Enhancing deep visible-light photoelectrocatalysis with a single solid-state synthesis: Carbon nitride/TiO₂ heterointerface

Visible-light responsive, stable, and abundant absorbers are required for the rapid integration of green, clean, and renewable technologies in a circular economy. Photoactive solid–solid heterojunctions enable multiple charge pathways, inhibiting recombination through efficient charge transfer across the interface. This study spotlights the physico-chemical synergy between titanium dioxide (TiO₂) anatase and carbon nitride (CN) to form a hybrid material. The CN(10%)-TiO₂(90%) hybrid outperforms TiO₂ and CN references and literature homologs in four photo and photoelectrocatalytic reactions. CN-TiO₂ achieved a four-fold increase in benzylamine conversion, with photooxidation conversion rates of 51, 97, and 100 % at 625, 535, and 465 nm, respectively. The associated energy transfer mechanism was elucidated. In photoelectrochemistry, CN-TiO₂ exhibited 23 % photoactivity of the full-spectrum measurement when using a 410 nm filter. Our findings demonstrate that CN-TiO₂ displayed a band gap of 2.9 eV, evidencing TiO₂ photosensitization attributed to enhanced charge transfer at the heterointerface boundaries via staggered heterojunction type II.