本研究以第一原理計算分析無機石墨烯材料摻雜金屬鋁之觸媒將二氧化碳還原成甲醇能源之再利用，從計算量子化學(computational quantum chemistry)出發，研究二氧化碳還原途徑，採用密度泛函理論中的B3LYP，透過Gaussian軟體研究鋁摻雜石墨烯(Al-doped graphene, AlDG)基材對二氧化碳還原機制進行研究。本研究流程設計如下：模型建立(model establishment)、幾何優化(geometry optimization)、過渡狀態搜索(transition state search)和內在反應坐標(intrinsic reaction coordinate, IRC)分析，最後利用以熱力學原理及過渡態理論為基礎所建立之動力學及統計熱力學模組(Kinetic and Statistical Thermodynamical Package, KiSThelP)將Gaussian 09所計算之能量結果經由KiSThelP圖形化介面求得材料之各項熱力學性質、反應速率常數k以及反應平衡常數K等。
研究中發現小片AlDG為一凸面型結構，此結果與文獻相符。首先進行反應物及產物結構優化求得最穩定能量，CO2和AlDG之間的相互作用顯示，CO2的O末端將朝向Al原子而不是C原子，此結果也與文獻相同。而還原過程中，O原子從CO2中分解出並鑲嵌至AlDG的Al和C原子之間，之後加入H+及e-逐步進行還原反應，反應後回到原本的AlDG結構，而形成Al原子鍵結HO*分子，再次還原後形成HO*及CHO*接在AlDG結構上，接著CHO*依序被還原成CHOH*而後為CH2OH*，最後形成CH3OH。最後提供的H+及e-會將HO*還原成水，提供的兩個電子會使產物CH3OH及H2O從AlDG結構中釋出。
過程中出現許多能量相近的結構，經Gaussian 09的過渡態搜尋，找尋各步驟反應之過渡態能量屏障，扣除反應物能量後可以得到反應活化能，再經由IRC驗證反應過渡態結構。最後由KiSThelP的過渡態理論所得到之反應速率常數k把Gaussian 09搜尋得到之過渡態反應活化能轉換求得反應速率常數k、反應平衡常數K。

In this study, first-principles calculations were carried out to analyze the catalysis process of CO2 reduction into methanol at the aluminum doped graphene framework. Using the computational quantum mechanics technique, the carbon dioxide reduction pathway was studied through the density functional theory (DFT) with the Gaussian software. The main focus of this study is on the investigation of reduction mechanism of carbon dioxide at the surface of the Al-doped graphene (AlDG) substrates. Research methodologies follow the steps as follows: molecular model establishment, geometry optimization, transition state search and intrinsic reaction coordinate (IRC) analysis. Finally, we used the KisThelp (Kinetic and Statistical Thermodynamical Package), which is a cross-platform free open-source program developed to estimate molecular and reaction properties from electronic structure data, to determine the reaction rate constant.
The molecular structure of a small piece of the AlDG is in a bending form after minimum energy geometry optimization and the adsorption energy of CO2 absorbed by the AlDG is about -0.328 eV. The interaction between CO2 and AlDG shows that the O-terminal of the CO2 is towards to the catalyst Al atom, not the C atom of the grapheme.This is due to the electronic negativity of the O atom. During the reduction process, CO2 decomposes into two parts, CO and O atom, and the later is attached between the Al and the C of the AlDG. Via the addition of electrons, the CO2 is potentially to be successfully reduced to methanol and water.
Through the transition state search in the Gaussian 09, the transition state energy barrier for each step reaction can be found and hence the activation energy of the reaction can be obtained. The transition state electronic structure data can be confirmed through the IRC analysis and input to the KiSThelP is to calculate the reaction rate constants.

1. Le Quéré C., Andres R. J., Boden T., et al.,The global carbon budget 1959–2011,Earth Syst. Sci. Data 2013, 5, 165-185.
2. Maginn E. J.,What to Do with CO2,The Journal of Physical Chemistry Letters 2010, 1, 3478-3479.
3. Metz B., Davidson O., Coninck H. d., et al., IPCC Special Report on Carbon Dioxide Capture and Storage, Cambridge, 2005.
