Novel N-doped ZnO and O-doped g-C₃N₄ heterojunction: Enhanced photocatalytic degradation and robust electrochemical biosensing of ascorbic acid

Abstract

ZnO and g-C₃N₄ are known for their potential in photocatalytic degradation and electrochemical applications, but their limited band gaps and electrical conductivity hinders performance. Doping is a strategy to modify these properties. This study reports the synthesis of nitrogen-doped ZnO (N-ZnO) and oxygen-doped g-C₃N₄ (OCN) nanocomposites using an in-situ hydrothermal process. Structural and compositional analysis confirmed successful synthesis, while FESEM and HRTEM revealed N-ZnO nanorods decorating OCN sheets. Optical analysis indicated a band gap of 2.54 eV, making the material active under visible light. The nanocomposites demonstrated 90 % photodegradation of methylene blue (MB) within 20 min, with a high rate constant (k = 0.1269 min⁻¹), facilitated by a Z-scheme heterojunction. The catalyst remained stable even after 5 cycles. Moreover, electrochemical biosensing of ascorbic acid (AA) showed a regression value of 0.9965 with high anodic current response and small limit of detection (LOD) value, underscoring the potential of nanocomposite material for commercial applications in both photocatalysis and diagnostics.