Visible light driven MoS2/α-NiMoO4 ultra-thin nanoneedle composite for efficient Staphylococcus aureus inactivation

Abstract

MoS2/α-NiMoO4 ultra-thin nanoneedle composite was synthesized by microwave hydrothermal process in one step. The nanocomposite revealed the complete destruction of multidrug resistant Staphylococcus aureus (S. aureus) within 150 min under visible light irradiation. According to electron spin resonance measurement and radical trapping experiment, it has been established that O2¯ acts as a major active species for bacterial inactivation in visible light. The bacterial inactivation was further proved by membrane deformities in bacterial cell membrane, DNA fragmentation, and protein destruction. TEM- elemental mapping confirms the inactivation of S. aureus by reactive oxygen species (ROS) but not the toxicity of photocatalyst. Transient photocurrent responses, electrochemical impedance spectroscopy, and cyclic voltammetry measurements reveal the efficient separation of electron-hole pairs in the composite photocatalyst. The composite photocatalyst shows greater ROS production, higher degree of DNA fragmentation and protein degradation, detrimental effects on the morphology of the bacterial cell wall, outstanding transient photocurrent responses, reduction of interfacial charge transfer resistance, superb oxidation/reduction potential, strong visible light absorption, and adequate separation of photogenerated electron-hole pairs as compared to host photocatalyst. The photocatalytic inactivation mechanism was explained. So, this promising composite photocatalyst can be applied for inactivation of multidrug resistant bacteria in biological waste water.