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/TiO 2 . 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 TiO 2 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.