Enhanced optical and electrochemical properties MoO3-NiO-NiMoO4 ternary nanocomposite thin films: influence of PEG and PVA additives

In this study, a nanocomposite consisting of Molybdenum trioxide, nickel oxide, and nickel molybdate (MoO₃-NiO-NiMoO₄) was synthesized by the spin coating technique of sol-gel. We investigated the impact of polyethylene glycol (PEG) and polyvinylalcohol (PVA) on the physical properties of the nanocomposite through various analytical methods. XRD analysis revealed a composite structure consisting of the orthorhombic stable phase of MoO₃, the cubic phase of NiO, and the monoclinic of NiMoO₄ with an average crystallite size of between 39 and 58 nm. Furthermore, FESEM and AFM images indicated that surface morphology and roughness parameters changed dramatically with adding polymers. Interestingly, adding PEG and PVA polymers decreased refractive indices and extinction coefficients of prepared thin films, while the values of the band gap improved to 3.89 eV by adding PEG. Based on CV and GCD results, we found that PVA addition significantly enhanced the electrochemical performance of MoO₃-NiO-NiMoO₄ thin films, whereas PEG addition had minimal effects. The MoO₃-NiO-NiMoO₄/PVA nanocomposite exhibited the best performance at a current density of 0.1 mA cm^-2, with a specific capacity of 44.13 mF cm^-2. Moreover, MoO₃-NiO-NiMoO₄/PVA demonstrated a high capacity retention rate at a current density of 1 mA cm^-2, indicating a stability of 97.36% over 5000 charge/discharge cycles.