Fenton-like reaction via combining confinement effect and Lewis acid-base reaction inside a nanoreactor

In Fenton-like reaction, the pollutant degradation performance was closely related to the peroxymonosulfate (PMS) activation activity. As a Lewis base, PMS activation could be accelerated by either Lewis acid-base reaction, or the high local concentrations. To simultaneously realize two aims, herein, a nanoreactor was prepared, where SO₄²⁻ modified Co₃O₄ nanoparticles were encapsulated inside Co₂SiO₄ shell. The Lewis acidity on Co³⁺/Co²⁺ catalytic sites was improved with the help of SO₄²⁻ possessed powerful electron attraction, leading to a rapid Lewis acid-base reaction. Under the confinement effect, both PMS and generated reactive oxygen specie concentrations were boosted inside the cavity, resulting in a rapid transformation of SO₄^•‐+^•OH to ¹O₂. Benefiting from two advantages, metronidazole degradation efficiency over nanoreactor at 16.0 min was 92.2%, mineralization efficiency was 68.9%, PMS activation efficiency was 44.0%, and PMS utilization efficiency was 67.2%, much higher than the reference catalysts. Meanwhile, the leached cobalt ion concentration was only 0.48 mg/L, lower than samples without Co₂SiO₄ shell protection. This work provided a novel way to engineer catalyst surface property inside a nanoreactor, and realized Fenton-like reaction acceleration via combination of confinement effect and Lewis acid-base reaction.