Remarkably enhanced H₂ evolution activity of oxidized graphitic carbon nitride by an extremely facile K₂CO₃-activation approach

The photocatalytic activity enhancement of graphitic carbon nitride (g-C₃N₄) in water splitting were commonly achieved by introducing various functional groups onto/into its planar structure. Herein, oxidized g-C₃N₄ (CNO) was prepared via an extremely facile K₂CO₃ activation approach. The high-resolution XPS spectra and solid-state ¹³C NMR spectra confirmed the successful introduction of O-containing groups and O atoms were inherited the original molecular framework of g-C₃N₄, but exhibited effectively enlarged bonded with C atoms rather than N atoms in the tri-s-triazine structure of g-C₃N₄. CNO inherited the original molecular framework of g-C₃N₄, but exhibited effectively enlarged surface area and enhanced visible light absorption, and more attrractively, the band structure of g-C₃N₄ could be well-tuned with the introduction of oxygen species. Importantly, the surface O-containing moieties could strongly interact with cocatalyst Pt and thus remarkably promote interfacial electron transfer and consequent photo-generated charge carrier separation. Consequently, the as-obtained CNO exhibited the remarkably enhanced photocatalytic performance with a H₂ evolution rate of 199.7 μmol h⁻¹, which is 9 times that of g-C₃N₄ (22.2 μmol h⁻¹).