Construction of sandwich structured photocatalyst using monolayer WS2 embedded g-C3N4 for highly efficient H2 production

The construction of sandwich structured binary composite can enlarge its specific surface and strengthen the contact of binary interface. This can enhance H2 generation efficiency of the photocatalyst. In this study, two-step strategy for the preparation of novel sandwich-structured g-C3N4/WS2 is proposed. Step one is hydrothermal process producing the layered WO3, which is used as the precursor for monolayer WS2. While step two involves one-pot calcination process that generates sandwich structured g-C3N4/WS2. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma optical emission spectrometry (ICP-OES), Brunauer Emmett Teller method (BET), and transmission electron microscopy (TEM) are employed to characterize the composition, structure and morphology of g-C3N4/WS2. Photocatalytic H2 generation tests show that the optimal H2 generation rate of g-C3N4/WS2 is 599.7 μmol h-1 g-1 (20 mg of photocatalyst), which is about 25 times higher than that of bare g-C3N4. Moreover, UV–vis diffuse reflectance spectroscopy (UV–vis DRS), photoluminescence (PL) and electrochemical tests are employ to establish possible mechanism of photocatalytic H2 evolution in sandwich-structured g-C3N4/WS2.