Graphitic carbon nitride (g-C3N4) is a promising heterogeneous photocatalyst for organics pollutants degradation and water splitting. Herein, we highlight an available pathway to prepare the ultrafine g-C3N4 nanosheets by gaseous stripping of bulk g-C3N4 in wet nitrogen. As comparison, g-C3N4 treated in air and nitrogen atmospheres are also prepared. The obtained products are characterized with X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and Fourier transform infrared spectra, respectively. Well dispersed g-C3N4 nanosheets can be obtained by this gaseous stripping process in wet nitrogen, which possess much higher specific surface area (211.2 m(2) g(-1)) than that of bulk g-C3N4 (15.3 m(2) g(-1)). Both RhB degradation and water splitting are applied to characterize the photocatalytic performances of the ultrafine g-C3N4 nanosheets. The g-C3N4 (w-N-2) nanosheets can degrade 20 mg/L RhB completely within 12 min under visible light illumination, which is 5.32 times faster than that of bulk g-C3N4. Also, the g-C3N4 (w-N-2) nanosheets possess the highest photocatalytic hydrogen evolution rate of 1113.48 mu mol h(-1) g(-1) under visible light illumination, which is 6 times that of bulk g-C3N4. The mechanisms of enhancing the photocatalytic performance are discussed to be the higher oxidation ability of VB and higher specific surface area (211.2 m(2)/g) of the ultrafine g-C3N4 nanosheets. (C) 2017 Elsevier B.V. All rights reserved.