Clark Ian, Smith Jacob, Gomes Rachel L, Lester Edward
Advanced Materials Research Group, Faculty of Engineering, University of Nottingham, University Park, Nottingham NG7 2RD, UK.
Food, Water, Waste Research Group, Faculty of Engineering, University of Nottingham, University Park, Nottingham NG7 2RD, UK.
Nanomaterials (Basel). 2020 Oct 16;10(10):2052. doi: 10.3390/nano10102052.
Core-shell Zinc Oxide/Layered Double Hydroxide (ZnO@LDH) composite nanomaterials have been produced by a one-step continuous hydrothermal synthesis process, in an attempt to further enhance the application potential of layered double hydroxide (LDH) nanomaterials. The synthesis involves two hydrothermal reactors in series with the first producing a ZnO core and the second producing the MgAl-CO shell. Crystal domain length of single phase ZnO and composite ZnO was 25 nm and 42 nm, respectively. The ZnO@LDH composite had a specific surface area of 76 m g, which was larger than ZnO or MgAl-CO when produced separately (53 m g and 58 m g, respectively). The increased specific surface area is attributed to the structural arrangement of the MgAl-CO in the composite. Platelets are envisaged to nucleate on the core and grow outwards, thus reducing the face-face stacking that occurs in conventional MgAl-CO synthesis. The Mg/Al ratio in the single phase LDH was close to the theoretical ratio of 2, but the Mg/Al ratio in the composite was 1.27 due to the formation of ZnAl-CO LDH from residual Zn ions. NaOH concentration was also found to influence Mg/Al ratio, with lower NaOH resulting in a lower Mg/Al ratio. NaOH concentration also affected morphology and specific surface area, with reduced NaOH content in the second reaction stage causing a dramatic increase in specific surface area (> 250 m g). The formation of a core-shell composite material was achieved through continuous synthesis; however, the final product was not entirely ZnO@MgAl-CO. The product contained a mixture of ZnO, MgAl-CO, ZnAl-CO, and the composite material. Whilst further optimisation is required in order to remove other crystalline impurities from the synthesis, this research acts as a stepping stone towards the formation of composite materials via a one-step continuous synthesis.
核壳结构的氧化锌/层状双氢氧化物（ZnO@LDH）复合纳米材料是通过一步连续水热合成法制备的，旨在进一步提高层状双氢氧化物（LDH）纳米材料的应用潜力。该合成过程涉及两个串联的水热反应器，第一个反应器生成ZnO核，第二个反应器生成MgAl-CO壳。单相ZnO和复合ZnO的晶畴长度分别为25nm和42nm。ZnO@LDH复合材料的比表面积为76m²/g，分别大于单独制备的ZnO或MgAl-CO（分别为53m²/g和58m²/g）。比表面积的增加归因于复合材料中MgAl-CO的结构排列。设想血小板在核上成核并向外生长，从而减少了传统MgAl-CO合成中发生的面对面堆积。单相LDH中的Mg/Al比接近理论值2，但由于残余Zn离子形成ZnAl-CO LDH，复合材料中的Mg/Al比为1.27。还发现NaOH浓度会影响Mg/Al比，较低的NaOH会导致较低的Mg/Al比。NaOH浓度也会影响形态和比表面积，第二反应阶段NaOH含量的降低会导致比表面积急剧增加（>250m²/g）。通过连续合成实现了核壳复合材料的形成；然而，最终产物并不完全是ZnO@MgAl-CO。产物包含ZnO、MgAl-CO、ZnAl-CO和复合材料的混合物。虽然为了从合成中去除其他结晶杂质还需要进一步优化，但这项研究是通过一步连续合成形成复合材料的垫脚石。
