Heterogeneous semiconductor has received increasing attention as promising photoelectrode matrix in photoelectrochemical (PEC) water splitting. However, the composition and optimization of heterostructure still limited the photoelectric transformation and PEC water splitting efficiencies. Here, an effective strategy was introduced to enhance PEC performance by sandwiching Au plasmon inside inorganic-organic hybrid heterostructure. We successfully fabricated TiO2 and polythiophene (PTh) heterostructure bridged by Au nanoparticles, and applied it in PEC water splitting for the first time. Compared with traditional TiO2 and TiO2/PTh, the as-prepared heterostructure photoelectrode exhibited the optimal photoelectric conversion (0.11%, at 0.22V vs Ag/AgCl) and PEC hydrogen production rate (2.929 mmol h(-1) m(-2), at 50 mW/cm(2) and 0.4V vs Ag/AgCl). The enhanced water splitting can be mainly contributed to the transparent PTh nanowires as the photosensitizer and Au nanoparticles as both electron-transport bridge and plasmonic sites. (C) 2016 Elsevier B.V. All rights reserved.