Engineering oxygen vacancies in TiO2 for isotope-selective catalysis: a strategy for hydrogen isotope separation

Abstract

Deuterium and tritium are key strategic materials for the development of nuclear energy, and it is particularly important to properly treat wastewater containing deuterium (D)/tritium (T). Due to the atomic mass of deuterium and tritium being greater than that of hydrogen (H), their chemical bond vibration frequencies are lower, and their photolysis rates are usually slower. This characteristic has made the photocatalytic H₂–H₂O method a new hotspot in the field of hydrogen isotope separation. Here, we introduce a blue titanium dioxide catalyst (TiO_2−x) with an exposed highly active (001) surface. By optimizing the band structure through oxygen vacancy engineering, the separation and transfer efficiency of photogenerated carriers has been significantly improved. Theoretical calculations indicate that TiO_2−x exhibits significant selectivity towards H₂O on the (001) crystal plane. A series of experiments have verified the high efficiency of TiO_2−x in separating hydrogen isotopes under illumination conditions. When the ratio of H₂O to D₂O is 10 : 90, the yield of H₂ reaches 10.96 mmol g⁻¹ h⁻¹, and the H/D separation coefficient is 5.31. This study achieves selective catalysis and separation of hydrogen isotopes by selecting appropriate catalytic materials, providing a powerful supplement to traditional hydrogen isotope separation methods.