Ti3C2 quantum dots/hydroxypropyl methylcellulose modified Bi2WO6 for enhancing piezo-photocatalytic degradation of tetracycline

Abstract

A ternary composite of Ti₃C₂ quantum dots, hydroxypropyl methylcellulose, and Bi₂WO₆ effectively harnesses both optical and mechanical energy to achieve a strong piezo-phototronic effect for the removal of tetracycline hydrochloride. Under external mechanical stress, this system maintains a tightly integrated heterostructure, dynamically facilitating charge transfer across the nanosheets. Notably, the catalytic activity of the Ti₃C₂ quantum dots/hydroxypropyl methylcellulose/Bi₂WO₆ composite has been significantly enhanced, exhibiting a kinetic rate constant of 0.146 min⁻¹, which is 9.7 and 7.3 times higher than that of Bi₂WO₆ under pure photocatalytic and piezocatalytic conditions, respectively. The enhanced piezo-photocatalytic performance can be attributed to several synergistic factors: (i) Charge carriers move in the direction of external forces while holes move in the opposite direction, reducing the recombination efficiency of photoexcited electrons and holes; (ii) The good dispersibility and abundant hydroxyl groups of hydroxypropyl methylcellulose enable the even distribution of Ti₃C₂ quantum dots. Moreover, they form strong hydrogen bonds between Ti₃C₂ quantum dots and Bi₂WO₆, significantly promoting charge transfer and system stability; (iii) Ti₃C₂ quantum dots serve as electrons accepter of photogenerated carriers on the surface of Bi₂WO₆ nanoplates, accelerating the separation and migration of photoelectrons. This work demonstrates the successful construction of a stable organic–inorganic ternary catalytic system and elucidates its underlying mechanism, offering a promising strategy to boost the piezo-phototronic effect in advanced wastewater treatment applications.