Template-free synthesis of mesh-like graphic carbon nitride with optimized electronic band structure for enhanced photocatalytic hydrogen evolution

Abstract

It is greatly significant to develop a facile strategy to optimize the nanostructure and chemical structure of graphic carbon nitride (GCN) for improved photocatalytic activity. In this work, a novel mesh-like GCN (MGCN) with tunable porous structure and condensation degree was successfully developed via a template-free strategy using supramolecular aggregate melamine cyanuric acid complex (MCA) as precursor. The as-obtained MGCN is endowed with more exposed active sites, narrower bandgap, higher electric conductivity, and greatly accelerate mass and photogenerated charge transfer, which are favorable for improving the efficiency of visible-light absorption, photogenerated carriers separation and interfacial redox reaction. Therefore, all the MGCN samples exhibit a superior performance in photocatalytic hydrogen evolution activity under visible-light irradiation. Furthermore, the hydrogen evolution rate (HER) of MGCN are enhanced with the increasing of calcination temperature. The optimum materials (MGCN-600) shows an excellent hydrogen evolution rate (~137.3 μmol h−1), which is up to 25 times higher than that of bulk GCN (BGCN), and with a remarkable apparent quantum efficiency (AQE) of 13.5% at 400 nm. This work provides a scale-up strategy in the design and synthesis of photocatalysts with controlled nanostructure and chemical structure for broad applications in photocatalysis.