2D-Material-Integrated Micromachines: Competing Propulsion Strategy and Enhanced Bacterial Disinfection.

ABSTRACT

2D transition-metal-dichalcogenide materials, such as molybdenum disulfide (MoS2 ) have received immense interest owing to their remarkable structure-endowed electronic, catalytic, and mechanical properties for applications in optoelectronics, energy storage, and wearable devices. However, 2D materials have been rarely explored in the field of micro/nanomachines, motors, and robots. Here, MoS2  with anatase TiO2  is successfully integrated into an original one-side-open hollow micromachine, which demonstrates increased light absorption of TiO2 -based micromachines to the visible region and the first observed motion acceleration in response to ionic media. Both experimentation and theoretical analysis suggest the unique type-II bandgap alignment of MoS2 /TiO2  heterojunction that accounts for the observed unique locomotion owing to a competing propulsion mechanism. Furthermore, by leveraging the chemical properties of MoS2 /TiO2 , the micromachines achieve sunlight-powered water disinfection with 99.999% Escherichia coli lysed in an hour. This research suggests abundant opportunities offered by 2D materials in the creation of a new class of micro/nanomachines and robots.