Green Synthesis of Cobalt Oxide Decorated Chitosan Substrates for Electrochemical Detection of Nitrite and Hydrogen Evolution Reactions

The Co₂O₃-Chitosan composite (Co@Chitosan) nanoparticles were synthesized through a green approach. The composite under investigation was characterized by various analytical methods, including scanning electron microscopy (SEM), transmitted electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and atomic force microscope (AFM) confirming the preparation step. The modified composite’s performance was evaluated for its potential applications in nitrite sensing and hydrogen production by utilizing diverse electrochemical methodologies. The Co₂O₃-Chitosan that has been modified exhibits a linear detection range of 0.25–100 µM and a limit of detection (LOD) of 0.117 µM with a response time of approximately 5 s using the amperometry technique. Furthermore, the utilization of Co₂O₃-Chitosan composite as a proficient catalyst for hydrogen generation in an alkaline environment was implemented. The electrode exhibited enduring stability in fuel generation and heightened energy safeguarding. The current density of the electrode was observed to attain a value of \(\upeta\) $\mathrm{\eta }$ ₅₀ at − 0.55 and − 0.43 V (versus RHE) for Co₂O₃ and Co@Chitosan, respectively. The study investigated the durability of electrodes during extended periods of constant potential chronoamperometry lasting 6 h. The Co₂O₃ and Co@Chitosan exhibited a reduction in initial current by 11% and 7%, respectively.