Enhanced photocatalytic activity by bulk trapping and spatial separation of charge carriers: A case study of defect and facet mediated TiO2

•Defect self-doped TiO2 with evolving explicit facets is facilely synthesized.•The separate roles of the defect and facet in photocatalytic reaction are revealed.•A synergistic effect between the defect and facet is demonstrated.•The activity of the co-mediated sample shows a 18 times enhancement than commercial TiO2.

Revealing the interplay between composition and structure of a given photocatalyst allows in-depth understanding of the photocatalytic mechanism and also presents as an effective way to optimise the photocatalytic activity. In this work, by studying the property and performance of defect and facet mediated rutile TiO2 synthesized via a facile oxidation reaction, we demonstrated that the abundant self-doped defects can not only render visiblie responce to the reduced TiO2 but also supress the prompt recombination of the charge carriers through bulk trapping, while the {1 1 1}–{1 1 0} facet couples can induce the spatial separation of the e–h pairs. A synergistic effect between the defects and the facets was observed in the co-mediated TiO2, and its performance of hydrogen liberation was enhanced by a factor of 18 under simulated solar light compared with referenced commercial rutile, consequently. The present work sheds new light on how the composition and structure of a material can be finely tuned and work synergistically to achieve a much boosted performance.

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