利用密度泛函理論探討一氧化碳在無金屬催化劑-硼摻雜奈米碳管的氧化反應

Density functional theory calculations on boron-doped carbon nanotubes as a potential metal-free catalyst for CO oxidation

高偉桓(Wei-Huan Kao)

指導教授 ： 陳欣聰

中原大學/理學院/化學研究所/碩士(2018年)

https://doi.org/10.6840/cycu201800450

摘要

本篇研究是利用密度泛函理論計算去探討利用不同含量之硼摻雜的奈米碳管當作無金屬催化劑，用來催化一氧化碳來做比較，並再進一步的對比氧化反應的催化活性，最後推斷出最佳的比例。
首先探討O2的吸附，同時運用Bader charge進行電荷分析，其最佳的吸附位置是C-B site，在B-doped carbon nanotubes中，O2最穩定的吸附能為 -0.85 eV；在BB-doped carbon nanotubes中為 -1.29 eV。
接著我們再對CO進行催化作用形成氧化反應，分為兩部分: (1) CO + O2 → CO2 + O (remaining)，其中在 B-doped 催化所需的活化能為 0.34 eV、而在BB-doped 的活化能為0.42 eV; (2) O (remaining) + CO → CO2，而此步驟在B-doped 和 BB-doped 的活化能分別為0.12 eV和0.14 eV。經過的反應是藉由 Eley-Rideal mechanism (ER) 來產生二氧化碳，而此材料表面經過兩次反應可以回到初始狀態，並可重複循環利用。經由計算後發現，摻雜硼原子在碳米碳管上不僅改善了對於氧氣的吸附能力，也有效地降低了CO氧化反應的活化能，研究結果亦顯示增加硼原子的含量對於氧氣的穩定度確實得到提升。

關鍵字

DFT計算 ； 奈米碳管 ； Eley-Rideal反應機制 ； 一氧化碳氧化反應

並列摘要

By means of density functional theory (DFT) calculation, we used the carbon nanotubes with different content of doped boron as potential metal-free catalysts for the CO oxidation. In order to find the possible active sites for CO oxidation, we investigated the O2 -adsorption behavior on different position of 1 and 2 B-doped carbon nanotubes and find the most stable structures of adsorbed O2 are flat on C-B site of both nanotubes with the adsorption energies of -0.85 and -1.29 eV, respectively.
Then we investigated the catalytic reaction paths of CO oxidation, divided into two parts: (1) CO + O2* → CO2 + O*, where the activation energy required for B-doped and BB-doped catalysts are 0.34 eV and 0.42 eV, respectively; (2) O* + CO → CO2: the activation energy required for BB-doped is 0.14 eV. The reaction is through the Eley-Rideal mechanism (ER) to produce carbon dioxide. After two CO oxidation processes, the carbon nanotubes can be recovered to their original structures and recycled.
After calculation, we found that B-doped carbon nanotubes not only improved adsorption capacity of O2, but also reduced the activation energy of CO oxidation. According to our research, the higher stability of O2 , the more boron-doped content.

並列關鍵字

DFT calculation ； carbon nanotube ； Eley-Rideal mechanism ； CO oxidation

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