**2.3 Alternative synthesis methods**

Most of the methods of synthesis of nanomaterials allow a great flexibility in the choice of the precursors and the morphology of the material through the control of key parameters such as temperature, concentration, or pH. However, they also required the use of toxic chemical reactants or additives. In this regard, alternative synthesis routes have been exploited, with mitigated results, including biosynthesis, plasma assisted. Extraction from ores as for it fits in the strategy of valuation of naturally occurring ores.
