MXene-mediated electron transfer in Cu(II)/PMS process: From Cu(III) to Cu(I)

There exists an obvious contradiction between Cu(III) generation and Cu(I) contribution in reductants enhanced Cu(II)/peroxymonosulfate (PMS) process because the involved electron transfer pathways were always ignored in previous studies. This study investigated the MXene-mediated electron transfer mechanism in Cu(II)/PMS for the first time. The introduction of MXene significantly promoted atrazine degradation under acidic condition because the in-situ generation of Cu(I) was an excellent activator for PMS. Under alkaline condition, although addition of MXene generated a large amount of Cu(I), the degradation of atrazine was inhibited due to that the conversion of Cu(I) to Cu(III) was interrupted. The strong metal-support interaction (SMSI) altered the reactive intermediate species from Cu(III) (two-electron transfer) to hydroxyl radical (HO•) and sulfate radical (SO4•-) (one-electron transfer) under alkaline condition. This work proposed a novel MXene-mediated electron transfer mechanism and improved the understanding of Cu(III)/Cu(I) transformation pathway.