Synergy of Single-Atom Catalysts and Support Promoted Peroxymonosulfate Activation for Efficient Water Purification: The Overlooked Hydrogen Bond Role

Metal active sites, especially single-atom catalysts (SACs), have garnered significant interest in Fenton-like processes for the degradation of refractory organic pollutants in water. However, the contribution of the hydrogen bond on the catalyst support to the catalytic performance is always overlooked. Herein, a typical cobalt SAC anchored on Mo2TiC2Tx MXene (denoted as Co-SA@Mo2TiC2Tx) was synthesized and used as the model catalyst to investigate the interaction of catalyst and surface hydrogen bond for peroxonosulfate (PMS) activation. The synthesized Co-SA@Mo2TiC2Tx catalyst with a Co–O3 coordination structure and abundant hydrogen bond network had potent oxidation ability toward 4-chlorophenol with a rapid reaction rate and superior durability. Importantly, this catalyst exhibited exceptional performances across various refractory organic compounds and different water matrix. Physical experiments, theoretical calculations, and in situ spectroscopy investigations showed that the formed surface hydrogen bond between PMS and support could regulate the adsorption configuration of PMS and further facilitate its activation via rapid electron transfer; simultaneously, the formation of singlet oxygen (1O2) was thermodynamically favorable and invoked as the main reactive oxygen species responsible for the oxidation performance. This work offers new perspectives on the role of the hydrogen bond in enhancing metal sites for efficient PMS activation.