Enhancing photocatalytic performance of Graphitic carbon nitride through deep eutectic system synthesis

Abstract

Graphitic carbon nitride (GCN) has emerged as a promising semiconductor for visible-light photocatalysis owing to its favorable electronic band structures and stability. However, conventional GCN materials face challenges such as limited light absorption and specific surface area. The choice of precursors significantly influences GCN properties. Mixing different precursors, such as urea and ammonium thiocyanate, in a deep eutectic system (DESys) enables the formation of a homogeneous liquid and the synthesis of GCN with unique structures, enhancing photochemical activity. Through adjustments to the DESys composition and synthesis conditions, the synthesis of GCN-DESys has been optimized, with the optimal conditions being a mixture of ammonium thiocyanate and urea at a ratio of 1:4, heated at 550 °C for 3 h. Characterization of GCN-DESys revealed a mixed layered and velvety structure, forming a heterojunction distinct from traditional GCN. With a degradation mechanism investigation, GCN-DESys demonstrated superior photocatalytic activity in degrading ciprofloxacin under visible light, outperforming traditional GCNs. GCN-DESys, synthesized through the new approach, shows outstanding photocatalytic performance owing to its unique structure and enhanced charge separation. Mechanism analysis revealed the pivotal involvement of hydroxyl radicals (·OH) and superoxide radicals (·O2–) in the photocatalytic degradation process. The formation of these radicals on the surface of the GCN-DESys contributes to the efficient degradation of ciprofloxacin. This study contributes to understanding the preparation of advanced photocatalytic materials through the formation of DESys-based liquid mixture, highlighting the potential of GCN-DESys as an efficient solution for pollutant degradation.