Atomic defects in ultra-thin mesoporous TiO2 enhance photocatalytic hydrogen evolution from water splitting

Defects engineering is a promising and versatile method to improve solar-light-driven photocatalytic activity of photocatalysts. Mesoporous materials possess a versatile defective structure as well as a large exposed surface, which are particularly important in photocatalysis. Still, the underlying impact of defects in mesoporous photocatalysts remains elusive, as limited studies detail the exact atomistic surface structure and how the concentration of defects is directly related to the photocatalytic activity. Here, we successfully synthesized ultra-thin mesoporous-structured anatase TiO2 and changed the overall concentration of defects by improving the crystallinity. Without Pt deposition, the highest H-2 production of similar to 3.507 mmol h(-1)g(-1) was obtained under simulated solar light. We interrogated the atomic structure using scanning transmission electron microscopy, which directly revealed the coexistence of the lattice distortions and point defects in the mesoporous TiO2. Improving the crystallinity in TiO2 reduced these defects and slightly enhanced the H-2 yield from water splitting, while the charge-transfer resistance increased. Further introduction of Ti3+ atomic defects decreased the charge-transfer resistance and facilitated the separation of electron-hole pairs in the photocatalysis. This study offers inspiration for designing efficient photocatalysts and provides valuable insights towards defect engineering in photocatalysts.