Adverse effects on Pt/TiO2 lambda oxygen sensor contaminated with sulfur

Sulfur-containing additives are still widely found in fuel oil, especially in the developing countries. Sulfur is considered to have a negative impact on the electrocatalytic activity of Pt and Ni. In this work, pure TiO2 and Pt/TiO2 based lambda oxygen sensors were prepared and treated with sulfur, respectively. The gas response properties of the sensors indicated that the sulfur had adverse effects on Pt/TiO2 gas sensor, but not on the pure TiO2 sensor. The surface states of O, Pt and S present on the sensing film surface were studied by XPS in depth. The valence-state of Pt on the Pt/TiO2 sensor was proposed to be PtSO4, indicating that the catalytic activity of Pt was severely weakened by sulfur.