This contribution reports on the comparative synthesis and the main physical properties of ZnO NPs using green and chemical methods. A green approach was applied for synthesis of zinc oxide NPs for the first time using Nerium oleander flower extract as capping and reducing agent (ZnO–G). The chemical method was applied using sodium borohydride as reducing agent (ZnO–C). The green chemistry plant-based ZnO NPs are safer, energy efficient, eco-friendly, and less toxic than chemically synthesized counterparts. The characterization of ZnO–G and ZnO–C NPs was ascertained through Fourier Transform-Infrared (FT-IR), UV–Vis spectroscopy, X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), Thermal gravimetric and differential thermal analysis (TG–DTA). From the FT-IR spectra of ZnO NPs, the characteristic absorption peak of Zn–O bond was observed at 478 and 466 cm⁻¹ for ZnO–G and ZnO–C respectively. The shifted of Zn–O band due to the difference of bio-functional groups of N. oleander extract. Formation of nanoparticles was monitored using UV–Vis spectroscopy and a characteristic absorption peak for ZnO–G and ZnO–C was observed at 271 and 323 nm respectively. The XRD result for the ZnO shows the tendency of the three most intense diffraction peaks with crystalline structure of ZnO–C more than ZnO–G. The average crystallite size of ZnO–G and ZnO–C at scattering angle (2θ) 23.96 and 33.10 was 37.10 and 27.03 nm respectively. The EDX gave strong signals for zinc and oxygen indicating the occurrence of the nanoparticles in their oxide form rather than the pure zinc form. The SEM image shows the surface morphology of ZnO–G and ZnO–C displays a drastic modification of the surface morphology with the change of the synthesis method. Kinetic analyses of the ZnO thermal decomposition was calculated using Broido equation. This new eco-friendly synthesis of ZnONPs is a convenient technique for large scale commercial manufacture of ZnO NPs.

中文翻译：

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夹竹桃花提取物和化学方法合成ZnO纳米粒子及其物理表征的比较研究

该贡献报告了使用绿色和化学方法进行的ZnO NPs的比较合成和主要物理性质。绿色方法首次使用夹竹桃夹合成氧化锌NP花提取物作为加帽和还原剂（ZnO–G）。化学方法是使用硼氢化钠作为还原剂（ZnO–C）。基于绿色化学工厂的ZnO NP比化学合成的同行更安全，节能，环保且毒性更低。ZnO–G和ZnO–C NPs的表征通过傅里叶变换红外（FT-IR），UV-Vis光谱，X射线衍射（XRD），能量色散X射线光谱（EDX），扫描电子确定显微镜（SEM），热重分析和差热分析（​​TG-DTA）。从ZnO NP的FT-IR光谱中，分别观察到ZnO-G和ZnO-C在478和466 cm ^-1处的Zn-O键的特征吸收峰。Zn–O谱带的移动是由于夹竹桃提取。使用紫外-可见光谱法监测纳米颗粒的形成，并分别在271和323 nm处观察到ZnO-G和ZnO-C的特征吸收峰。ZnO的X射线衍射结果显示出三个最强衍射峰的趋势，其中ZnO–C的晶体结构比ZnO–G大。ZnO–G和ZnO–C在散射角（2θ）23.96和33.10处的平均微晶尺寸分别为37.10和27.03 nm。EDX发出强烈的锌和氧信号，表明纳米颗粒以氧化物形式而不是纯锌形式出现。SEM图像显示了ZnO–G的表面形态，而ZnO–C则随着合成方法的改变而对表面形态进行了大幅修改。使用Broido方程计算ZnO热分解的动力学分析。