Insight into the piezo-activation of peroxymonosulfate by 1T/2H-MoS2: piezopotential boosting the formation of Mo-peroxymonosulfate complexes as the major reactive species

Piezocatalysis coupled with peroxymonosulfate (PMS)-based advanced oxidation processes (AOPs) is of current interest due to its great promise in water decontamination. MoS 2 nanoflowers (NFs) with intriguing piezoelectric properties have been widely utilized for piezo-activation of PMS, while the underlying mechanism is still controversial. Here, we conduct a thorough investigation on the mechanism involved in piezoelectric PMS activation over a multiphasic MoS 2 NFs (1T/2H-MoS 2 ) piezocatalyst. The findings demonstrate that the intrinsic active sites in 1T/2H-MoS 2 played an important role during the PMS piezo-activation process and the piezopotential mainly promoted the complexation between PMS and active sites, instead of driving the piezo-induced charges to activate PMS. Specifically, the piezo-activated 1T/2H-MoS 2 /PMS system manifests different organic substrate-dependent reactivity from the radical-based and 1 O 2 -based AOPs systems, though suppressive effects on the pollutant degradation were witnessed during the regular radical quenching tests. Further comprehensive experimental results and in situ Raman analysis suggested that surface-bounded Mo-PMS complexes instead of previously proposed free radicals and 1 O 2 are the main reactive species in the piezo-activated system. With the aid of computational modeling, the bond configurations of Mo-PMS complexes were elucidated and the thermodynamic feasibility of oxygen atom-transfer reactions between the complexes and pollutant was proved. Finally, a piezoelectric reaction column filled with 1T/2H-MoS 2 /hydrogels composites was demonstrated to be efficient for continuously removing carbamazepine in lake water due to the specific selectivity of surface-bounded Mo-PMS complexes. Our results shed new perspectives for the mechanistic understanding of piezocatalysis coupled with PMS-AOPs for water remediation. • Piezopotential enhanced the complexation between peroxymonosulfate (PMS) and MoS 2 . • The Mo(IV) active sites played a key role during the PMS piezo-activation process. • Mo-PMS complexes are the main reactive species in the piezo-activated system. • Free-standing 1T/2H-MoS 2 /hydrogels composites piezocatalysts were fabricated. • A new perspective for mechanistic understanding of piezocatalysis-coupled PMS-AOPs.