4. in Small Medium Large Calcium-Looping CO2 Capture Technology, Industrial Technology Research Institute.
5. Sutter P.,Epitaxial graphene: How silicon leaves the scene,Nat Mater 2009, 8, 171-172.
6. Leenaerts O., Partoens B., Peeters F. M.,Water on graphene: Hydrophobicity and dipole moment using density functional theory,Physical Review B 2009, 79, 235440.
7. Cioslowski J., Liu G., Martinov M., et al.,Energetics and Site Specificity of the Homolytic C−H Bond Cleavage in Benzenoid Hydrocarbons:  An ab Initio Electronic Structure Study,Journal of the American Chemical Society 1996, 118, 5261-5264.
8. Montoya A., Truong T. N., Sarofim A. F.,Spin Contamination in Hartree−Fock and Density Functional Theory Wavefunctions in Modeling of Adsorption on Graphite,The Journal of Physical Chemistry A 2000, 104, 6108-6110.
9. Mishra A. K., Ramaprabhu S.,Carbon dioxide adsorption in graphene sheets,AIP Advances 2011, 1, 032152.
10. Gensterblum Y., van Hemert P., Billemont P., et al.,European inter-laboratory comparison of high pressure CO2 sorption isotherms. I: Activated carbon,Carbon 2009, 47, 2958-2969.
11. Zhang Z., Xu M., Wang H., Li Z.,Enhancement of CO2 adsorption on high surface area activated carbon modified by N2, H2 and ammonia,Chemical Engineering Journal 2010, 160, 571-577.
12. Cavenati S., Grande C. A., Rodrigues A. E.,Adsorption Equilibrium of Methane, Carbon Dioxide, and Nitrogen on Zeolite 13X at High Pressures,Journal of Chemical & Engineering Data 2004, 49, 1095-1101.
13. Millward A. R., Yaghi O. M.,Metal−Organic Frameworks with Exceptionally High Capacity for Storage of Carbon Dioxide at Room Temperature,Journal of the American Chemical Society 2005, 127, 17998-17999.
14. Shokuhi Rad A., Pouralijan Foukolaei V.,Density functional study of Al-doped graphene nanostructure towards adsorption of CO, CO2 and H2O,Synthetic Metals 2015, 210, 171-178.
15. Wu J., Ma S., Sun J., et al.,A metal-free electrocatalyst for carbon dioxide reduction to multi-carbon hydrocarbons and oxygenates,Nature Communications 2016, 7, 13869.
16. Manna A. K., Pati S. K.,Tuning the Electronic Structure of Graphene by Molecular Charge Transfer: A Computational Study,Chemistry – An Asian Journal 2009, 4, 855-860.
17. Chi M., Zhao Y.-P.,Adsorption of formaldehyde molecule on the intrinsic and Al-doped graphene: A first principle study,Computational Materials Science 2009, 46, 1085-1090.
18. Zhou Z., Gao X., Yan J., Song D.,Doping effects of B and N on hydrogen adsorption in single-walled carbon nanotubes through density functional calculations,Carbon 2006, 44, 939-947.
19. Sun Y., Chen L., Zhang F., et al.,First-principles studies of HF molecule adsorption on intrinsic graphene and Al-doped graphene,Solid State Communications 2010, 150, 1906-1910.
20. Wang W., Zhang Y., Shen C., Chai Y.,Adsorption of CO molecules on doped graphene: A first-principles study,AIP Advances 2016, 6, 025317.
21. Denis P. A.,Band gap opening of monolayer and bilayer graphene doped with aluminium, silicon, phosphorus, and sulfur,Chemical Physics Letters 2010, 492, 251-257.
22. Fukui M., Norimatsu W., Kusunoki M.,Synthesis of aluminum-doped graphene by thermal decomposition of aluminum carbide,Abstract of annual meeting of the Surface Science of Japan 2016, 36, 169.
