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

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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.