Self-assembled materials from MXene and polyoxometalates based on polymerization of dopamine in one step for non-radical dominated degradation of sulfamethoxazole

Abstract

The difficulty in introducing polyoxometalates (POMs) into few-layer MXene (Ti₃C₂) is caused by POMs dissolution and the easy oxidation of MXene. In this paper, a ternary composite of MXene-SiW₉Co₃@PDA, was synthesized in a one-step process by the self-polymerization of dopamine (DA) on few-layer MXene. The material was characterized by a large MXene interlayer spacing, low dissolution of POMs, and high oxidation resistance with good adsorption properties, excellent stability, and catalytic activity. MXene-40 %SiW₉Co₃@PDA degraded 98 % of sulfamethoxazole (SMX) in 30 min with a pseudo-first-order rate constant k of 0.1401 min⁻¹. The redox of Ti²⁺/Ti³⁺ or Ti⁴⁺ in MXene and Co²⁺/Co³⁺ in POMs activated peroxymonosulfate (PMS), which generated large amounts of reactive oxygen species (ROS). As a consequence, the degradation of SMX was not dominated by SO₄⁻·, but by non-radical ¹O₂. Additionally, this system was also efficient in degrading norfloxacin (30 min, 94 %), amoxicillin (5 min, 99 %), and tetracycline hydrochloride (10 min, 95 %). This study provides a new idea in developing two-dimensional MXene-based POMs composites and is promising in the practical application of advanced oxidation technology in wastewater treatment.