Photocatalytic Deacon Reaction over SrTiO 3

SrTiO 3 was prepared by a polymeric precursor method and applied in the photocatalytic aerobic oxidation of HCl in a flat‐plate reactor equipped with a UV LED array (368 nm). Reaction rates up to 240 mmol h −1  m −2 and apparent quantum yields up to 33 % using an illuminated area of 60 cm −2 were achieved with highly crystalline SrTiO 3 calcined at 750 °C, outperforming commercially available SrTiO 3 by a factor of almost 2. A gradual catalyst deactivation was observed, which was due to the formation of crystalline SrCl 2 ×2 H 2 O on the surface confirmed by X‐ray diffraction, electron microscopy and X‐ray photoelectron spectroscopy (XPS). Increasing the HCl partial pressure accelerated both Cl 2 formation and catalyst deactivation. XP spectra revealed an intrinsic surface segregation of Sr and the presence of several Sr‐ or O‐containing surface species. High Cl 2 yields up to 42 % obtained with an illuminated area of 120 cm −2 encourage further research on a photocatalytic Deacon process for improved HCl recycling.