超临界水热合成纳米氧化锌的动力学及聚乙烯吡咯烷酮耦合作用机理研究

Supercritical hydrothermal synthesis (SCHS) is an efficient and green technology for preparing advanced nano-powders, which can promote the development of high-quality nanoscale ZnO. In order to obtain the crystallization kinetics and surface modification mechanism of nanoscale ZnO during the SCHS process, this paper analyzes the crystallization kinetics curves driven by temperature and time to obtain information on the rates and activation energies of nanoscale ZnO in nucleation and growth processes. Additionally, polyvinylpyrrolidone (PVP) is used to modify ZnO surface in situ. By analyzing the morphology of zinc oxide synthesized under different PVP and KOH ratios, the coupling mechanism of PVP and KOH is determined. The results indicate that the activation energy of nanoscale is 603. 06 kj • mol ' during nucleation and 63. 1 0 kj • mol ' during growth, with more energy consumed in the nucleation stage than in the growth stage. Nanoscale ZnO particles with the smallest size are synthesized when the precursor, KOH, and PVP concentration ratio is 1 : 3 : 2, with an average particle size of 6. 9 nm. When the KOH to PVP concentration ratio is too high, excess PVP on the surface of ZnO nanoparticles leads to gel-like deposits, forming aggregates that result in an increase in the particle size of the synthesized nanoparticles.