Environmentally Friendly Methodologies of Nanostructure Synthesis

Abstract

Environmentally friendly synthetic methodologies have gradually been implemented as viable techniques in the synthesis of a range of nanostructures. In this work, we focus on the application of green-chemistry principles to the synthesis of complex metal oxide and fluoride nanostructures. In particular, we describe advances in the use of the molten-salt synthetic methods, hydrothermal protocols, and template-directed techniques as environmentally sound, socially responsible, and cost-effective methodologies that allow us to generate nanomaterials without the need to sacrifice sample quality, purity, and crystallinity, while allowing control over size, shape, and morphology.

Carbon nanotubes prepared by anodic aluminum oxide template method

“…In this method, the template simply serves as a structural framework within which carbon material can be generated by carbonization from precursors in situ and shaped into a nanostructure with its morphology dictated by the size and shape of the template scaffold [43]. For the synthesis of CNTs, porous AAO film is an ideal choice for templating, because of their parallel and straight channels, highly uniform distribution of cylindrical pores arranged in a hexagonal array, and tunable pore length, diameter and interpore distance.…”

“…Therefore, CNTs provide nanoscale space for loading foreign matters inside their hollow cores. The filled materials may show intriguing properties [43,109,110] due to the space confinement effect and the interactions with the surrounded carbon layers. On the other hand, the nanochannel of CNTs provides ideal delivery vehicles for the payloads of biomolecules, drugs, DNA, and metals [39].…”

Synthesis of BaZrO₃ nanocrystals by wet chemical reaction

“…1(b). BaZrO 3 was mainly obtained, but BaCO 3 and ZrO 2 were also observed. SEM observations revealed the formation of BaZrO 3 cubes.…”

“…The wet chemical reaction method is important in the synthesis of functional ceramics [2,3]. There are many techniques, such as the hydrothermal method, the solvothermal method, and the sol-gel method [4][5][6][7][8][9][10].…”

“…There are many techniques, such as the hydrothermal method, the solvothermal method, and the sol-gel method [4][5][6][7][8][9][10]. In particular, the composite-hydroxide-mediated (CHM) approach is a unique technique that uses the strong base of anhydrous hydroxides [11][12][13][14][15][16]. The CHM approach is based on chemical reactions involving materials in a eutectic hydroxide melt at low temperatures under ambient pressure in the absence of organic dispersants or capping reagents.…”