Benzarti Zohra, Neiva Joana, Faia Pedro, Silva Eduardo, Carvalho Sandra, Devesa Susana
Centre for Mechanical Engineering, Materials and Processes (CEMMPRE)-Advanced Production and Intelligent Systems, Associated Laboratory (ARISE), Department of Mechanical Engineering, University of Coimbra, Rua Luís Reis Santos, 3030-788 Coimbra, Portugal.
Laboratory of Multifunctional Materials and Applications (LaMMA), Department of Physics, Faculty of Sciences of Sfax, University of Sfax, Soukra Road km 3.5, Sfax 3000, Tunisia.
Nanomaterials (Basel). 2025 Jun 26;15(13):991. doi: 10.3390/nano15130991.
This study presents a novel, eco-friendly synthesis route for zinc oxide (ZnO) nanoparticles using cladode extracts of acting simultaneously as reducing and improving agents, in alignment with green chemistry principles. The synthesis involved the reaction of zinc sulfate heptahydrate with the plant extract, with the medium pH adjusted using sodium hydroxide (NaOH), followed by calcination at 300 °C, 400 °C, and 500 °C, and then by a washing step to enhance purity. Comprehensive characterization was performed using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and electrical impedance spectroscopy to investigate the structural, morphological, and dielectric properties of the nanoparticles. The sample calcined at 400 °C, followed by washing (HT400W), exhibits highly crystalline ZnO nanoparticles with a predominant wurtzite structure (93.15 wt% ZnO) and minimal impurities (6.85 wt% NaSO). SEM analysis indicated a flake-like morphology with nanoscale features (50-100 nm), while Raman spectroscopy confirmed enhanced crystallinity and purity post-washing. Additionally, the HT400W sample exhibited a dielectric constant (ε') of 16.96 and a low loss tangent (tan δ) of 0.14 at 1 MHz, suggesting superior energy efficiency for high-frequency applications. This green synthesis approach not only eliminates hazardous reagents but also delivers ZnO nanoparticles with good dielectric performance. Furthermore, this work demonstrates the efficacy of a sustainable biotemplate, offering an environmentally friendly approach for synthesizing ZnO nanoparticles with tailored physicochemical properties.
本研究提出了一种新颖的、生态友好的氧化锌（ZnO）纳米颗粒合成路线，该路线使用 的叶状枝提取物同时作为还原剂和改良剂，符合绿色化学原则。合成过程包括七水硫酸锌与植物提取物的反应，使用氢氧化钠（NaOH）调节介质pH值，然后在300°C、400°C和500°C下煅烧，接着进行洗涤步骤以提高纯度。使用热重分析（TGA）、差示扫描量热法（DSC）、X射线衍射（XRD）、拉曼光谱、扫描电子显微镜（SEM）、能量色散X射线光谱（EDS）和电阻抗光谱进行全面表征，以研究纳米颗粒的结构、形态和介电性能。在400°C煅烧后再进行洗涤的样品（HT400W）呈现出高度结晶的ZnO纳米颗粒，具有主要的纤锌矿结构（93.15 wt% ZnO）且杂质极少（6.85 wt% NaSO）。SEM分析表明其具有纳米级特征（50 - 100 nm）的片状形态，而拉曼光谱证实洗涤后结晶度和纯度有所提高。此外，HT400W样品在1 MHz时的介电常数（ε'）为16.96，损耗角正切（tan δ）较低，为0.14，表明其在高频应用中具有卓越的能量效率。这种绿色合成方法不仅消除了有害试剂，还提供了具有良好介电性能的ZnO纳米颗粒。此外，这项工作证明了可持续生物模板的有效性，为合成具有定制物理化学性质的ZnO纳米颗粒提供了一种环境友好的方法。
