▎ 摘　　要

Nanosheet materials obtained from laminar compounds are new two-dimensional anisotropic nanomaterials that can even reach the sub-nanometer scale. These materials possess unique physical and chemical properties. An example of such a nanosheet materials is graphitic carbon nitride (g-C3N4) nanosheets transformed from bulk g-C3N4. Here, g-C3N4 nanosheets were prepared from bulk g-C3N4 by high-temperature thermal oxidation. The photocatalytic activity of eosin (EY)-sensitized g-C3N4 nanosheets for hydrogen evolution was about 2.6 times higher than that of bulk g-C3N4. The structure of the g-C3N4 nanosheets and process of electron transfer between EY and the g-C3N4 nanosheets were investigated by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) analysis, fluorescence spectroscopy, and photoelectrochemical measurements. The g-C3N4 nanosheets possessed high specific surface area. The g-C3N4 nanosheets not only effectively absorbed dye molecules, but also enhanced the separation and electron transport efficiencies of photogenerated charges because of their quantum confinement effect. The quantum confinement effect of g-C3N4 nanosheets widened their bandgap, improved electron transfer ability along the in-plane direction, and lengthened the lifetime of photoexcited charge carriers. As a result, the photocatalytic activity of the g-C3N4 nanosheets was improved compared with that of bulk g-C3N4.