Phenyl-modified carbon nitride nanosheets: Enhanced photocatalytic activity via sonication-assisted exfoliation

Semiconductor-based photocatalysis represents a valuable approach for sustainable environmental remediation and the production of clean energy. Polymer semiconductors represent an environmentally friendly, metal-free and low-cost option as a photocatalyst material. Among others, graphitic carbon nitride (g-C₃N₄) is one of the most promising materials due to its excellent chemical and thermal stability, as well as its layered structure that facilitates effective charge separation. However, the performance of bulk graphitic carbon nitride (g-C₃N₄) is often limited by poor visible-light absorption and low specific surface area. In the present study, to address these limitations, phenyl-modified carbon nitride (PhCN) was synthesised and subjected to extended liquid-phase exfoliation via ultrasonication, leading to an increased specific surface area and enhanced exposure of active sites. Compared to its bulk counterpart, the exfoliated PhCN exhibited significantly improved photocatalytic performance, enhanced dye degradation rates for Rhodamine B and Methylene Blue in commercial white LED, confirmed mechanism by scavenger tests, and demonstrated a 1.6-fold increase in hydrogen evolution over the bulk under solar simulator. The improvement in photocatalytic activity in the test reactions is primarily assigned to reduced electron-hole recombination facilitated by structural surface defects. The present study highlights the potential of ultrasonicated PhCN for efficient visible-light-driven photocatalytic applications.