Ngnintedem Yonti Cedrik, Kenfack Tsobnang Patrice, Lontio Fomekong Roussin, Devred Francois, Mignolet Eric, Larondelle Yvan, Hermans Sophie, Delcorte Arnaud, Lambi Ngolui John
Inorganic Chemistry Department, University of Yaoundé I, Yaoundé 812, Cameroon.
Institute of Condensed Matter and Nanosciences, Catholic University of Louvain, Croix du Sud, B-1348 Louvain-la-Neuve, Belgium.
Nanomaterials (Basel). 2021 Oct 25;11(11):2833. doi: 10.3390/nano11112833.
In this study, a bio-derived precipitating agent/ligand, palm kernel oil, has been used as an alternative route for the green synthesis of nanoparticles of Fe-doped CoO via the co-precipitation reaction. The palm oil was extracted from dried palm kernel seeds by crushing, squeezing and filtration. The reaction of the palm kernel oil with potassium hydroxide, under reflux, yielded a solution containing a mixture of potassium carboxylate and excess hydroxide ions, irrespective of the length of saponification. The as-obtained solution reacts with an aqueous solution containing iron and cobalt ions to yield the desired metallo-organic precursor, iron cobalt carboxylate. Characterization of the precursors by IR and gas chromatography (GC) attests to the presence of carboxylate fatty acids in good agreement with the proportion contained in the oil, and ICP confirms that the metallic ratios are in the proportion used during the synthesis. Analysis of the products thermally decomposed between 400 °C and 600 °C by XRD, EDX, TEM and ToF-SIMS, established that cobalt iron oxide nanoparticles (CoFe)O were obtained for x ≤ 0.2 and a nanocomposite material (CoFe)O/FeO for x ≥ 0.2, with sizes between 22 and 9 nm. ToF-SIMS and XRD provided direct evidence of the progressive substitution of cobalt by iron in the CoO crystal structure for x ≤ 0.2.
在本研究中，一种生物衍生的沉淀剂/配体——棕榈仁油，已被用作通过共沉淀反应绿色合成铁掺杂氧化钴纳米颗粒的替代途径。棕榈油是通过对干燥的棕榈仁种子进行粉碎、挤压和过滤而提取的。无论皂化时间长短，棕榈仁油与氢氧化钾在回流条件下反应，都会生成一种含有羧酸钾和过量氢氧根离子混合物的溶液。所得到的溶液与含有铁离子和钴离子的水溶液反应，生成所需的金属有机前体——铁钴羧酸盐。通过红外光谱（IR）和气相色谱（GC）对前体进行表征，证实了羧酸盐脂肪酸的存在，这与油中所含比例高度吻合，电感耦合等离子体质谱（ICP）则证实了金属比例与合成过程中使用的比例一致。通过X射线衍射（XRD）、能量色散X射线光谱（EDX）、透射电子显微镜（TEM）和飞行时间二次离子质谱（ToF-SIMS）对在400℃至600℃之间热分解的产物进行分析，结果表明，当x≤0.2时，获得了钴铁氧化物纳米颗粒（CoFe）O，当x≥0.2时，获得了一种纳米复合材料（CoFe）O/FeO，其尺寸在22至9纳米之间。对于x≤0.2，ToF-SIMS和XRD提供了铁在CoO晶体结构中逐渐取代钴的直接证据。
