Visible light active titanoniobate nanosheets for efficient photocatalytic H2 production from water.

Ultrathin titanoniobate nanosheet co-doped with Cr/Nb have been fabricated which show superior photocatalytic activity for H 2 production from water under both full range (λ ≥ 250 nm) and visible light illumination (λ ≥ 400 nm). • Titanoniobate nanosheets with thickness of a few nanometers have been prepared. • Cr/Nb co-dopants can be introduced into these nanosheets. • Cr/Nb modified nanosheets own a large surface area and visible light sensitivity. • Nanosheets show superior photocatalytic activity for H 2 production. • Dopants Cr at the surface may serve as catalytic reactive sites. Titanoniobate nanosheets with thickness down to a few nanometers have been prepared by ion exchange and subsequent exfoliation treatment on a bulk layer compound KTiNbO 5. Superior photocatalytic H 2 production activity has been realized on these nanosheets, surpassing their mother compound KTiNbO 5. More interestingly, their photocatalytic activity has been successfully extended into visible light region when Cr/Nb co-dopants are introduced into nanosheets. The Cr/Nb modified nanosheets show apparent quantum efficiency as high as 2.75% at 420 ± 20 nm for H 2 production, outperforming a number of doped metal oxides photocatalysts. Such high photocatalytic activity origins from their tiny thickness and a much enlarged surface area that favors charge separation and transfer. Their little dependence on cocatalyst for H 2 production suggest that dopants Cr may also serve as catalytic reaction sites as a substantial fraction of Cr dopants are accommodated at the surface. This facile approach to fabricate ultrathin 2D semiconductor as well as versatility of doping strategy open new playground for the design and development of efficient visible light active photocatalysts. [ABSTRACT FROM AUTHOR]