Silver-enhanced Photoresponsive g-C₃N₄/Ag Janus Microrobots With Negative Photogravitaxis Efficient Antibiotic...

Water pollution remains a serious global challenge; hence, the efficient, low-cost, and environmentally friendly removal of pollutants from water has become a research hotspot. Photocatalytic microrobots can achieve autonomous movement and generate reactive oxygen species (ROS), presenting a great opportunity for water purification. Despite the excellent properties of g-C₃N₄, such as high photocatalytic activity, high surface area, tunable bandgap, and low cost, only a few studies have focused on g-C₃N₄-based microrobots. Herein, we developed g-C₃N₄/Ag Janus microrobots that display negative photogravitaxis and efficient photocatalytic activity. Silver modification promotes the generation and separation of charge carriers while suppressing their recombination, enabling the microrobots to move upward. This three-dimensional movement enhances mass transfer between pollutants and microrobots. We utilized the microrobots to degrade tetracycline with an efficiency of 88%, which is attributed to ROS generation and light-driven propulsion. This work not only demonstrates negative photogravitaxis in g-C₃N₄/Ag-based microrobots but also reveals their motion-enhanced photocatalytic mechanism for antibiotic degradation. These findings are expected to significantly advance the development of microrobotic systems for water purification and broader environmental remediation applications.