Simultaneous nanostructure and heterojunction engineering of graphitic carbon nitride via in situ Ag doping for enhanced photoelectrochemical activity

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.