Oxygen vacancies and interfaces enhancing photocatalytic hydrogen production in mesoporous CNT/TiO₂ hybrids

Abstract

We demonstrate a unique route towards hierarchical assemblies of mesoporous TiO₂ and CNT/TiO₂ photocatalysts by a combination of electrospinning and sol-gel methods. The resulting materials exhibit a mesoporous network of highly crystalline, well-connected inorganic nanocrystals with an order of magnitude higher photocatalytic activity than individualised TiO₂ nanoparticles. The in-situ combination of small amounts of MWCNTs with TiO₂ to form an electrospun CNT/TiO₂ hybrid further enhanced the oxide photoactivity considerably, reaching hydrogen evolution rates of 1218 μmol/h in water splitting in the presence of sacrificial reagents under UV irradiation. We also discuss the effect of oxygen vacancies on the oxide crystallisation and phase transformation. These vacancies lead to inter-bandgap states and a lower flat band potential that facilitates the photocatalytic process.