Photocatalytic Pt/Ag₃VO₄ micromotors with inherent sensing capabilities for corroding environments

Autonomous self-propelled micromachines based on semiconductors are at the forefront of environmental pollutants degradation research to palliate the effects of the contamination arising from the constant manufacturing of new products. Nonetheless, testing these micromotors with real-life products is almost an unexplored field, limiting the degradation of pollutants to single-component aqueous solutions or suspensions at the laboratory scale, which hinders the translation of these micromachines into useful systems. Herein, Ag₃VO₄ has been devised as a micromotor by an asymmetric deposition of a thin layer of Pt, giving rise to Pt/Ag₃VO₄ micromotors (Janus particle). Their motion capabilities have been demonstrated under UV light in fuel-free conditions. Their photocatalytic performance at laboratory scale has been confirmed for the degradation of Rhodamine B while, as a first approximation of a real-life application, the degradation of an energy drink has also been tested. During this latter exploration, the Pt/Ag₃VO₄ micromotors were corroded by the citric acid present in the pollutant, releasing Ag nanoparticles into the media. As a proof of concept, the position of the generated Ag nanoparticles’ surface plasmon resonance absorption maximum has been demonstrated to show a dependency on the concentration of citric acid.