Vacuum Condensation of Hybrid Polymeric Graphitic Carbon Nitride for Extended Visible-Light Photocatalytic Hydrogen...

Polymeric graphitic carbon nitride (g-CN) has attracted considerable attention as a promising photocatalyst; however, its practical application is still hindered by the poor visible-light absorption and rapid recombination of photoinduced charge carriers. Herein, we report a vacuum-condensation approach for synthesizing g-CN with a hybrid polymeric structure that contains melon-type chains combined with completely condensed domains, which induces a notable structural disorder with the N/C atomic ratio less than 1.5 (the nominal value of melon). This hybrid polymeric structure intrinsically extends the π-conjugated system of the heptazine-based framework, narrows its band gap, accelerates the exciton dissociation, and thus substantially improves its photocatalytic hydrogen evolution (PHE) performance. Compared to the counterparts synthesized under inert atmospheres (N₂ and Ar), the vacuum-polycondensed g-CN exhibits a threefold enhancement for visible-light-driven hydrogen production. In particular, its PHE activity can be effectively maintained under the light wavelength extended to 520 nm. This work presents a promising strategy to break through the limitation of linear polymerization pathway during the conventional g-CN synthesis and offers new opportunities for rational design of more efficient g-CN-based photocatalysts.