Understanding Morphology-Controlled Synthesis of Zinc Nanoparticles and Their Characteristics of Hydrolysis Reaction

Abstract

Two-step thermochemical water-splitting cycle based on a Zn/ZnO redox pair is considered as a potential route for carbon-free production of hydrogen because the first hydrolysis step of the cycle highly depends on the method of preparation and the resultant particle characteristics, such as size, morphology, surface state, and initial oxide content. Here, employing a conventional evaporation and condensation method, we successfully produce three types of Zn nanoparticles ranging from nanorods, mesoporous nanorods with nanospheres on their surfaces, and fully sintered nanocrystals. The achievement in morphology control is realized simply by changing the injection position of the quenching gas. We found that the resultant hydrolysis kinetics is highly dependent on the morphology and porosity of the Zn nanoparticles. Finally, a series of simple mathematical modeling is made in an effort to understand the formation mechanism of Zn nanoparticles.