Cuo-Modified Graphitic Carbon Nitride as A Bifunctional Platform for Organic Pollutant Reduction and Plasmonic Detection of Cadmium İons

Abstract

In this study, the facile two-step synthesis of CuO-modified graphitic carbon nitride (CuO@g-C₃N₄) hybrid nanosheets with catalytic and sensing functions was carried out. Pristine g-C₃N₄, obtained by thermal polymerization of melamine, was surface-engineered with in-situ deposited CuO nanoparticles, resulting in a uniform nanocomposite with abundant active sites and enhanced electron-transfer capability. Structural (XRD), optical (UV–Vis), and morphological (SEM-EDS, TEM) characterizations confirmed the successful formation of a p–n heterojunction, a narrowed bandgap (from 2.55 eV to 1.84 eV), and a uniform distribution of CuO nanoparticles across the g-C₃N₄ layers. The hybrid material exhibited excellent catalytic activity for the NaBH₄-assisted degradation of methyl orange (MO) and acetamiprid (ACT), achieving rapid pollutant removal as described by pseudo-first-order kinetics. Furthermore, CuO@g-C₃N₄ demonstrated a pronounced bathochromic surface plasmon resonance (SPR) shift upon Cd2+ ion interaction, enabling its application as a plasmonic fluorescence sensor. Detection parameters revealed limits of detection (LOD) and quantification (LOQ) of 107.6 μM and 358.7 μM, respectively. While g-C₃N₄-based composites combining photocatalysis with sensing have been previously reported, to the best of our knowledge this is the first demonstration on a CuO@g-C₃N₄ platform that integrates NaBH₄-assisted catalytic reduction of an azo dye and a neonicotinoid pesticide in the dark with Cd2+ detection via an SPR-mediated fluorescence response, providing a cost-effective route for environmental remediation and monitoring.