Effect of O<inf>2</inf> on the adsorption of SO<inf>2</inf> on carbon-supported pt electrocatalysts

• Main Authors: K. Punyawudho, S. Ma, J. W. Van Zee, J. R. Monnier
• Format: Journal
• Published: 2018
• Subjects: Chemistry; Materials Science; Physics and Astronomy
• Online Access: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=79959194285&origin=inward; http://cmuir.cmu.ac.th/jspui/handle/6653943832/49820
• Institution: Chiang Mai University

Adsorption of SO2 in the presence of O2 on Pt/C catalysts often used as electrocatalysts has been investigated by temperature programmed desorption (TPD) and X-ray photoelectron spectroscopy (XPS). The amounts of SO2 adsorption on Pt/C in the presence of O2 were much higher than those in the absence of O2 (SO 2-N2) and from the carbon support (Vulcan XC-72) alone. Adsorption is dependent on oxygen concentration over the range 0-20% but reaches saturation at 20% O2. The spillover of SO2 from Pt to the carbon support has been proposed for 10, 20, and 40% Pt loadings, characterized by desorption temperatures of approximately 150 and 260 °C for SO 2 adsorbed on Pt and carbon, respectively. Adsorbed Pt-S, C-S, C-SOx, and Pt-SO4 species were identified by XPS as S-containing species on both Pt and carbon. Both TPD and XPS indicate that the carbon support plays a major role in SO2 adsorption, primarily as SOx (x = 3, 4). The bonding of S and SOx on the carbon support was strong enough that back diffusion to the Pt surface did not occur. © 2011 American Chemical Society.