Visible-light photocatalytic degradation of bisphenol A using cobalt-to-oxygen doped graphitic carbon nitride with nitrogen vacancies via metal-to-ligand charge transfer.

As an environmentally friendly and promising semiconductor, graphitic carbon nitride (g-CN) was widely used in photocatalytic treatment of aqueous organic pollutants. In this study, cobalt-to-oxygen doped graphitic carbon nitride with feeble nitrogen vacancies (Co-OCN) as metal-to-ligand charge transfer was synthesized via a facile thermal polymerization method with low cost and non-toxic precursors. The oxygen doped graphitic carbon nitride with feeble nitrogen vacancies (OCN) ligand was successfully formed and cobalt was presented in OCN in an ionic form (in the form of Co-N). The cobalt atoms were chemically coordinated to the OCN matrix rather than forming cobalt oxide on the surface of OCN. The embedded cobalt atoms maintained the absorption margin of ligand OCN (up to 700 nm) and served as the separation centers to promote the interfacial electron transfer as well. Due to the synergistic effects of the embedded cobalt atoms and oxygen doping, the Co-OCN showed an outstanding activity for the visible-light photocatalytic oxidation of endocrine disruptor bisphenol A (BPA).