Computational Investigation of Water-Gas-Shift Reaction (WGSR) on (100) (110) (111) and (211) Facets of Au and Pt

• Main Authors: Zeng, Shu-Huang, 曾書皇
• Other Authors: Wang, Jeng-Han
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/77435019079725373245

碩士 === 國立臺灣師範大學 === 化學系 === 104 === Water gas shift reactions (WGSR) has been systematically examined on different facets of (111), (100), (110) and (211) of the most active catalysts of Pt and Au to optimize the structure effect of the catalytic reaction. Initially, the adsorption energy of key intermediates (CHO, CO, CO2, COOH, H, H2O, HCOO, O, OH) in WGSR on those facets has been computed. The energetic result finds that the opened (100) and (110) and stepped (211) facts have slightly stronger adsorption energies than (111) facet in most case and all the adspecies adsorbed stronger on Pt than Au surfaces. Furthermore, we examined the reaction energies and activation barriers for the three major pathways of WGSR, carboxyl, redox and formate, on those facets. The energetic results show that the Pt(111) prefer carboxyl pathway while the Pt(211)、Pt(100), Au(100), Au(110), Au(211) , Au(111)favor redox pathway. Formate pathway has relatively higher energetics and is less likely to occur on any surfaces. All the Au facets have lower energetics than the Pt ones, implying Au is a better catalyst for WGSR. Also, the rate determining steps of favored pathways on those surface show limited differences, indicating that the modification of facets could change the reaction pathways, but not likely alter the catalytic activity for WGSR. Appendix Ethanol oxidation reaction contains two major pathways (1)C-C cleavage involve 12 electrons transform ,called C1 pathway (2)ethanol oxidative to aldehyde including 2 electrons transform, continue to oxidative aldehyde to acetic acid including 2 electrons transform. To identify mechanism, we test activity of catalysts by CV, stability by CA, products by in situ IR. We change concentration of electrolyte and solution volume to observe mechanism .Scam range from -0.9 to 0.6 V. When electrolyte is 2 M, the catalyst had the best activity and stability and solution volume don’t had no trend to catalyst.