Inducing the Catalytic Activity in SrFe.sub.12O.sub.19 Via Chemical Modification

• Published in: Catalysis letters 2021-01, Vol.151 (1), p.221
• Main Authors: Anantharamaiah, P. N, Mondal, Sanjukta, Saha, Sujoy
• Format: Article
• Language: English
• ISSN: 1011-372X; 1572-879X
• DOI: 10.1007/s10562-020-03292-y

In this study, we demonstrate that the catalytic activity could be induced in the hard magnetic strontium hexaferrite (SrFe.sub.12O.sub.19) system by replacing a small fraction of Fe by Cu. Nanocrystalline SrFe.sub.12O.sub.19 and SrCu.sub.0.3Fe.sub.11.7O.sub.19 samples were synthesized by a tartrate-gel method and their structural, microstructural, specific surface area and magnetic properties were studies. Subsequently, the nanocrystalline hexaferrite powders were employed as catalysts to drive 4-nitrophenol reduction reaction using the NaBH.sub.4 as the reducing agent. The progress of the catalytic reactions was evaluated using UV-visible spectrophotometer. The unsubstituted sample was found to be catalytically inactive whereas SrCu.sub.0.3Fe.sub.11.7O.sub.19 sample showed superior catalytic performance in transforming 4-nitrophenol to 4-aminophenol within 8 min. Reusability test confirmed that the SrCu.sub.0.3Fe.sub.11.7O.sub.19 catalyst retains its 100% activity even after five consecutive cycles. In addition, the effect of crystallite size of SrCu.sub.0.3Fe.sub.11.7O.sub.19 on the catalytic reduction reaction of 4-nitrophenol was investigated. The results indicated that the time taken to complete the reduction reaction has been increased as size of the crystallites increased, probably due to decrease in the large number of surface active sites of the catalyst.