A novel mesoporous ternary photocatalyst consisting of g-C3N4 nanosheets, metallic silver and MoS2 nanosheets is prepared using AgNO3 as a multifunctional modifier during thermal polymerization of melamine and few-layer MoS2 in a simple one-pot process. The gas bubbles from AgNO3 form an extra soft templates to in situ alter the polymerization behavior of melamine, creating thin g-C3N4 nanosheets and large porous structure that exhibit enhanced light absorption. The solution-based, soft-chemical synthesis enables homogeneous inclusion of metallic silver in the g-C3N4 nanosheets and high dispersibility of ultrathin MoS2 nanosheets in the obtained nanocomposite. In situ coupling between metallic silver and g-C3N4 nanosheets produces nanoscale Mott-Schottky effect, provides an effective channel for charge separation and transfer, and tunes energy band of the latter. More importantly, modulated energy band of g-C3N4 nanosheets synergistically expedites the separation and transfer of photogenerated electron-hole pairs at the interface of two-dimensional g-C3N4/MoS2 heterojunction. As a result, the ternary nanocomposite exhibits improved photoelectrochemical performance and photocatalytic activity under simulated sunlight irradiation compared with other reference materials. Our results provide new insights into the design and large-scale production of semiconductor photocatalyst. (C) 2014 Elsevier B.V. All rights reserved.