Electrochemical determination of copper in seawater based on a patch-type integrated electrode modified with gold nanoparticle-decorated carbon nanoflowers

As both an essential trace metal nutrient and a heavy metal contaminant, copper (Cu) plays a significant yet dual role in marine ecosystems. Accurate determination of the labile fraction within dissolved Cu in the complex seawater matrix remains a major challenge. In this work, a novel electrochemical sensor based on a patch-type integrated electrode (P-tIE) modified with carbon nanoflowers (CNFs) and gold nanoparticles (AuNPs) was prepared for the determination of labile Cu in seawater. The three-dimensional flower-like structure of CNFs afforded a large specific surface area for loading AuNPs, which showed excellent electrocatalytic performance toward the voltammetric determination of Cu. Based on the synergistic effects of CNFs and AuNPs, the P-tIE sensor exhibited enhanced performance for Cu determination, exhibiting a linear range of 0.7-10 000 nM and a detection limit of 0.21 nM. Furthermore, the sensor was successfully applied to the direct determination of labile Cu in real seawater samples, providing a reliable tool for studies on the biogeochemical cycling of Cu in the ocean.