Stable Ti3+ Defects in Oriented Mesoporous Titania Frameworks for Efficient Photocatalysis.

Abstract

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.