Enhanced photocatalytic performance of ammonia self-etched holely g-C3N4 decorated with anatase nanoflakes by a facile synthesis process

Abstract

Graphitic carbon nitride (g-C3N4) nanosheets have attracted extensive attention in the field of photocatalysis due to their superior properties. However, the photocatalytic performance of g-C3N4 is still restricted by the limited active sites and high combination rate of photo-generated carriers. To confront these drawbacks, a facile NH3 self-etching and TiO2 decorating method is employed in this work. The self-released NH3 with high concentration in thermal condensation process etches and exfoliates g-C3N4 into less aggregated nanosheets with abundant nano holes (~2.7 nm). The specific surface area is up to 224 m2·g−1, which is higher than the previous reported samples prepared by template-free methods. The formed holes endow g-C3N4 nanosheets with more exposed active edges that greatly accelerate mass exchange and photo-generated carriers transfer. After decorating anatase TiO2 nanoflakes, the composite photocatalyst exhibits a Z-scheme heterojunction behavior and enhances spatial separation efficiency of photo-generated carriers greatly. As a result, the photocatalytic performance is significantly enhanced: the photodegradation rate on rodamine B reaches 99.2% within 8 min and the hydrogen evolution rate reaches as high as 1764 μmol·g−1·h−1. This work provides a facile and low-cost processing method to prepare high active and stable photocatalysts, and show the importance in rational designing the nano-materials by well-directed preparation process and energy band engineering.