Iron oxide nanoparticles have been intensively investigated owing to their huge potential as diagnostic, therapeutic, and drug-carrier agents in biomedicine, sorbents in environmental technologies, sensors of various inorganic and organic/biological substances, energy-generating and storing materials, and in assorted biotechnological and industrial processes involving microbiology, pigment industry, recording and magnetic media or (bio)catalysis. An eminent interest in exploring the realm of iron oxides is driven by their chemical and structural diversity, high abundance, low cost, non-toxicity, and broad portfolio of chemical procedures enabling their syntheses with desirable physicochemical features. The current review article centers its attention on the contemporary advancements in the field of catalysis and environmental technologies employing iron oxides in various chemical forms (e.g., hematite, magnetite, maghemite), sizes (∼10–100 nm), morphology characteristics (e.g., globular, needle-like), and nano architecture (e.g., nanoparticles, nanocomposites, core–shell structures). In particular, the catalytic applications of iron oxides and their hybrids are emphasized regarding their efficiency and selectivity in the coupling, oxidation, reduction, alkylation reactions, and Fischer–Tropsch synthesis. The deployment of iron oxides and their nanocomposites in environmental and water treatment technologies is also deliberated with their roles as nanosorbents for heavy metals and organic pollutants, photocatalysts, and heterogeneous catalysts (e.g., hydrogen peroxide decomposition) for oxidative treatment of various contaminants. The associated challenges and potential progress in iron-oxide-based catalytic and environmental technologies are highlighted as well. Young chemists, researchers, and scientists could find this review useful in enhancing the usefulness of nano iron oxides in their investigations and developing sustainable methodologies.
