Enhanced photocatalytic activities of g-C3N4 with large specific surface area via a facile one-step synthesis process

Abstract

Graphitic carbon nitride (g-C3N4) has been considered as a promising metal-free catalyst for a wide range of application due to its intriguing properties. However, the photocatalytic performance is restricted by the small specific surface area (SSA) and limited active sites. Here, a facile one-step method was employed to prepare thin porous g-C3N4 with large SSA by condensation of urea. During the pyrolysis process, the self-generated NH3 not only participates in the condensation reaction to obtain bulk g-C3N4, but also etches crystal lattice to form thinner nanosheets. A high SSA of 141.4 m2 g−1 for the sample synthesized in the enclosed condition (ECD-CN) is obtained, which is much larger than the SSA of 57.4 m2 g−1 for the sample synthesized in the non-enclosed condition (NCD-CN). These porous nanosheets with the enhanced SSA endow g-C3N4 more exposed active sites and shorten the carrier diffusion length. As a result, the ECD-CN sample exhibits much higher photodegradation rate on rodamine B (99.0% within 10 min) and hydrogen evolution rate (504.2 μmol h−1 g−1) under visible-light. This study provides a facile and template-free strategy in preparing efficient, sustainable and visible-light-driven photocatalyst.