SnO 2 nanosheet SnO 2 –TiO 2 core shell Self-powered Photoelectrochemical UV photodetector a b s t r a c t We have fabricated SnO 2 nanosheet film directly on conductive glass and further designed branched TiO 2 nanoneedles on SnO 2 nanosheets, forming a heterojunction core–shell structure. The resultant ultrathin and high transparency film can serve as the fast electron transport network for a new developed photo-electrochemical cell based UV photodetector. The UV photodetector shows great responsivity (0.6 A/W); high on/off ratio of the J sc signal (440,563%); very fast response (0.02 s for rise time and 0.004 s for decay time) under 40 mW cm À2 UV irradiation. Compared with the previous reported devices, our detector emerges comparable and even better self-powered UV light detecting properties just using less material. Ó 2014 Elsevier B.V. All rights reserved.