Titanoniobate nanosheets with thickness down to a few nanometers have been prepared by ion exchange and subsequent exfoliation treatment on a bulk layer compound laiNb0(5). Superior photocatalytic H-2 production activity has been realized on these nanosheets, surpassing their mother compound KTiNb0(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. (C) 2019 Elsevier Inc. All rights reserved.