A facile plant and chemical-mediated mechanosynthesis of α-Fe₂O₃ nanoparticles

Mechanochemical reactions are highly favourable owing to their efficiency and require less or no solvents for extraction and synthesis, agreeing with green chemistry principles. Here, we explore the formation of iron(iii) oxide nanoparticles using a chemical base and/or plant material in neat and liquid-assisted grinding (LAG). Interestingly, nanorods were formed by neat grinding, whilst LAG resulted in spherical-like nanoparticles when the chemical base was used. Using Artemisia afra as a base instead of chemical base, ultra small nanoparticles were produced showing spherical-like shape by neat grinding and polyhedral shape by LAG reaction. The morphological observation also revealed that changing the metal precursor to iron sulphate or iron nitrate influences the shape of nanoparticles formed to hexagonal and spherical-like, respectively. The conditions of the mechanochemical approach employed to synthesise iron oxide nanoparticles confirmed the production of a hematite (α-Fe₂O₃) polymorph. The mechanosynthesis protocol presents a green approach for producing new and/or existing materials at a shorter reaction time and ambient conditions in comparison to other conventional methods reported.