Facing the issues for ineffective visible light utilization, insufficient separation of photogenerated electron-hole pairs of WO3 photoanode, herein, ultrasmall MoS2 quantum dots (QDs) are exploited as surface sensitizers to boost the photoelectrochemical (PEC) properties of MoS2/WO3. The MoS2/WO3 photoanode is prepared by decorating 2D WO3 nanoplatelet arrays with ultra-small MoS2 QDs via a facile and effective assembly method. The interspersing of MoS2 QDs, not only broadens the photoabsorption region, but also provides more active sites for the surface reactions and enhances charge separation of the photogenerated electron-hole pairs, leading to a 2.13-fold enhancement in photocurrent density at 1.0 V vs. Ag/AgCl (1.23 V vs. RHE). MoS2/WO3 photoanodes hold potentialities for the straightforward building of molecular level devices for PEC production. (C) 2017 Elsevier Ltd. All rights reserved.