Porous graphitic carbon nitride with high concentration of oxygen promotes photocatalytic H2 evolution

Porous structure design and the content regulation of heteroelements have been proved to be effective strategies to boost photocatalytic H2 generation activity of graphitic carbon nitride (g-C3N4) based photocatalyst. Herein, a series of porous graphitic carbon nitride with high concentration of oxygen (g-C3N4-O) photocatalysts were synthesized via in situ polymerization process using colloidal SiO2 as oxygen source. The content of oxygen within the g-C3N4-O photocatalysts could be tuned by adjusting the amount of added colloidal SiO2 during the preparation procedure. The introduced oxygen replaced two-coordinated nitrogen atom, influencing band edge position and localized electron distribution, thereby enhancing visible light harvesting and photoelectric conversion. As a result, the g-C3N4-O photocatalyst with an optimal oxygen content (8.39 wt%) showed 10.5 fold enhancement in H2 evolution rate compared to that of bulk g-C3N4, attributed to the porous structure and high concentration of incorporated oxygen.