COF nanotubes/2D nanosheets heterojunction for superior photocatalytic bactericidal activity even at low concentration and weak light

Abstract

Microbial fouling is a huge nuisance to equipment operation and human health. Two-dimensional (2D) photocatalytic materials such as g-C₃N₄, WSe₂, and Ti₃C₂T_x, show immense potential for solar-driven eradication of microbial fouling. However, limited photon absorption and rapid photogenerated electron-hole recombination curtail their photocatalytic efficiency and availability, resulting in the necessity to operate at high concentration and strong light. Herein, three kinds of covalent organic frameworks (COF) nanotubes/2D nanosheets heterojunctions (COF-x) were flexibly constructed by in-situ growing COF nanotubes on g-C₃N₄, WSe₂, and Ti₃C₂T_x nanosheet substrates via one-pot method. The internal electric field at the COF-x coupling interface enhanced the separation and migration of photogenerated charge pairs, contributing to the antimicrobial reactive oxygen species (ROS) produced by COF-x, which was 2.8–270 times more efficient than those of nanosheets. The bactericidal effect enhanced from 34.13 %∼41.68 % of pure nanosheets to over 99.86 % of COF-x at an ultra-low concentration of 2 µg/mL and a weak visible light of 15 mW/cm². At a low concentration of 20 µg/mL, the bactericidal rate of COF-x achieved nearly 100 % within 6 h. COF-x also showed exceptional environmental stability and antimicrobial properties under heat, light, acid, alkali, and aqueous conditions, offering a new perspective in photocatalytic antimicrobial/antifouling.