Cobalt-doped graphitic carbon nitride photocatalysts with high activity for hydrogen evolution

Cobalt-doped graphitic carbon nitride (Co CN) was synthesized by one-step thermal polycondensation using cobalt phthalocyanine (CoPc) and melamine as precursors. The π-π interaction between melamine and CoPc promotes cobalt doping into the framework of g-C 3 N 4 . The prepared samples were carefully characterized and the results demonstrated that Co-doped graphitic carbon nitride inhibited the crystal growth of graphitic carbon nitride (CN), leading to larger specific surface area (33.1   m 2   g −1 ) and abundant Co-N x active sites, narrower band gap energy and more efficient separation of photogenerated electrons and holes. 0.46% Co CN exhibited higher hydrogen evolution rate (28.0   μmol   h −1 ) under visible light irradiation, which is about 3.0 times of that over the pure CN and about 2.2 times of that over cobalt-doped CN using CoCl 2   ∙   6H 2 O as a cobalt source. This study provides a valuable strategy to modify CN with enhanced photocatalytic performance.