High-entropy engineering of spinel catalysts for nonradical catalytic ozonation with improved resistance to humidity and sulfur poisoning

Abstract

Conventional catalytic ozonation of electron-rich sulfur-containing pollutants shows limited efficiency due to nonselective oxidation of hydroxyl radicals (•OH) and sulfate-induced deactivation of active metal sites. Here, we synthesized a high-entropy spinel, (CuNiMnCo)Fe2O4, featuring sublattice-resolved electronic reconstruction that enables selective ozone activation and suppresses sulfur poisoning. The catalyst achieves 99% removal of methyl mercaptan (CH3SH), significantly outperforming 51% of CoFe2O4. Spectroscopic analyses and density functional theory calculations reveal that high-entropy doping induces lattice distortion and local coordination disorder, which strengthen A–O–B covalency and inter-site electronic communication. This structural perturbation further drives a sublattice-resolved electronic reconstruction, enriching Co/Mn sites while depleting Fe/Cu/Ni sites. This electronic differentiation promotes cooperative dual-end activation of O3 on Fe–Co/Mn motifs and preferential CH3SH adsorption on Cu/Ni sites. Orbital modulation of Co t2g and Fe eg states near the Fermi level balances interfacial charge transfer, favoring formation of a surface-bound *O3 species over conventional O–O bond cleavage. The resulting spatially separated activation and oxidation sites enable CH3SH mineralization via an electron transfer process while suppressing •OH generation and minimizing sulfate accumulation. This spatially differentiated reaction environment ensures durable performance under humid conditions. These findings establish sublattice-engineered electronic asymmetry as a strategy for selective catalytic ozonation. This study demonstrates that a high-entropy spinel separates ozone activation from methyl mercaptan adsorption, enabling efficient removal under humid conditions while reducing sulfate accumulation and sulfur poisoning.