Optical motion control of catalytic WS2 and MoS2 micromotors

Abstract

Herein we described the on-demand optically controlled braking and acceleration of transition metal dichalcogenide (TMD) based tubular catalytic micromotors. The direct electrodeposition of a thin WS2 or MoS2 outer layer imparts the micromotors with a direct bandgap for built-in optical responsive properties, along with light-induced heating. Thus, up to 70% speed acceleration is observed after irradiation from 365 to 535 nm. The phenomena can be explained by a mixed effect of electron generation and promotion from the active electronic levels of the outer WS2 or MoS2 micromotor layer, which recombines with the Pt layer, generating an additional peroxide input for increased speeds. The inherent photothermal properties of the TMD outer layer of the micromotors after light interaction also result in an increase in the temperature of the inner catalytic Pt layer, which results in increased decomposition kinetics. On-demand braking and acceleration of the micromotors can be thus achieved in the full electromagnetic spectrum, representing an alternative approach to control catalytic micromotor propulsion for a myriad of applications.