Porous and Few-Layer Carbon Nitride Nanosheets via Surface Steam Etching for Enhanced Photodegradation Activity

Two-dimensional polymeric carbon nitride (PCN) is a promising semiconductor for photocatalytic redox reactions. Herein, we report a straightforward, scalable, and low-cost production approach to prepare porous and few-layer PCN nanosheets by a steam etching of pristine bulk PCN that was attained from thermal polymerization of guanidinium thiocyanate. By optimization of the supplied amount of water steam, reaction temperature, and time of the steam etching process, the obtained porous and few-layer PCN nanosheets showed drastically increased photocatalytic activity with a hydrogen evolution rate of 0.658 mmol·g–1·h–1, which is 18.3-fold higher than that of pristine bulk PCN (0.036 mmol·g–1·h–1). They also exhibit an outstanding activity and a high stability for the degradation of dyes under visible-light irradiation. Moreover, the proposed steam etching method can also be expanded to other guanidinium precursor salts for the preparation of their corresponding porous and few-layer PCN nanosheets. As such, the steam etching strategy may stand out as an extremely simple method to prepare porous and few-layer PCN nanosheets with remarkably enhanced photocatalytic performances.