Electron-Delocalized Cu²⁺ Activates Spin Channels in Spinel Oxides to Selectively Produce ¹O₂ for Wastewater...

Blocked electron transfer in the catalyst during advanced oxidation processes causes sluggish singlet oxygen (¹O₂) generation efficiency and sacrifices catalyst stability. In this work, we propose an electron-delocalization strategy that unlocks A_Td ²⁺─O─B_Oh ³⁺ electron-transfer pathways within spinel oxide (Cu_0.8Fe_2.2O₄), inducing the intermolecular electron transfer of peroxymonosulfate (PMS) for selective ¹O₂ generation. In situ characterizations and theoretical calculations confirm that the electron-delocalized Cu²⁺ triggers a high spin-state of O in Fe_Td ²⁺─O─Fe_Oh ³⁺, thus creating a spin channel for the spontaneous intermolecular electron transfer of PMS from the Fe_Oh ³⁺ adsorption site to the Fe_Td ²⁺ adsorption site through Fe_Td ²⁺─O─Fe_Oh ³⁺. This process allows for the simultaneous oxidation and reduction of PMS, thereby reducing the energy barriers for the formation of SO₄ ^•- and SO₅ ^•- radicals. Subsequently, the interfacial SO₄ ^•- rapidly oxidizes SO₅ ^•- into ¹O₂, enhancing ¹O₂ generation efficiency without sacrificing catalyst stability. The selectivity of ¹O₂ in the Cu_0.8Fe_2.2O₄/PMS system reaches 98.4%. Multiple pollutants are removed in the Cu_0.8Fe_2.2O₄/PMS system without interference from coexisting substances. The scale-up experiment realizes 100% contaminant removal during the continuous operation process (48 h). This work exhibits a novel strategy for selective ¹O₂ generation to achieve the goal of practical applications.