Fabrication of Carbon-Based Electrochemical Sensor Derived from Waste Coconut Husk for Dopamine Detection in Human Urine

Metals, particularly precious and transition metals, have traditionally been utilized in the fabrication of electrochemical sensors. Despite significant progress, challenges remain, such as the risk of metal ions leaching out and the potential for the catalyst to separate from its support. Acid oxidation is a well-known process for treating and enhancing carbon materials for use in a wide range of applications. However, its potential to directly improve the performance of electrochemical sensors has not been fully explored. The present work highlights the fabrication of a metal-free electrochemical sensor based on carbon material derived from acid oxidation of waste coconut husk, which introduced more oxygen-containing functional groups. The acid-treated coconut husk was further modified by high-temperature pyrolysis to introduce nitrogen and sulfur heteroatoms. The electrochemical behavior of the fabricated sensor was assessed using cyclic voltammetry and linear sweep voltammetry for the detection of dopamine. The sensor displayed a LOD of 0.6 μM and a wide linear range (0.24–3.38 μM). In addition, the selectivity, stability, and reproducibility (3.09%) of the sensor were satisfactory. These findings suggest the promising potential of carbon materials as an effective platform for the development of ultra-sensitive point-of-care devices for monitoring human healthcare.