MXene-induced electronic structure modulation of Fe-Al-LDH to boost the Fenton-like Reaction: Singlet oxygen evolution and electron-transfer mechanisms

Layered double hydroxide (LDH) based heterogonous peroxymonosulfate (PMS) activation degradation of pollutants has attracted extensive attention. The challenge is to selectively regulate the traditional free radical dominant degradation pathway into a nonradical degradation pathway. Herein, an interface architecture of Ti3C2Tx-MXene (MXene) loading on the Fe-Al LDH scaffold was developed, which showed excellent stability and robust resistance against harsh conditions. Significantly, the rate constant for tetracycline hydrochloride (TC) degradation in the MXene-LDH/PMS process was 0.421 min−1, which was ten times faster than the rate constant for pure Fe-Al LDH (0.042 min−1). Specifically, more reactive Fe with the closer d-band center to the Fermi level results in higher electron transfer efficiency. The occupations of Fe-3d orbitals in Mxene/Fe-Al LDH are pushed above the Fermi level to generate, which results in higher PMS adsorption and inhibition of the release of oxygen-containing active species intermediates, leading to the enhanced 1O2 generation. Additionally, the built-in electric field in the heterojunction was driven by the charge redistribution between MXene and Fe-Al LDH, resulting in a mediated-electron transfer mechanism, differentiating it from the Fe-Al LDH/PMS system. It was fascinating that MXene/Fe-Al LDH achieved satisfactory treatment efficiency in continuous column reactor and real landfill leachate.