Methanol Oxidation on Pt3Sn(111) for Direct Methanol Fuel Cells: Methanol Decomposition.
PtSn alloy, which is a potential material for use in direct methanol fuel cells, can efficiently promote methanol oxidation and alleviate the CO poisoning problem. Herein, methanol decomposition on Pt3Sn(111) was systematically investigated using periodic density functional theory and microkinetic modeling. The geometries and energies of all of the involved species were analyzed, and the decomposition network was mapped out to elaborate the reaction mechanisms. Our results indicated that methanol and formaldehyde were weakly adsorbed, and the other derivatives (CHxOHy, x = 1-3, y = 0-1) were strongly adsorbed and preferred decomposition rather than desorption on Pt3Sn(111). The competitive methanol decomposition started with the initial O-H bond scission followed by successive C-H bond scissions, (i.e., CH3OH → CH3O → CH2O → CHO → CO). The Brønsted-Evans-Polanyi relations and energy barrier decomposition analyses identified the C-H and O-H bond scissions as being more competitive than the C-O bond scission. Microkinetic modeling confirmed that the vast majority of the intermediates and products from methanol decomposition would escape from the Pt3Sn(111) surface at a relatively low temperature, and the coverage of the CO residue decreased with an increase in the temperature and decrease in partial methanol pressure.
College of Science, China University of Petroleum , Qingdao, Shandong 266580, P. R. China.
Xiaoqing
X
Lu
Department of Physics and Materials Science, City University of Hong Kong , Hong Kong SAR, P. R. China.
Zhigang
Z
Deng
College of Science, China University of Petroleum , Qingdao, Shandong 266580, P. R. China.
Chen
C
Guo
College of Science, China University of Petroleum , Qingdao, Shandong 266580, P. R. China.
Weili
W
Wang
College of Science, China University of Petroleum , Qingdao, Shandong 266580, P. R. China.
Shuxian
S
Wei
Department of Physics and Materials Science, City University of Hong Kong , Hong Kong SAR, P. R. China.
Siu-Pang
SP
Ng
Key Laboratory for Applied Technology of Sophisticated Analytical Instruments, Shandong Academy of Sciences , Jinan, P. R. China.
Xiangfeng
X
Chen
Key Laboratory for Applied Technology of Sophisticated Analytical Instruments, Shandong Academy of Sciences , Jinan, P. R. China.
Ning
N
Ding
College of Science, China University of Petroleum , Qingdao, Shandong 266580, P. R. China.
Wenyue
W
Guo
Department of Physics and Materials Science, City University of Hong Kong , Hong Kong SAR, P. R. China.|Key Laboratory for Applied Technology of Sophisticated Analytical Instruments, Shandong Academy of Sciences , Jinan, P. R. China.
Chi-Man Lawrence
CM
Wu
Pt3Sn(111); density functional theory; direct methanol fuel cell; methanol decomposition; microkinetic modeling