Hybrid magneto-photocatalytic microrobots for sunscreens pollutants decontamination

Growing awareness of the harmful effects derived from sunlight overexposure has led to a regular use of sunscreens. Nonetheless, major environmental side-effects have been concurrently originated due to the increasing concentration of related pollutants. Considering the advantages that microrobots offer for water remediation tasks, magnetically-driven photoactive microrobots (i.e., MG-µROSES) are here developed as a pioneering response from the field to face this global threat. Particularly, photoactive bismuth oxyiodide (i.e., BiOI) flower-like microparticles (i.e., µROSES) have been prepared and modified with tailored Fe3O4 nanoparticles through a mild surface functionalization. Therefore, static µROSES acquired an appealing magnetic steering motion and an easy retrieval without sacrificing large BiOI surface areas. The performance of MG-µROSES against the main organic UV-filter in suntan lotions (i.e., oxybenzone, BP-3) has been analyzed. An effective photocatalytic degradation —in pure water and under visible light— has been observed and attributed to the synergistic combination of adsorption and photocatalytic activity provided by this appropriate design. Moreover, the noticeable enhancement of the photocatalytic degradation of BP-3 by MG-µROSES has been linked to their magnetically-driven navigation, favoring an on-the-fly: (i) adsorption of BP-3; and (ii) distribution of the photogenerated reactive oxygen species, in particular hydroxyl radicals (OH·)). All in all, an efficient strategy based on photoresponsive magnetic microrobots against sunscreens residues is presented. Hence, a potential contender to beat alternative traditional methodologies is offered.