Ultrasound-Assisted Fabrication of Hierarchical Rodlike Graphitic Carbon Nitride with Fewer Defects and Enhanced Visible-Light Photocatalytic Activity

The catalytic performance of graphitic carbon nitride (g-C3N4) is significantly affected by its microstructure and intrinsic defects. Here, rodlike g-C3N4 (RCN) with hierarchical structure and fewer defects is fabricated through an ultrasound-assisted molecular rearrangement strategy. Rodlike supramolecular precursors are formed by rearrangement of melem through ultrasound in water. Heating the precursors at 550 degrees C leads to less defective hierarchical g-C3N4 composed of nanosheets. No expensive or hazardous reagent is involved in this process. The decrease in defects has been confirmed by powder X-ray diffraction, Fourier transform infrared, and X-ray photoelectron spectroscopy. The special hierarchical structure provides RCN with significantly increased surface area and enhanced efficiency of light harvesting. The decrease in defects broadens the visible-light responsive range, suppresses the recombination of electron hole pairs, and enhances the electric conductivity. The visible-light photocatalytic activities of RCN for RhB degradation and H-2 evolution increase 16.7- and 8.7-times, respectively, compared to that of bulk g-C3N4 prepared by directly heating melamine.