Enhanced photoelectrochemical performance of the hierarchical micro/nano-structured TiO2 mesoporous spheres with oxygen vacancies via hydrogenation

Hierarchical micro/nano-structured TiO2 mesoporous spheres with oxygen vacancies have been fabricated via a template-free strategy followed by hydrogenation and their photocatalytic performance has been explored. The hierarchical micro/nano-structured mesoporous spheres can act as a model architecture for efficient photoelectrochemical devices because they can simultaneously offer abundant catalytically active sites, excellent light-scattering characteristics and a highly conductive pathway for charge carriers collection. More importantly, oxygen vacancies are introduced onto the surface of TiO2 and function as shallow donors. The presence of oxygen vacancies not only boosts the light absorption but also improves the electrical conductivities of TiO2, thus enhancing the optical response and electron-hole separation. As a result, hierarchical micro/nano-structured TiO2 mesoporous spheres with oxygen vacancies exhibit a remarkably enhanced photoelectrochemical performance.