Elucidation of aCore–Shell Structure in Phenyl-GraftedCarbon Nitride/TiO₂ Nanohybrids for Visible-Light-MediatedH₂ Production with Simultaneous Rhodamine B Degradation

Dual-functional photocatalysts help to maximize resource utilization in water remediation, but often they are visible-light-inactive, toxic, and cost-intensive. Herein, a type-II heterojunction visible-light-active photocatalyst is reported for tandem degradation of Rhodamine B and generation of H₂. A Rhodamine B degradation rate of 2.3 × 10^–2 min^–1 and H₂ production activity of 5789 μmol h^–1 g^–1 are shown. The hybrid shows a gradient core–shell morphology with a visible - light-absorbing phenyl-modified carbon nitride (PhCN) core and a porous PhCN/TiO₂ outer shell, resulting in an enhanced interaction between the catalyst and the surroundings. The nanoscale crystallization of TiO₂ on PhCN’s surface, shifts the triazine network structure, while autoclave treatments further increase the band gap and suppress charge carrier recombination. The influence of nanoscale morphological changes on photocatalytic activity was examined by varying the component ratios and thermal treatments, highlighting the strong correlation between the nanoscale architecture and the enhanced catalytic activity. This work provides a detailed guide to the exploration of environmentally friendly dual-functional photocatalysts.