Augmenting the catalytic performance of spinel nanoferrites (CoFe2O4 and NiFe2O4) via incorporation of Al into the lattice

Abstract

Spinel nanoferrites have emerged as outstanding catalysts for a variety of organic transformations and reactions. Spinel nanoferrites also possess the complementary benefit of facile and complete external magnet-aided recovery. Further improvement in the catalytic performance of spinel nanoferrites is currently a vibrant area of research. In this context, in the present investigation, Al has been incorporated into the lattice of spinel nanoferrites. Owing to its octahedral site preference, Al could actively participate in the reaction mechanism as octahedral sites are exposed upon the surface and catalytic activity is predominantly related to the metal ions present in these sites. Al content has varied from x = 0.2 to x = 1.0 when incorporated into the lattice of CoFe₂O₄ and NiFe₂O₄ as CoAl_xFe_2−xO₄ and NiAl_xFe_2−xO₄, respectively. Catalytic activity has been evaluated for the reduction of nitrophenols in the presence of NaBH₄ as the reducing agent. The catalytic activity has been found to increase with increasing Al content up to x = 0.6, before decreasing with further increase in Al content. The effect of increasing Al content on the catalytic performance is thought to be related to synergistic interactions among the metal ions present in the surface-exposed octahedral sites.