Metal-Free Visible-Light Photoactivated C₃N₄ Bubble-Propelled Tubular Micromotors with Inherent Fluorescence and On/Off Capabilities

Abstract

Photoactivated micromachines are at the forefront of the micro-and nanomotors field, as light is the main power source of many biological systems. Currently, this rapidly developing field is based on metal-containing segments, typically TiO 2 and precious metals. Herein, we present metal-free tubular micromotors solely based on graphitic carbon nitride, as highly scalable and low-cost micromachines that can be actuated by turning on/off the light source. These micromotors are able to move by a photocatalytic-induced bubble-propelled mechanism under visible light irradiation, without any metal-containing part or biochemical molecule on their structure. Furthermore, they exhibit interesting properties, such as a translucent tubular structure that allows the optical visualization of the O 2 bubble formation and migration inside the microtubes, as well as inherent fluorescence and adsorptive capability. Such properties were exploited for the removal of a heavy metal from contaminated water with the concomitant optical monitoring of its adsorption by fluorescence quenching. This multifunctional approach contributes to the development of metal-free bubble-propelled tubular micromotors actuated under visible light irradiation for environmental applications.

Carbon nitride-based light-driven microswimmers with intrinsic photocharging ability

“…Our findings reveal the light-induced surface catalytic processes and indicate that the reduction reaction, which is responsible for the microswimmer propulsion with alcohol donors in ambient conditions, is not the hydrogen evolution reaction (HER), but rather the oxygen reduction reaction (ORR), or more generally, the formation of reactive oxygen species (ROS), even when Pt or Au are used as cocatalysts. Under optimized conditions, our PHIbased Janus microswimmers move with comparable speeds of similar, melon type CN x -based microswimmers, and we demonstrate propulsion with visible light only (33,34).…”

Microrobots in Brewery: Dual Magnetic/Light‐Powered Hybrid Microrobots for Preventing Microbial Contamination in Beer

“…Autonomous self‐propelled devices that can navigate in complex liquid media and fulfill desired tasks have demonstrated potential advancements in diverse fields, for example, environmental remediation and biomedicine . In addition, these micro/nanorobots have been successfully used for cargo capture and transport of biological samples and organic molecules in fluids .…”

Multifunctional Visible‐Light Powered Micromotors Based on Semiconducting Sulfur‐ and Nitrogen‐Containing Donor–Acceptor Polymer

“…[ 14 ] To overcome these drawbacks, we recently described the fabrication of metal‐free graphitic carbon nitride‐based tubular micromotors that are capable to move under visible light irradiation and remove heavy metal pollutants from aqueous media. [ 15 ] To trigger their motion, however, it is necessary to add relatively high concentrations of toxic hydrogen peroxide as chemical fuel. [ 16 ] Therefore, it is still essential to investigate alternative routes toward the design and preparation of more efficient organic‐based fuel‐free micromachines that can be activated by visible light irradiation.…”