Structural and catalytic advancements in copper-substituted Mg-Zn spinel ferrites for DMAB-assisted nitroarene reduction
Materials Chemistry and Physics, cilt.368, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 368
- Basım Tarihi: 2026
- Doi Numarası: 10.1016/j.matchemphys.2026.133020
- Dergi Adı: Materials Chemistry and Physics
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Chemical Abstracts Core, Chimica, Compendex, INSPEC, Academic Search Ultimate (EBSCO), Engineering Source (EBSCO)
- Anahtar Kelimeler: Copper substitution, DMAB, Magnetic recyclability, Mg-Zn spinel ferrites, Nitroarene reduction
- İnönü Üniversitesi Adresli: Evet
Özet
This study presents the synthesis of copper-substituted Mg-Zn spinel ferrites (Mg0.1Zn0.9-xCuxFe2O4, x=0.0, 0.3 and 0.4) via an optimized sol–gel route and evaluates their performance as magnetically recoverable catalysts for the DMAB-assisted reduction of nitroarenes under mild aqueous conditions. Copper substitution markedly improves the catalytic response of the Mg–Zn ferrite system. The protocol avoids pressurized hydrogen and noble-metal catalysts, although the stoichiometric use of DMAB entails practical considerations related to reagent cost, waste generation, and safe handling. X-ray diffraction (XRD) confirmed the formation of a pure-phase cubic spinel structure. SEM and TEM observations revealed closely packed, quasi-spherical to irregularly rounded nanoparticles with inherent agglomeration; the SEM-derived average particle size increased from approximately 35.1 to 46.3 nm with increasing Cu content. In catalytic reduction reactions, the catalyst showed rapid conversion of nitrobenzene derivatives to the corresponding aniline derivatives, achieving the best yield in just 12 min with a 10 mol% catalyst loading. Room-temperature M − H measurements demonstrated that Cu substitution strongly enhances the magnetic response of the Mg–Zn ferrite system. The saturation magnetization increased from 6.49 emu g−1 for Cu0.0 to 43.35 emu g−1 for Cu0.3 and 49.9 emu g−1 for Cu0.4, while the coercivity remained low, increasing from 5.83 to 54.70 Oe across the same series. The low squareness ratio of Cu0.4, Mr/Ms = 0.103, indicates weak remanence and soft ferrimagnetic behavior, which is advantageous for magnetic separation and reuse because the catalyst can respond efficiently to an external magnet while limiting strong remanence-driven aggregation after field removal. This magnetic evolution is consistent with Cu-induced changes in cation distribution, A–B superexchange interactions, crystallite size, and magnetic anisotropy. The improved activity of the Cu-substituted ferrites is consistent with the greater contribution of Cu-containing ferrite surfaces to DMAB-assisted hydrogen transfer during nitroarene reduction. The Cu0.4 catalyst showed good short-term recyclability over six consecutive batch cycles, although the conversion gradually decreased to 85% in the sixth cycle. Because ICP-based leaching analysis and hot-filtration tests were not performed, the possible contribution of leached metal species cannot be ruled out, and the catalyst should be considered potentially leachable under the present reaction conditions. Overall, copper-substituted Mg–Zn ferrites represent a promising magnetically recoverable catalyst platform for nitroarene reduction, while further leaching, active-site, and mechanistic studies are required to confirm the true heterogeneous nature and long-term stability of the system.