Monolayer molybdenum disulfide (M-MoS2) nanosheets (NSs) have attracted tremendous attention owing to their extraordinary properties and extensive potential applications. However, the large-scale and cost-effective fabrication of uniform M-MoS2 NSs remains challenging. Herein, a novel space-confined synthesis strategy was developed for M-MoS2 NSs, using the interlayer spaces of layered double hydroxides (LDHs) as nanoreactors. The 2H-phase M-MoS2 NSs dispersed in water were obtained with a high production yield of similar to 98.7%, a quite high monolayer ratio of similar to 95%, a homogenous lateral size of similar to 89 nm, and a large monodispersed concentration of similar to 0.41 g L-1. The so-obtained M-MoS2 exhibits excellent electrocatalytic activity towards the hydrogen evolution reaction compared with bulk MoS2. This work provides an effective route for large-scale fabrication of two-dimensional transition-metal dichalcogenide nanomaterials. (C) 2019 Elsevier Inc. All rights reserved.