Rational design of molybdenum carbide loaded Fe3O4 for rapid and repeated water disinfection: Photothermal effect and bactericidal mechanisms

Access to safe and cost-effective water is essential for sustainable development. Microbial water pollution has become an issue of increasing global concern. However, conventional water disinfection methods are beset with numerous limitations and challenges, particularly the generation of harmful carcinogenic by-products associated with chlorine-based technologies. Hence, we reported α-MoC 1-x @CB-Fe 3 O 4 -6 (denoted as α-MCF-6) composite for effective water sterilization based on photothermal effect. The composite showed superior light absorption and photothermal property, enabling temperature elevation of α-MCF-6 dispersion (50 μg/mL) from ambient to 61.7 °C. The α-MCF-6 dispersion achieved 100 % inactivation of both E. coli and S. aureus after 10 min NIR irradiation (2 W/cm²), and more than 98 % sterilization efficiency over three reuse cycles. COMSOL Multiphysics® v. 6.3 simulations illustrated efficient photothermal heat transfer from irradiated nanomaterials to aqueous media, causing bulk heating. Gram staining confirmed close contact between bacteria and α-MCF-6, facilitating heat transfer from the material to bacteria. Additionally, EPR analysis verified the presence of hydroxyl radicals (•OH and O 2 •− ), which contributed to assisted effects. This work explored an application of molybdenum-based photothermal materials and provided a high performance and energy-saving water sterilization method. COMSOL Multiphysics® v. 6.3 simulations and Gram staining confirmed close contact and heat transfer from the material to bacteria.