Wet-chemistry hydrogen doped TiO2 with switchable defects control for photocatalytic hydrogen evolution

Abstract

<h2>Summary</h2> Hydrogen has a remarkably flexible chemistry in oxides. We show that the introduction of H into simple TiO₂ leads to greatly enhanced photocatalytic properties, and specifically yields a 60 times enhancement of photocatalytic hydrogen evolution activity over commercial rutile. The hydrogenated TiO₂ (H-TiO₂) is synthesized by a new one-step wet-chemistry approach yielding switchable defect via controlled annealing. As-prepared H-TiO₂ has Ti-H bonds in the lattice from replacement of oxygen by hydrogen atoms. The Ti-H bonds are converted to oxygen vacancies by loss of H₂O with Ar annealing. Oppositely, Ti-H defects are healed by Ti-O with O₂ annealing. The strongly enhanced photocatalytic activity is associated with increased visible light absorption and effective separation of photogenerated carriers. This work provides a new and powerful approach for the preparation of hydrogenated titanium dioxide with switchable defect control, and striking improvement of photocatalytic activity.