Magnetic amphiphilic nanocomposites produced via chemical vapor deposition of CH4 on Fe–Mo/nano-Al2O3

•Production of amphiphilic composites via catalytic CVD with nano-alumina and CH4.•Use of Fe and Mo catalysts for the growth of carbon nanostructures during CVD.•Combination of a hydrophilic matrix with a partial hydrophobic carbon coating.•Composites act as emulsifiers and demulsifiers due to be amphiphilic and magnetic.•Composites catalyze biphasic reactions, especially oxidation of organics with H2O2.

Catalytic chemical vapor deposition (CVD) using methane as carbon source was used to produce amphiphilic magnetic nanocomposites from Fe and Mo catalysts supported on alumina nanoparticles. The materials were reduced by hydrogen up to 900 °C and after were partially coated by carbon during a CVD process with CH4 also up to 900 °C. TPR results showed that the Fe and Mo phases present in the composites were reduced mainly to Fe0, Mo0 and iron carbide that consequently confers interesting magnetic properties to the materials. The materials produced with different Fe/Mo contents show saturation of magnetization between 1.1 and 28.1 emu g−1. Thermal analyses, CHN, Raman spectroscopy, SEM, TEM, EDS and BET showed that the higher the metal content, the more carbon was deposited on the materials. Carbon content of the materials varies from 2 to 16% and it is distributed mainly as nanotubes and nanofibers. These composites present excellent interaction on the interface between oil and water and are able to form emulsions as well as to break other stable emulsions. This feature is strategic to these composites as catalysts to act on the interface of biphasic systems. Preliminary studies of the materials as catalysts on biphasic oxidation of lipophilic dye Sudan-IV showed very promising results.

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