Rana Abu Ul Hassan Sarwar, Chang Seung-Bo, Kim Hyun-Seok
Division of Electronics and Electrical Engineering, Dongguk University-Seoul, Seoul 04620, South Korea.
J Nanosci Nanotechnol. 2018 Mar 1;18(3):2125-2127. doi: 10.1166/jnn.2018.14961.
We proffer NH4OH-oriented and pH-dependent growth of ZnO nanostructures via a microwaveassisted growth method. The fabrication of ZnO nanorods (ZNRs), nanoflowers (ZNFs), nanostars (ZNSs), and nanotetrapods (ZNTs) is presented. NH4OH was used as a mineralizer to change the solution pH for nanostructure growth, where temperature and other variables were fixed. Because of an efficient heat transfer and facile growth of nanostructures, a domestic microwave oven was used to facilitate the nanostructure growth in the span of just 10-15 min. The results showed that the growth of ZnO nanostructures was dependent upon the number of growth units and ZnO nuclei present in the solution, which ultimately depend upon the pH of the solution. At the outset, without the addition of NH4OH, the pH of the solution was ~6.8 and the ZNRs were formed in the solution or on a seeded substrate which persisted in the pH range of ~6.8-9. An abrupt change in the shapes and the types of the nanostructures was observed when the pH was boosted beyond 10. A transition from ZNRs to ZNFs was observed at pH 10 and ZNFs were formed at pH 11. The solution gave birth to ZNSs and ZNTs when the pH was further raised to 12 and 13, respectively.
我们通过微波辅助生长法实现了基于氢氧化铵（NH₄OH）和pH值依赖的氧化锌纳米结构生长。文中展示了氧化锌纳米棒（ZNRs）、纳米花（ZNFs）、纳米星（ZNSs）和纳米四脚架（ZNTs）的制备过程。NH₄OH被用作矿化剂来改变溶液pH值以促进纳米结构生长，同时固定温度和其他变量。由于高效的热传递和纳米结构的便捷生长，使用家用微波炉在短短10 - 15分钟内促进了纳米结构的生长。结果表明，氧化锌纳米结构的生长取决于溶液中生长单元和氧化锌核的数量，而这最终又取决于溶液的pH值。一开始，不添加NH₄OH时，溶液pH值约为6.8，在溶液中或有籽晶的基底上形成ZNRs，且在pH值约为6.8 - 9的范围内持续存在。当pH值升高到10以上时，观察到纳米结构的形状和类型发生突然变化。在pH值为10时观察到从ZNRs到ZNFs的转变，在pH值为11时形成ZNFs。当pH值进一步分别升高到12和13时，溶液中分别生成了ZNSs和ZNTs。
