Two-dimensional transition metal dichalcogenides (2D TMDs) and their heterostructures have by far stimulated growing research interests in the field of optoelectronics and photocatalysis. In this regard, scalable fabrication of 2D TMDs at an environmentally-benign and cost-effective manner via liquid phase exfoliation is a particularly fascinating concept. Herein we report a facile and green strategy to produce few-layered WS2 suspensions at a large scale by a direct exfoliation of commercial WS2 powders in water-ethanol mixtures. In turn, by making full use of the features of 2D layered WS2, a novel 2D WS2/MoS2 composite was constructed for the first time via an in-situ hydrothermal reaction to grow MoS2 nanoflakes onto few-layered WSZ basal planes. The as-obtained WS2/MoS2 heterostructure was investigated for photocatalytic applications. Such a hybrid material demonstrated superior photocatalytic activity in the photocatalysis of organic dye molecules relative to that of pristine 2D WS2, MoS2 and their physical mixtures. This enhancement was associated with the 2D WS2/MoS2 heterostructuring effect. In addition, comparisons of the photocatalytic performances of our heterojunctions with those of recently reported 2D TMD-based hybrid materials manifested a significantly higher efficiency. (C) 2017 Elsevier Inc. All rights reserved.