Spin state regulated by asymmetric orbital hybridization in Ni-Fe2O3 to promote fenton-like catalytic activity

Abstract

The manipulation of spin states in metal active sites can significantly impact the energetics of peroxymonosulfate (PMS) molecule adsorption and bond dissociation, thereby exerting influence on the reaction pathway and kinetics. However, the optimization of Fe2O3 catalysts for PMS activation has overlooked spin-related electron transfer and orbital interactions. In this study, we propose a Ni-doping strategy to modify the spin state of Fe2O3 (Ni-Fe2O3) through asymmetrical orbital hybridization (Ni-O-Fe) to enhance PMS activation, with the aim of establishing a correlation between spin state and catalytic activity. The high-spin Ni-Fe2O3/PMS system exhibits a significantly higher reaction rate constant (0.20 min−1), approximately 2.85 times greater than that observed in the low-spin Fe2O3/PMS system (0.07 min−1). The asymmetrical orbital coupling induced by Ni doping enhances spin splitting and electron delocalization within the Ni-Fe2O3 catalyst, creating an efficient electron transfer channel between the high-spin catalyst and adsorbed PMS molecules. This enhanced electron transfer disrupts charge distribution in PMS and elongates OO bonds, leading to a significant enhancement in OH generation potential. The establishment of a correlation between high spin active sites and PMS activation provides valuable insights into the intelligent design of spin-regulated nanocomposites for advanced water purification.