Helianthus-annuus assisted synthesis of ZrO2 nanoparticles: Enhanced electrochemical, photoluminescent, and optical properties

Cubic-phase ZrO₂ nanoparticle (NPs) were synthesized using a cost-effective single-pot green combustion method and Helianthus annuus extract, and their properties were evaluated. Powder X-ray diffraction was used to investigate the purity, crystal structure, and size of the NPs, and the average size of the NPs was determined to be ∼ 25 nm. The internal surface morphology of the NPs with distinct voids and pores were observed using scanning electron microscopy (SEM) Ultraviolet–visible (UV-vis) absorption spectroscopy was used to analyze the optical properties of the as-synthesized ZrO₂ NPs, and their energy bandgap was determined to be 4.5 eV. The photoluminescence (PL) spectrum of the cubic-phase ZrO₂ NPs presented a broad band in the UV-vis region. The PL emission properties of the ZrO₂ NPs were studied by analyzing their emission wavelength at ∼490 nm, and the results revealed that the NPs can be efficiently used for display applications. The electrochemical properties of a graphite–ZrO₂ NP electrode was qualitatively analyzed by performing cyclic voltammetry (CV) and electrochemical impedance spectroscopy experiments in a three–electrode system with a 0.1 M KCl solution as the electrolyte. Our results suggested that the NPs can be used to evaluate the thermodynamics of the redox reaction, and their capacitance was determined using the CV curves of a graphite–ZrO₂ working electrode at different scan rates in the range of 0.01 ∼ 0.05 V/s at room temperature. Furthermore, the photodegradation rate of Reactive Blue 4 textile dye over the as-prepared ZrO₂ NPs reached 97% under UV-vis light irradiation.