Confinement of MOF etching-induced hollow heterostructured cages in the carbon framework for efficient peroxymonosulfate activation

Abstract

Reducing the dissolution of metal nanocatalysts to preserve active catalytic sites for peroxymonosulfate-activated advanced oxidation processes (AOPs) is crucial for advanced wastewater treatment. On this basis, a well-defined hollow cage structure (H-CoS/NC)/nanoreactor was successfully constructed by the in situ assembly etching technique to promote the degradation of organic pollutants. The as-obtained catalysts played a significant role in reducing the dissolution of metal catalysts (0.46–0.65 mg L⁻¹) and phenol (50 mg L⁻¹) degradation achieved 100% within 30 min. The unique hollow structure allowed for higher instantaneous concentrations of organic pollutants in the microenvironment, thus providing the impetus for higher reaction rates. The mutual support and mesoporous adsorption of carbon shells allowed most of the CoS particles to be confined in the carbon framework without releasing them into the bulk solution, which improved the stability and reduced the dissolution of metal catalysts. In addition, the cavities between the hollow structures reduce the mass diffusion resistance making the enriched reactant molecules easier to contact with the active sites, which increases the contact of the reactants with the active sites, and realizes the ultra-fast pollutant degradation. This provides an effective way to reduce the dissolution of cobalt-based catalysts and retain active sites in AOPs, balancing the contradiction between the reactivity and stability of nanocatalysts.