Division of Nanomaterials and Chemistry, Hefei National Laboratory for Physical Sciences at the Microscale, Collaborative Innovation Center of Suzhou Nano Science and Technology, Department of Chemistry, CAS Center for Excellence in Nanoscience, Hefei Science Center of CAS, University of Science and Technology of China , Hefei 230026, China.
ACS Nano. 2016 Mar 22;10(3):3823-34. doi: 10.1021/acsnano.6b00704. Epub 2016 Mar 7.
The unsaturated "dangling" bonds on the surface of nanomaterials are extremely sensitive to the external environment, which gives nanomaterials a dual nature, i.e., high reactivity and poor stability. However, studies on the long-term effects of stability and reactivity of nanomaterials under practical conditions are rarely found in the literature and lag far behind other research. Furthermore, the long-term effects on the stability and reactivity of a nanomaterial without coating under practical conditions are seriously long-neglected. Herein, by choosing copper nanowire as an example, we systematically study the stability of copper nanowires (CuNWs) in the liquid and gas phase by monitoring the change of morphology, phase, and valence state of CuNWs during storage. CuNWs exhibit good dispersibility and durable chemical stability in polar organic solvents, while CuNWs stored in water or nonpolar organic solvents evolve into a mace-like structure. Additionally, fresh CuNWs are oxidized into CuO nanotubes with thin shells by heating in air. The activation energies of oxidation of CuNWs in the gas phase are determined by the Kissinger method. More importantly, the different oxidation pathways have significant effects on the final morphology, surface area, phase, optical absorption, band gap, and vibrational property of the oxidation products. Understanding the stability and reactivity of Cu nanostructures will add value to their storage and applications. This work emphasizes the significant issue on the stability of nanostructures, which should be taken into account from the viewpoint of their practical application.
纳米材料表面的不饱和“悬键”对外界环境极其敏感，这使纳米材料具有双重性质，即高反应性和差稳定性。然而，文献中很少有关于纳米材料在实际条件下稳定性和反应性的长期影响的研究，远远落后于其他研究。此外，对于实际条件下没有涂层的纳米材料的稳定性和反应性的长期影响，人们严重忽视了。在这里，我们选择铜纳米线作为一个例子，通过监测铜纳米线在储存过程中形态、相和价态的变化，系统地研究了铜纳米线（CuNWs）在液相和气相中的稳定性。CuNWs 在极性有机溶剂中表现出良好的分散性和持久的化学稳定性，而储存在水或非极性有机溶剂中的 CuNWs 则演变成狼牙棒状结构。此外，新鲜的 CuNWs 在空气中加热会氧化成具有薄壳的 CuO 纳米管。通过 Kissinger 法确定了 CuNWs 在气相中氧化的活化能。更重要的是，不同的氧化途径对氧化产物的最终形态、表面积、相、光吸收、带隙和振动特性有显著影响。了解 Cu 纳米结构的稳定性和反应性将为它们的储存和应用增添价值。这项工作强调了纳米结构稳定性的重要问题，从实际应用的角度来看，应该考虑到这一问题。
