Interface engineering of Co₃O₄ via phosphate functionalization for boosted peroxymonosulfate activation toward...

Co₃O₄ stands out as a promising heterogeneous catalyst for peroxymonosulfate (PMS) activation to degrade aqueous organic pollutants. However, its relatively low catalytic efficiency greatly hinders practical wastewater remediation applications. Herein, we rationally construct phosphate-functionalized Co₃O₄ (PCO) catalysts via a facile impregnation-calcination surface engineering strategy to substantially enhance PMS activation efficiency by promoting PMS adsorption and interfacial electron transfer. Taking tetracycline (TC) as a representative antibiotic contaminant, the catalytic activity of PCO was systematically evaluated. Impressively, under optimal conditions (0.16 g/L catalyst, 1.8 mM PMS, 25 °C), the optimized PCO catalyst (0.5 M phosphate impregnation, 600 °C calcination) achieves 97.47% TC (30 mg/L, 250 mL) removal within 20 min. Radical scavenging experiments and electron paramagnetic resonance (EPR) spectroscopy verify the synergistic roles of •OH, •SO₄^-, •O₂^-, and ¹O₂ in TC degradation. Liquid chromatography-mass spectrometry (LC-MS) combined with toxicity prediction reveals that the toxicity of TC degradation intermediates is markedly attenuated. Density functional theory (DFT) calculations further confirm that phosphate modification reinforces PMS adsorption on the Co₃O₄ surface, accelerates interfacial electron transfer, and facilitates O-O bond cleavage in PMS, thus boosting catalytic performance. This work offers a unique and efficient surface modification approach for Co₃O₄-based PMS activators, highlighting its great potential for organic wastewater purification.