Methanol oxidation on Ru(0001) for direct methanol fuel cells: analysis of the competitive reaction mechanism. Issue 3 (24th December 2015)

• Record Type: Journal Article
• Authors: Lu, Xiaoqing; Wang, Weili; Deng, Zhigang; Zhu, Houyu; Wei, Shuxian; Ng, Siu-Pang; Guo, Wenyue; Wu, Chi-Man Lawrence
• Is Part Of: RSC advances. Volume 6:Issue 3(2016)
• Page Start: 1729
• Page End: 1737
• Publication Date: 2015-12-24
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c5ra21793h
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : Competitive oxidation of CH3 OH to CH2 O occur via CH3 OH → CH3 O → CH2 O vs. CH3 OH → CH2 OH → CH2 O, further to COOH by the OH group via CH2 O → CHO → CO + OH → COOH vs. CH2 O + OH → CH2 OOH → CHOOH → COOH, and finally oxidation to CO2 on Ru(0001). Abstract : The competitive oxidation reaction mechanism of methanol on the Ru(0001) surface has been investigated by periodic density functional theory (DFT). Stable adsorption configurations, elementary reaction energies and barriers, the potential energy surface (PES), and the electrochemical potential analysis were elucidated. The results showed that O–H bond activation was more competitive than C–H and C–O bond activation during the initial methanol oxidation. Competitive pathways occurred for CH3 OH oxidation to CH2 O via CH3 OH → CH3 O → CH2 O versus CH3 OH → CH2 OH → CH2 O, further to COOH via the CO pathway CH2 O → CHO → CO → COOH versus the non-CO pathway CH2 O → CH2 OOH → CHOOH → COOH, and finally oxidation to CO2 . Taking PES and the electrochemical potential analysis into account, CH3 OH → CH2 OH → CH2 O → CH2 OOH → CHOOH → COOH → CO2 appeared to be the preferred oxidation pathway. The OH group could inhibit CO formation by directly reacting with CH2 O to yield CH2 OOH but could not efficiently remove the CO that had already been produced by the reactions.