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The inhibition effect of Sn2+ on the anodic dissolution of Fe-0.05C steel was investigated electrochemically in a solution of 0.2 M HClO4. Anodic currents were suppressed in the presence of Sn2+, and the suppression behavior depended on the concentration of Sn2+ and the electrode potentials. The experimental condition for the current suppression is explained by the theory of underpotential deposition (UPD). X-ray photoelectron spectroscopy (XPS) depth analysis revealed the deposition of metallic Sn on the steel, while inductively coupled plasma-mass spectrometry (ICP-MS) analysis demonstrated that the Sn layer thickness was monolayer-level. This strongly suggests that the anodic dissolution of iron was suppressed by the UPD of Sn. The proposed mechanism for corrosion inhibition by Sn-UPD also explains the superior corrosion resistance of Sn-bearing steel under atmospheric environments. [ABSTRACT FROM AUTHOR]

The use of SnO2 as an alternative electrocatalyst support improves durability against voltage cycling up to a high potential, conesponding to the start-up and shut-down situation of polymer electrolyte fuel cell (PEFC) systems. Electrochemical surface area (ECSA) and oxygen reduction reaction (ORR) activity of Pt electrocatalysts as well as electrical conductivity of the electrocatalyst layers increase by doping of SnO2 with Nb or Sb. The durability tests with voltage cycles between 0.9 and 1.3 V versus reversible hydrogen electrode (RHE) potential have revealed that the Pt electrocatalyst supported on SnO2 (Pt/SnO2) withstands 60,000 voltage cycles while maintaining its ECSA, which corresponds to a lifetime of more than 20 years with respect to the durability against voltage cycling. These results indicate that SnO2-supported carbon-free electrocatalysts can be alternatives to the conventional Pt/C electrocatalyst, as a fundamental solution against carbon support corrosion, to improve PEFC durability. [ABSTRACT FROM AUTHOR]