ZnO flowers consisting of single crystal nanosheets with exposed {1 (1) over bar 0 0) facets were fabricated from trisodium citrate via hydrothermal at 180 degrees C. The single crystal nanosheet has the thickness of about 70 nm and a well-crystalline structure with dominant surfaces as {1 (1) over bar 0 0) planes. The site-specific nucleation growth process contributes to the formation of hierarchical flower-like ZnO structures. The ZnO flowers exhibited white emission. The visible emission gradually decreased with time and the UV emission suggests that the recombined rate of photogenerated electrons and holes of samples varied with the synthesis parameters. The ZnO flowers displayed an enhanced photocatalytic performance compared with ZnO microspheres. The maximized exposure of the reactive {1 (1) over bar 0 0) facets also favors the enhanced photo catalytic performance. Additionally, the special loose structural feature with an open microstructure has more important influences on the photocatalytic activity than specific surface area. (C) 2016 Elsevier B.V. All rights reserved.