Highly efficient visible-light-driven Cu2O@CdSe micromotors adsorbent

Abstract Micro/nanomotors have attracted extensive attentions in aquatic environmental remediation, but the random motion and uncontrollability restricts the precise location and timely adjustment in micro-environmental remediation, such as in microchannels and microwells. Herein, we demonstrated visible-light-driven cadmium sulfide quantum dots doped cuprous oxide (Cu2O@CdSe) micromotors adsorbent with excellent removability to cationic dye, in along with effective motion regulation. The Cu2O@CdSe micromotors adsorbent with type II heterostructure was fabricated by simple in-situ deposition and exhibited outstanding motion controllability and instant response under visible light illumination. The existence of a staggered gap between Cu2O and CdSe formed a heterojunction, effectively inhibiting recombination of photogenerated electron-hole pairs and improving photocatalytic activity of Cu2O@CdSe micromotors. Negative phototactic self-propulsion with maximum speed to ∼42.3 μm/s was achieved in biological environments because of the formation of the asymmetric chemical concentration gradient around the motors. Additionally, by modulating the direction and on/off state of asymmetric light field, it is capable of steering motor moving with multiple controllable modes, such as horizontal, vertical, stop/go and patterned propulsion, which will facilitate the on-demand orientation once in the complex microchannel. Furthermore, the capability of Cu2O@CdSe micromotors adsorbent is confirmed with a rapid adsorption rate of 96% on methyl blue after 10 min. Additionally, the stability of micromotors is evaluated. Although with inevitable oxidation or photocorrosion for all Cu2O micromotor, the strong adsorption ability is promised with 5 times recycling in low concentration of dye solution. Such attractive micromachines with boosted motility and lower production cost hold a considerable promise for a complex environmental remediation.