbed on BN surface and the catalytic activity of Au9 cluster is enhanced through electron transfer from BN to Au9 cluster. We found that the stretching vibration of adsorbed CO on Au9/BN surface is blue-shifted with the increase of water content, which is in agreement with the previous experimental observation. By exploring the all possible CO oxidation pathways, we found that in presence with water on the Au9/BN surface, the reaction barrier of rate determining step of CO oxidation is only 0.28eV, which is significantly lower than the previously studies. Our calculated results suggest that Au9 clusters supported on BN surface could be a promising catalyst for CO oxidation at low-temperature conditions.

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