CO氧化催化在碳的同素異形體－Penta-graphene基底材料之理論計算研究

Computational study of catalytic CO oxidation on new carbon allotropes of penta-graphene based materials

任剛(Ranganathan Krishnan)

指導教授 ： 陳欣聰博士

中原大學/理學院/化學研究所/博士(2020年)

https://doi.org/10.6840/cycu202000866

摘要

第一部分：Penta-graphene表面之CO氧化催化反應理論計算研究。
我們利用第一原理計算一氧化碳在碳的同素異形體－penta-graphene (PG)上之CO氧化催化能力。CO氧化反應牽涉 CO + O2 → CO2 + O 及 CO + O → CO2 兩反應和Eley–Rideal (ER) 及 Langmuir–Hinshelwood (LH) 兩種反應機制。ER反應機制為以PG材料上預吸附之O2進行CO氧化，能障為約0.65 eV；LH反應機制將共吸附之CO和O2進行反應，能障為約0.31 eV。計算數值近似於以貴重金屬進行催化實驗之結果。我們進一步分析各ER和LH機制之LDOS，以深討PG材料之催化性質。計算結果顯示PG為無金屬、有潛力且低價格之低溫CO氧化催化劑。本研究致力於設計及改進碳同素異形體之催化和應用。
第二部分：N摻雜penta-graphene表面之CO氧化催化理論計算研究。
在一氧化碳氧化催化N-doped penta-graphene (NPG)之spin-polarized density functional theory (DFT)計算中。考慮兩種可能反應路徑Eley–Rideal (ER) 及Langmuir–Hinshelwood (LH) 機制。結果顯示，NPG具有很強的催化活性及其在低溫CO氧化催化之速率決定步驟僅有非常微小的反應能障，優於許多金屬基或碳基催化劑（ER反應路徑沒有活化能，且LH路徑能障僅0.33 eV）。本研究提出了新的二維碳基材料設計，提供設計低成本而高催化活性CO氧化催化劑之思路。

第三部分：B摻雜及BN共摻雜penta-graphene表面之CO氧化催化理論計算研究。
我們使用spin-polarized density functional theory (DFT)探討硼摻雜和硼氮共摻雜PG材料之CO氧化催化能力。找出了Eley–Rideal (ER)、Langmuir–Hinshelwood (LH)和Tri-molecular Eley-Rideal (TER)機制，其中TER為新提出的CO氧化機制。計算結果指出ER、LH和TER機制皆可以以相對小的總體能障進行（ER機制為約0.11～0.35 eV、LH機制為約0.16～0.17 eV而TER機制沒有活化能）。本研究能幫助理解CO氧化過程中不同的反應路徑及B摻雜和BN共摻雜之PG材料為無金屬且潛力無窮的低溫CO氧化催化劑。
第四部分：Single-Pt atom supported penta-graphene表面之CO氧化催化理論計算研究。
運用spin-polarized density functional theory (DFT)計算Single-Pt atom supported penta-graphene (Pt/PG)。Single-atom catalysts (SACs) 因為其獨特的CO氧化行為而獲得不小的討論度。Pt/PG氧化CO可能的機制牽涉兩種傳統機制，Eley–Rideal (ER)、Langmuir–Hinshelwood (LH)和Tri-molecular Eley-Rideal (TER)機制。計算結果顯示，ER路徑(O2+ CO → O + CO2)和TER路徑(2CO + O2 → OCO–OCO → 2CO2)之活化能各別為0.11~0.20 eV和其速率決定步驟0.35 eV，易於LH路徑（0.45 eV）。TER路徑因其CO吸附較O2強而為最佳路徑，ER路徑可以被限制。這個發現顯示單原子催化劑Pt/PG具有絕佳的CO氧化催化活性，開創了設計penta graphene單原子催化劑新策略。

