Understanding of photochemical charge transfer processes at nanoscale heterojunctions is essential in developing effective catalysts. Here, we utilize a controllable synthesis method and a combination of optical absorption, photoluminescence, and electrochemical impedance spectroscopic studies to investigate the effect of MoS2 nanosheet lateral dimension and edge length size on the photochemical behavior of MoS2 -modified graphitic carbon nitride (g-C3 N4 ) heterojunctions. These nano-heterostructures, which comprise interlayer junctions with variable area (i. e., MoS2 lateral size ranges from 18 nm to 52 nm), provide a size-tunable interfacial charge transfer through the MoS2 /g-C3 N4 contacts, while exposing a large fraction of surface MoS2 edge sites available for the hydrogen evolution reaction. Importantly, modification of g-C3 N4 with MoS2 layers of 39±5 nm lateral size (20 wt % loading) creates interfacial contacts with relatively large number of MoS2 edge sites and efficient electronic transport phenomena, yielding a high photocatalytic H2 -production activity of 1497 μmol h-1 gcat -1 and an apparent QY of 3.3 % at 410 nm light irradiation. This study thus offers a design strategy to improve light energy conversion efficiency of catalysts by engineering interfaces at the nanoscale in 2D-layered heterojunction materials.
Keywords: MoS2; carbon nitride; nanostructures; photocatalysis; water splitting.
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