Screen-Printed Carbon Electrode Modified by δ-MnO₂/S@g-C₃N₄ Nanocomposite for Dopamine Sensing Using Linear Sweep Voltammetry

In this paper, we report the hydrothermal synthesis of manganese dioxide (δ-MnO₂) and its composite with sulfur-doped graphitic carbon nitride (δ-MnO₂/S@g-C₃N₄). Advanced sophisticated physicochemical characterization techniques (powder x-ray diffraction [PXRD], scanning electron microscopy [SEM], energy-dispersive x-ray spectroscopy [EDS]) were adopted to verify and confirm the formation of the δ-MnO₂ and δ-MnO₂/S@g-C₃N₄. A dopamine (DA) sensor was fabricated by modifying the surface (active area) of the screen-printed carbon electrode (SPCE) using the δ-MnO₂/S@g-C₃N₄ composite as electrocatalyst. Good sensitivity of 1.53 µA µM⁻¹ cm⁻² was achieved using the δ-MnO2/S@g-C₃N₄-modified SPCE, and the device demonstrated a good limit of detection (LOD) of 1.12 µM. The δ-MnO₂/S@g-C₃N₄-modified SPCE also exhibited good stability, selectivity, and repeatability for the determination of DA. Furthermore, the δ-MnO₂/S@g-C₃N₄-modified SPCE exhibited good stability, repeatability, and selectivity for detecting dopamine using linear sweep voltammetry (LSV).