關鍵字

CO氧化催 ； Penta-graphene

並列摘要

1st part: The catalytic oxidation of CO on pristine penta-graphene (PG) surfaces investigated with theoretical calculations
To study the catalytic CO oxidation on a new carbon allotrope called penta-graphene (PG) performed by first-principles calculations The CO oxidation involves CO + O2 → CO2 + O and CO + O → CO2 reactions considering through Eley–Rideal (ER) and Langmuir–Hinshelwood (LH) mechanisms. The ER mechanism proceeds the oxidization of CO to CO2 by the pre-adsorbed O2 on the PG sheet. The energy barrier is predicted to be 0.65 eV. The LH mechanism takes place by co-adsorbed CO and O2 on PG sheet with an energy barrier as low as 0.31 eV. These predicted values are quite close to those processes catalyzed by noble metals. In addition, we analyzed the LDOS at each step of ER and LH mechanisms to deeply understand the catalytic properties of PG. Our calculation results illustrate that PG is a potential, metal-free, and low-cost catalyst for low-temperature CO oxidation. This study contributes to designing more effective carbon allotrope catalysts and widening the applications of carbon allotrope.
2nd part: The catalytic oxidation of CO on N-doped penta-graphene surfaces investigated with theoretical calculations
A systematic study of catalytic carbon monoxide oxidation on the nitrogen-doped penta-graphene (NPG) by utilizing spin-polarized density functional theory calculations. The possible reaction pathways via both Eley–Rideal (ER) and Langmuir–Hinshelwood (LH) mechanisms were illustrated. The results manifest that the nitrogen-doped penta-graphene displays very high catalytic activity and is more competitive with many metal-based and carbon-base catalysts for low-temperature CO oxidation by reason of the very small energy barrier of the rate-limiting step (there is no activation energy for the ER mechanism and only 0.33 eV for the LH mechanism). This study opens a new avenue for the design of 2-D graphene-based materials and provides valuable clues for developing low-cost and highly catalytic activity for low-temperature CO oxidations.
3rd part: The catalytic oxidation of CO on B-doped and BN co-doped penta-graphene surfaces investigated with theoretical calculations
We performed a spin-polarized density functional theory (DFT) calculations to investigate the catalytic reaction of carbon monoxide oxidation on boron-doped and boron-nitrogen co-doped penta-graphene materials have been systematically studied. Various pathways including Eley–Rideal (ER), Langmuir–Hinshelwood (LH), and Tri-molecular Eley–Rideal (TER) mechanisms were considered in which the TER mechanism is newly proposed reaction mechanism for CO oxidation. According to the calculation results, the ER, LH and TER mechanisms of CO oxidation process are possible to occur and compete each other with the related small overall reaction energy barriers (0.11 ~ 0.35 eV for the ER mechanism, 0.16 ~ 0.17 eV for the LH mechanism, and no activation energy for the TER mechanism). Our study helps to understand the various pathways for the CO oxidation process and suggests that both B-doped and BN co-doped penta-graphene sheets may serve as metal-free and potential catalysts for low-temperature CO oxidation.
4th part: The catalytic oxidation of CO on a single Pt atom supported by penta-graphene surfaces investigated with theoretical calculations
We applied a spin-polarized first-principles calculation to investigate the catalytic reaction of CO oxidation on single Pt atom supported on penta-graphene (Pt/PG) has been computation explored. Single-atom catalysts (SACs) have been gained special attractions due to their distinguishing performances for CO oxidation. The possible mechanisms of CO oxidation by O2 on the Pt/PG involving two traditional Eley–Rideal (ER) and Langmuir–Hinshelwood (LH) mechanisms and a new tri-molecular Eley-Rideal (TER) mechanism are illustrated. Our computations reveal that direct ER pathway (O2+ CO → O + CO2) and TER pathway (2CO + O2 → OCO–OCO → 2CO2) with activation energies of 0.11 ~ 0.20 eV and 0.35 eV for the rate-limiting step, respectively, are more preferable than that (0.45 eV) of LH pathway. The TER pathway is proposed to be the most favored one since the adsorption of CO is much stronger than the adsorption of O2, the ER pathway can be restrained. This finding demonstrates that the Pt/PG as a single-atom catalyst exhibits excellent catalytic activity toward CO oxidation and opens a new strategy to design single-atom catalysts based on penta-graphene.

並列關鍵字

CO oxidation ； Penta-graphene based materials

參考文獻

REFERENCES

1. Shen, Y.; Guo, Y.; Wang, L.; Wang, Y.; Guo, Y.; Gong, X.; Lu, G., The stability and deactivation of Pd–Cu–Clx/Al2O3 catalyst for low temperature CO oxidation: an effect of moisture. Catal. Sci. Technol, 2011, 1 (7), 1202-1207.

2. Liu, L.; Zhou, F.; Wang, L.; Qi, X.; Shi, F.; Deng, Y., Low-temperature CO oxidation over supported Pt, Pd catalysts: Particular role of FeOx support for oxygen supply during reactions. J. Catal, 2010, 274 (1), 1-10.

3. Wang, J.; Wang, Z.; Liu, C.-J., Enhanced activity for CO oxidation over WO3 nanolamella supported Pt catalyst. ACS Appl. Mater. Interfaces, 2014, 6 (15), 12860-12867.

4. Qiao, B.; Wang, A.; Yang, X.; Allard, L. F.; Jiang, Z.; Cui, Y.; Liu, J.; Li, J.; Zhang, T., Single-atom catalysis of CO oxidation using Pt 1/FeOx. Nat. Chem, 2011, 3 (8), 634.