Photo–thermo Catalytic Oxidation over a TiO₂‐WO₃‐Supported Platinum Catalyst

Abstract

Photo-thermo catalysis, which integrates photocatalysis on semiconductors with thermocatalysis on supported nonplasmonic metals, has emerged as an attractive approach to improve catalytic performance. However, an understanding of the mechanisms in operation is missing from both the thermo- and photocatalytic perspectives. Deep insights into photo-thermo catalysis are achieved via the catalytic oxidation of propane (C₃ H₈ ) over a Pt/TiO₂ -WO₃ catalyst that severely suffers from oxygen poisoning at high O₂ /C₃ H₈ ratios. After introducing UV/Vis light, the reaction temperature required to achieve 70 % conversion of C₃ H₈ lowers to a record-breaking 90 °C from 324 °C and the apparent activation energy drops from 130 kJ mol^-1 to 11 kJ mol^-1 . Furthermore, the reaction order of O₂ is -1.4 in dark but reverses to 0.1 under light, thereby suppressing oxygen poisoning of the Pt catalyst. An underlying mechanism is proposed based on direct evidence of the in-situ-captured reaction intermediates.