Catalytic oxidation of methanol on molybdate-modified platinum electrode in sulfuric acid solution

• Published in: Journal of power sources Vol. 104; no. 2; pp. 281 - 288
• Main Authors: Li, W.S., Tian, L.P., Huang, Q.M., Li, H., Chen, H.Y., Lian, X.P.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 15.02.2002; Elsevier Sequoia
• Subjects: Alcohols: methanol, ethanol, etc; Alternative fuels. Production and utilization; Applied sciences; Catalytic oxidation; Energy; Exact sciences and technology; Fuels; Methanol; Modification; Molybdate; Platinum; Sulfuric acid; Modification; Catalytic oxidation; Platinum; Molybdate; Methanol; Sulfuric acid; Cyclic voltammetry; Alternative fuel; Oxidation; Molybdates; Catalyst; Fuel cell
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/S0378-7753(01)00961-2

The catalysis of methanol oxidation on molybdate-modified platinum was studied by using linear sweep voltammetry (LSV), cyclic voltammetry (CV) and chronoamperometry in the solutions with H 2SO 4 concentrations from 0.5 to 4.5 M. It was found that methanol oxidation was catalyzed on the modified platinum by lowering methanol oxidation potential and promoting methanol oxidation current. There was the strongest catalysis in 3.7 M H 2SO 4 solution. In this solution, methanol oxidation took place on the modified platinum at the potential 0.2 V more negatively than on the non-modified platinum and the steady oxidation current of methanol on the modified platinum at 0.7 V versus SCE was 10 times that on the non-modified platinum. Molybdates were reduced to adsorbed hydrogen molybdenum(IV) bronzes on platinum in H 2SO 4 solution at a very negative potential. The amount of reduced molybdates decreased with decreasing H 2SO 4 concentrations. The reduced molybdates were oxidized to different forms of hydrogen molybdenum bronzes (H x MoO 3, 0< x<2) depending on the H 2SO 4 concentration. Platinum was modified by these hydrogen molybdenum bronzes, but under-modified in the solution with lower H 2SO 4 concentration and over-modified in the solution with higher H 2SO 4 concentration. The catalysis of methanol oxidation was weakened when the platinum was under- or over-modified.