ZnO纳米片层结构的原位生长机理及热力学函数

In-situ Growth Mechanism and Thermodynamic Functions of ZnO Nanosheet Structures

采用绿色水介质体系一步合成了3种不同尺寸的ZnO纳米片层结构。通过微热量技术获取其原位生长过程的热谱曲线,从动力学和热力学角度分析其生长机理;利用电化学方法测定了不同温度下纳米ZnO与块体ZnO原电池的电势差,结合热力学基本公式求算出ZnO纳米片层结构的热力学函数值,并与生长机理关联讨论。结果表明,ZnO纳米片层结构的生长经历了先表观吸热后表观放热,放热减慢,最后到达放热平台的热量变化阶段。标准摩尔熵、标准摩尔生成Gibbs自由能及标准摩尔生成焓均随着尺寸减小而逐渐增大。本文为纳米材料的原位生长机理与热力学函数的关联研究提供了新的思路和方法。

Three different sizes of ZnO nanosheet structures were prepared in one step by using the green water reaction system at room temperature. Microcalorimetry was used to obtain the in-situ growth heat curves, whose thermodynamic information of growth can be recorded in-situ and the corresponding growth mechanism was discussed from the point of thermodynamics. In addition, the electromotive forces were performed by a primary battery assembled by applying the prepared uano-ZnO and purchased bulk ZnO onto the surface of two zinc electrodes under different temperatures. The thermodynamic functions of nano-ZnO were gained by combining with basic formula of thermodynamic and associated with the growth mechanism. The results reveal that the growth of the ZnO nanosheet structures undergoes three stages for heat change. The standard molar entropy, standard molar Gibbs free energy, and standard molar enthalpy are increased along with the decreasing particle size. This paper provides a new method for investigating the in-situ growth mechanism and the thermodynamic functions of nanomaterials.