A structurally aligned nickel oxide encapsulated polypyrrole nanocomposite for hydrogen peroxide sensing

Abstract

A chemically responsive and structurally aligned nickel oxide encapsulated polypyrrole nano-composite (NiO-en-PPy) has been prepared using intrinsically functionalized pyrrole monomers by in situ polymerization and composite formation techniques under optimized conditions. The prepared samples were characterized by FT-IR spectroscopy, Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermal gravimetric analysis. Thus, the obtained results revealed the formation of the nanocomposite with aligned crystallinity, an interactive surface, improved electrical conductivity by 10³ times, and better thermal stability than those of pristine polypyrrole due to in situ functionalization and structural synergism between nickel oxide and pyrrole molecules. Furthermore, a spin-cast film of the prepared NiO-en-PPy composite on ITO coated glass was explored for the electrochemical sensing of hydrogen peroxide in liquid and the gas phase by monitoring the change in the resistance and potential. The observed sensing parameters in the gaseous and liquid state were sensitivity 22.7 Ω ppm⁻¹ in gas and 92.25 μV ppm⁻¹ cm⁻² in liquid, response time 30s in gas and 150 s in liquid, recovery time 70s in gas and 20 s in liquid, and the limit of detection 0.073692 ppm in gas and 0.073649 ppm in liquid with a durability of 90 days. Furthermore, a sensing mechanism has also been explained based on the electroactive interaction between the evolved interactive Ni sites of the composite matrix and peroxide molecules along with the role of induced conductivity in the functionalized PPy chain. The finding reveals the advancements in functional materials science and the properties of PPy for its use in chemical responsive devices and biosensors, and in the non-enzymatic estimation of reactive peroxide oxygen species.