23. Shahabi D., Tavakol H.,A DFT study on the catalytic ability of aluminum doped graphene for the initial steps of the conversion of methanol to gasoline,Computational and Theoretical Chemistry 2018, 1127, 8-15.
24. Tajima N., Tsuneda T., Toyama F., Hirao K.,A New Mechanism for the First Carbon−Carbon Bond Formation in the MTG Process:  A Theoretical Study,Journal of the American Chemical Society 1998, 120, 8222-8229.
25. Sayed M. B.,Fourier-transform infrared study of the role of zeolite Lewis sites in methanol reactions over HZSM-5 surfaces,Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases 1987, 83, 1149-1157.
26. Harvey O. R., Qafoku N. P., Cantrell K. J., et al.,Geochemical Implications of Gas Leakage associated with Geologic CO2 Storage—A Qualitative Review,Environmental Science & Technology 2013, 47, 23-36.
27. D'Alessandro D. M., Smit B., Long J. R.,Carbon Dioxide Capture: Prospects for New Materials,Angewandte Chemie International Edition 2010, 49, 6058-6082.
28. Mino L., Spoto G., Ferrari A. M.,CO2 Capture by TiO2 Anatase Surfaces: A Combined DFT and FTIR Study,The Journal of Physical Chemistry C 2014, 118, 25016-25026.
29. Barton E. E., Rampulla D. M., Bocarsly A. B.,Selective Solar-Driven Reduction of CO2 to Methanol Using a Catalyzed p-GaP Based Photoelectrochemical Cell,Journal of the American Chemical Society 2008, 130, 6342-6344.
30. Low J., Yu J., Ho W.,Graphene-Based Photocatalysts for CO2 Reduction to Solar Fuel,The Journal of Physical Chemistry Letters 2015, 6, 4244-4251.
31. Takeda H., Cometto C., Ishitani O., Robert M.,Electrons, Photons, Protons and Earth-Abundant Metal Complexes for Molecular Catalysis of CO2 Reduction,ACS Catalysis 2017, 7, 70-88.
32. Bhatt M. D., Lee G., Lee J. S.,Oxygen Reduction Reaction Mechanisms on Al-Doped X-Graphene (X = N, P, and S) Catalysts in Acidic Medium: A Comparative DFT Study,The Journal of Physical Chemistry C 2016, 120, 26435-26441.
33. Joo O.-S., Jung K.-D., Moon I., et al.,Carbon Dioxide Hydrogenation To Form Methanol via a Reverse-Water-Gas-Shift Reaction (the CAMERE Process),Industrial & Engineering Chemistry Research 1999, 38, 1808-1812.
34. Lewars E. G., Computational Chemistry: Introduction to the Theory and Applications of Molecular and Quantum Mechanics, 2nd ed., Springer, Dordrecht, Trent University, Peterborough, Canada, 2011.
35. Nelsen S. F., Blomgren F.,Estimation of Electron Transfer Parameters from AM1 Calculations,The Journal of Organic Chemistry 2001, 66, 6551-6559.
36. Frisch M. J., Trucks G. W., Schlegel H. B., et al., Wallingford, CT, 2016.
37. Becke A. D.,Density‐functional thermochemistry. III. The role of exact exchange,The Journal of Chemical Physics 1993, 98, 5648-5652.
38. Lee C., Yang W., Parr R. G.,Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density,Physical Review B 1988, 37, 785-789.
39. Geim A. K.,Graphene: Status and Prospects,Science 2009, 324, 1530.
40. Berger C., Song Z., Li T., et al.,Ultrathin Epitaxial Graphite:  2D Electron Gas Properties and a Route toward Graphene-based Nanoelectronics,The Journal of Physical Chemistry B 2004, 108, 19912-19916.
41. Canepa P., Arter C. A., Conwill E. M., et al.,High-throughput screening of small-molecule adsorption in MOF,Journal of Materials Chemistry A 2013, 1, 13597-13604.
42. Esrafili M., Nematollahi P.,A Computational Investigation Of Oxygen Reduction Reaction Mechanisms On Si- And Al-doped Graphene: A Comparative Study,Advanced Materials Letters 2015, 6.