Stable Ti³⁺ defects in oriented mesoporous titania frameworks for efficient photocatalysis

By introducing a compatible reducing agent (2-ethylimidazole) into a mono-micelle assembly process, we present a type of ordered mesoporous TiO₂ microspheres that combines radially aligned mesostructure with Ti³⁺ defects in mesoporous frameworks. Such reductant acts as a building block of mesostructured frameworks and reduces Ti⁴⁺ in situ to generate defects during calcination, giving rise to the coexistence of bulk Ti³⁺ defects and an ordered mesostructure. The mesoporous TiO₂ has both excellent mesoporosity (a high surface area of 106 m² g⁻¹, a mean pore size of 18.4 nm) and stable defects with an extended photoresponse. Such integration of unique mesoscopic architecture and atomic vacancies provide both effective mass transportation and enhanced light utilization, leading to a remarkable increase in H₂ generation rate. A maximum H₂ evolution rate of 19.8 mmol g⁻¹ h⁻¹ can be achieved, along with outstanding stability under solar light.