Mechanochemical and Solvothermal Synthesis of Graphene Oxide and Graphite Nanocomposites with Lanthanides

Carbon is one of the most abundant elements in the Earth’s crust, where graphite and diamond are the most common in Nature. Over the past 2 decades, the fabrication of carbon-based nanomaterials has attracted the scientific community's attention devoted to developing materials with novel properties. Combining lanthanides with carbon-based nanomaterials is a pathway to hybrid materials with unique useful properties exploitable in fields like biomedicine, catalysis, and environmental remediation.
The synthesis of such materials via safer, more sustainable, and environmentally friendly synthesis routes and at a low cost is a current challenge. Therefore, this PhD project aimed to develop carbon-based nanocomposites with lanthanides following several principles of green chemistry, namely waste prevention, atom economy, less hazardous chemical synthesis, and safer solvents and auxiliaries. Our approach was to prepare graphene-lanthanide nanocomposites via two different routes, solvothermal synthesis and ball milling.
In a solvothermal process, a chemical reaction occurs in a sealed vessel at high pressures and temperatures (typically around 100 °C - and 200 °C). In the ball milling process, reactants in powder form are mixed in a jar, and ground with the help of metal balls. When the jar rotates, the balls pulverise the powders inside and the generated forces stimulate chemical reactions between the mixture's components and between powder(s) and atmosphere in the jar.
Both synthesis routes were demonstrated to be suitable eco-friendly approaches to obtaining graphene-lanthanide nanocomposites, but interestingly, the nanocomposites prepared by the solvothermal synthesis and by ball milling were found to behave very differently when interacting with cells; nanostructured materials generated by solvothermal synthesis exhibited with strong antibacterial activity, while those nanocomposites prepared by ball milling showed low cytotoxicity.