Engineering Active Sites via Strong Metal-Support Interaction for Enhanced Catalysis on Hydroxyapatite-Supported Transition Metals

Abstract

The strong metal-support interaction (SMSI) significantly influences the catalytic performance of supported metal catalysts, yet achieving an optimal balance between high activity and long-term stability through support design remains a challenge. In this study, transition metal nanoparticles (Mn, Fe, Cu) were engineered onto substituted hydroxyapatite (HAP) via an ionexchange method to tailor the SMSI. The resulting M@HAP catalysts exhibited exceptional activity in peroxymonosulfate (PMS) activation, achieving phenol degradation rates of 94.7%, 99.3%, and 99.9% within 20 minutes for Fe@HAP, Cu@HAP, and Mn@HAP, respectively. Notably, Mn@HAP showed a kinetic rate constant 11.4-20.7 times higher than those of conventional metal oxides. Characterization results confirmed that the ion-exchange process led to the homogeneous dispersion of metal nanoparticles and the formation of a strong SMSI, which not only stabilized the metal species against leaching but also promoted efficient redox cycling between metal valence states. Mechanistic investigations revealed that the degradation process was primarily driven by radical pathways (SO₄•⁻ and •OH), supplemented by a non-radical (¹O₂ and electron transfer) pathway in Mn@HAP/PMS system. This work demonstrates that rational regulation of SMSI in mineralsupported catalysts provides a viable strategy for designing highly active, stable, and practical catalysts for environmental remediation.