Regulating photocatalysis by the oxidation state of titanium in TiO₂/TiO

The current research on the CO₂RR process mainly focuses on the high selectivity of a single product and the material selectivity in the path process [1],[2] Guo et al ., 2019. There are relatively few studies on changes and causes. In this work, TiO₂/TiO formed by in-situ oxidation was used as a photocatalyst for CO₂ reduction. The structure of this semiconductor/metal-like heterojunction makes the internal electric field appear in the catalyst, which greatly improves the activity of the photocatalytic reaction. During the test, it was found that the hydrogenation product gradually appeared in the reaction product due to the appearance of TiO₂. In the absence of a sacrificial agent, the catalyst exhibited a high HCOOH selectivity and obtained a considerable yield of 46.37 μmol g^-1h^-1. After adding the sacrificial agent triethanolamine (TEOA), TiO₂/TiO showed good CO production ability. As the reaction progressed, CH₄ was gradually produced. DFT calculations confirmed that the structure of the heterojunction has lower workfunction for the CO₂ hydrogenation option, and the energy band at the contact position is curved. The construction of this system has guiding significance for the construction of light-driven CO₂ hydrogenation products in the future.