Preparation of Main-group and Transition metal Graphenic Nano-composites for Energy Application

Abstract

Materials in nano-dimensions show intriguing properties that have led to a wide range of applications from medicine to device fabrications. In my thesis work, I have focussed in developing synthetic methodology for main-group nano-materials under relatively benign reaction conditions. The synthesized nano-materials have been tested for anode performance in lithium ion battery.

In the first chapter, carbon nano-sheets have been prepared from organosilicon reagents using a very facile approach. The synthesized carbon nano-sheets have been characterized using powdered X-ray diffraction techniques, Raman spectroscopy, X-ray photoelectron spectroscopy, FT-IR and elemental analysis. The microstructures have been studied using FE-SEM, HRTEM and AFM techniques. These graphenic carbons with very high nitrogen content show very good lithium ion battery anode performance.

In the second chapter, Ge-graphitic nano-composites have been coherently prepared under hot-injection conditions. This is the first report of simultaneously synthesizing Ge(0) nanocrystals and graphitic carbon in the solution-phase. The concurrent growth has led to the strong anchoring of Ge nanocrystals onto the graphitic carbon sheets. Ge has a very high theoretical capacity of 1600 mAhg-1 and hence is much coveted for constructing high energy density lithium ion battery. However, Ge is not commercially popular as it suffers from huge volume expansion during lithiation/delithiation process. In our nano-composite, the graphitic carbon helps to buffer the volume expansion to some extent. The detailed study of lithium ion battery anode performance of the Ge-graphitic nanocomposite has been done.

In the third chapter, Sb-graphitic nano-composite has been synthesized. The anode performance of this nano-composite has been studied for both lithium ion and sodium ion batteries. Although literature report suggests that the Sb is reputed for sodium ion battery anode application, in our case, we did not obtain reasonably good battery data. The lithium ion battery data is rather very promising.

In the fourth chapter, Co-graphitic nano-composite has been prepared. The utility of combining Co nano-crystals along with graphitic carbon has been studied for application in hydrogen evolution reaction.