Mixed Titanium Oxide Strategy for Enhanced Photocatalytic Hydrogen Evolution

Abstract

Titanium dioxide is a promising photocatalyst material for water splitting, but is limited by its low utilization of solar energy and rapid recombination of electron-hole pairs. Herein, a mixed titanium oxide strategy, utilizing TiO₂/Ti₂O₃ heterostructures consisting of in situ grown TiO₂ nanotubes with mixed anatase and rutile phases on bulk Ti₂O₃ materials, is demonstrated for efficient and recyclable hydrogen evolution from photocatalytic water splitting. Taking advantage of the formed heterostructures and the created porous structures, the photogenerated electrons from the conduction band of anatase TiO₂ can be first delivered to rutile TiO₂ and then transferred to Ti₂O₃. Meanwhile, the presence of Ti₂O₃ in TiO₂/Ti₂O₃ heterostructures can substantially promote the charge mobility and suppress the recombination of photogenerated electron-hole pairs. Hence, with a tuned band gap structure that enables rapid electron-hole separation, increased charge carrier density, and enhanced light absorption, the TiO₂/Ti₂O₃ heterostructures provide an enhanced photocatalytic hydrogen evolution rate as high as 1440 μmol g^-1 h^-1 under full-sunlight irradiation and without any other cocatalyst. This mixed titanium oxide strategy may open up new avenues for designing and constructing highly efficient TiO₂-based photocatalytic materials for various applications.