Study on the mechanism of two-dimensional heterostructured interlayer-confined catalysts for efficient PMS activation in antibiotic degradation: Interface engineering and 1O2 selective dominant pathway

Abstract

To address the low efficiency and poor stability of advanced oxidation processes (AOPs), we developed a MXene-supported multilayered nanoreactor through interfacial engineering. By leveraging a bimetallic ZIF-derived topological transformation, we carefully engineered the CoZn-LDH/MXene heterointerface. This resulted in a two-dimensional heterostructure catalyst (CZLDH-MXene) with enhanced catalytic performance and stability. This 2D heterostructure optimizes the activation pathway, accelerates reaction kinetics, and enhances environmental adaptability. These improvements address the current limitations of persulfate-based advanced oxidation systems, offering a more efficient solution. Electrons are transferred from the catalyst to peroxomonosulfate (PMS) through the dual channels of Ti(II)/Ti(III)↔Ti(IV) and Co(II) ↔ Co(III), forming a stable CZLDH-MXene-PMS* interface complex, which proves the effectiveness of electron transfer process II mechanism (ETP II mechanism). The CZLDH-MXene/PMS system achieved complete degradation of 20 mg/L oxytetracycline (OTC) within 10 min. It also demonstrated broad pH tolerance (4–10) and resistance to ion interference. Quenching experiments and electron paramagnetic resonance (EPR) spectroscopy confirmed that the 2D heterostructure shifted the reaction mechanism from a radical-based pathway (•OH/SO₄^•−) to a singlet oxygen (¹O₂)-dominated non-radical mechanism, with ¹O₂ contributing 84.2 % to the process. The continuous flow reactor developed in this study showed stable and dynamic removal of simulated wastewater for up to 5 h, maintaining >98 % efficiency. This innovation overcomes the limitations of traditional batch reactors. These findings highlight the potential of this approach for water pollution control and introduce a new paradigm in designing efficient heterogeneous catalysts.