Facile oxalic acid-assisted construction of laminated porous N-deficient graphitic carbon nitride: Highly efficient visible-light-driven hydrogen evolution photocatalyst

The laminated porous N-deficient g-C3N4 (CNH) is successfully synthesized by a facile two-step hydrothermal calcination method using oxalic acid-assisted melamine as the precursor. Compared with pristine g-C3N4 (224 µmol g−1 h−1), the CNH shows superior photocatalytic hydrogen production activity (up to 728 µmol g−1 h−1), which is three times higher than the unmodified counterpart. To draw out the multifaceted influences of oxalic acid modification on the visible-light-induced photocatalytic activity, various techniques are utilized to investigate the formation mechanism, structural characteristics and photoelectrical properties of CNH. The results indicate that the addition of a trace amount of oxalic acid to the precursor melamine results in a g-C3N4 structure possessing the advantage of both nitrogen defects and laminated porosity. These properties can enlarge specific surface areas of g-C3N4, enhance an efficient separating of photogenerated electron-hole pairs and extend the range of spectral response, all contributing to the enhancement of the visible-light-induced photocatalytic activity.