Synthesis and Characterization of ZnO Nanoparticles with Red Betel Leaf Extract (Piper crocatum) as a Capping Agent Using the Sonication Method

Abstract

The green synthesis of zinc oxide (ZnO) nanoparticles utilizing plant extracts offers an economical, non-toxic, and sustainable alternative to conventional chemical methods. This study comprehensively investigated the structural and optical optimization parameters by evaluating the effects of varying volume ratios of red betel leaf extract (Piper crocatum) to 0.1 M ZnSO4.7H2O precursor, alongside assessing the impact of alkaline pH variations. The entire synthesis procedure was assisted by ultrasound sonication for 30 minutes to enhance particle homogeneity and effectively prevent premature structural agglomeration. Optimization monitored through UV-Vis spectrophotometry revealed that the most optimal volume configuration was achieved at a 1:5 ratio, yielding the maximum specific absorption peak of 0.440 at a wavelength of 337.5 nm. Concurrently, pH 10 was determined to be the optimum alkaline condition, yielding a stable peak absorbance of 0.204 at 326 nm, driven by abundant hydroxyl (OH-) ions, which govern the rates of hydrolysis and nucleation. Structural characterization through X-Ray Diffraction (XRD) confirmed the formation of a pure hexagonal wurtzite crystal phase with high crystallinity, matching ICDD PDF No. 04-015-4060, revealing an average crystallite size of 30.5 nm. Fourier Transform Infrared (FTIR) analysis confirmed the characteristic Zn-O metal-oxygen stretching vibration at 423.22 cm-1, along with organic bands (O-H, C=O, and C-O), demonstrating that the extract phytochemicals functioned effectively as natural capping agents. Lastly, Particle Size Analyzer (PSA) testing confirmed a hydrodynamic particle size of 8.44 nm with a Polydispersity Index (PDI) of 0.1729, signifying monodispersed nanoparticles with excellent uniform distribution suitable for various advanced materials and surface-dependent technological applications.