Photothermal Catalysis over Nonplasmonic Pt/TiO2 Studied by Operando HERFD-XANES, Resonant XES, and DRIFTS

There is strong interest in developing photothermal catalysts that can utilize both thermal energy and low-intensity photon flux. The complementary use of operando diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), high-energy-resolution fluorescence detected X-ray absorption near-edge structure (HERFD-XANES), and X-ray emission spectroscopy (XES) provided mechanistic insight into the photothermal catalytic oxidation of CO over Pt/TiO2. The methods turned out to be sensitive enough to uncover a change in the electronic structure of the Pt sites upon light illumination. The Pt sites on TiO2 were found to be more oxidized upon light illumination. The CO coverage is reduced, which results in a ∼20-fold rate enhancement of CO oxidation at 45 °C. Finally, a promising operando spectroscopic route to understand photothermal catalytic reactions is proposed.