Facile preparation with high yield of a 3D porous graphitic carbon nitride for dramatically enhanced photocatalytic H2 evolution under visible light

For its performance enhancement, graphitic carbon nitride (CN) has been prepared by acid protonation or heat etching methods, both with quite low product yield. In the present work, three dimension porous CN was prepared in a facile way with high yield by both operation of acid protonation and thermal oxidation. It was found that the CN subjected to firstly acid protonation and secondly heat etching (CN-HT) exhibited almost 29.5 times higher H2 evolution rate compared to the pristine CN. While the sample subjecting to a reverse operation sequence only had 7.3 times improvement. Compared to the re-calcined sample without protonation, it was found that the introduction of protons (H+) into CN structure before re-calcination significantly enhanced its activity for visible light driven photocatalytic H2 generation. After full characterizations, the significantly enhanced activity was attributed to the greatly enlarged surface areas, the promoted charge carriers separation and immigration efficiency, the improved reduction potential of photo-induced electrons, as well as the strengthened hydrophilic interface. Our study is expected to provide a new facile approach for tailoring the microstructure of layered materials to achieve improved performance not only for the application of photocatalysis, but also in many other fields.