Morphologically Controlled Synthesis of Reduced-Dimensional ZnO/Zn(OH)2 Nanosheets.

Conventional two-dimensional materials either have natural layered structures or are produced, with large surface areas, via physical or chemical synthesis. However, to form a two-dimensional material from a non-layered material, a method different from the existing ones is required. In this study, a surfactant-assisted method was utilized to synthesize Zn(OH)2 (a nonlayered transition metal oxide) nanosheets. This study described the synthesis of Zn(OH)2 nanosheets using an anionic sulfate layer and demonstrated a method of controlling the thickness and shape of the synthesized nanosheets by varying the surfactant concentration. Further, the characteristics of oxygen evolution reaction using ZnO/Zn(OH)2 nanosheets, obtained by annealing the synthesized sheets, as catalysts were studied.

In-situ formation of co particles encapsulated by graphene layers.

The process of encapsulating cobalt nanoparticles using a graphene layer is mainly direct pyrolysis. The encapsulation structure of hybrids prepared in this way improves the catalyst stability, which greatly reduces the leaching of non-metals and prevents metal nanoparticles from growing beyond a certain size. In this study, cobalt particles surrounded by graphene layers were formed by increasing the temperature in a transmission electron microscope, and they were analyzed using scanning transmission electron microscopy (STEM). Synthesized cobalt hydroxide nanosheets were used to obtain cobalt particles using an in-situ heating holder inside a TEM column. The cobalt nanoparticles are surrounded by layers of graphene, and the number of layers increases as the temperature increases. The interlayer spacing of the graphene layers was also investigated using atomic imaging. The success achieved in the encapsulation of metallic nanoparticles in graphene layers paves the way for the design of highly active and reusable heterogeneous catalysts for more challenging molecules.