Autonomous self-propelled MnO₂ micromotors for hormones removal and degradation

Nowadays, endocrine-disrupting chemicals are recognized as among the most dangerous compounds for marine life and human health as well. Here, we present the use of commercially available MnO₂ microparticles as self-propelled micromotors for on-the-fly photocatalytic degradation and removal of the β-estradiol hormone due to the micromotors’ self-propulsion ability and photoactivity. Effective removal of the contaminant is demonstrated without any external stirring showing a degradation efficiency of 72%, significantly higher than static MnO₂ microparticles (27%). In particular, adsorption and photocatalytic processes were here exploited separately to evaluate the specific contribution of the motion toward the overall β-estradiol removal effect from the water. This study presents an effective alternative to conventional water purification in removing hormones and a starting point for future improvements on adsorption and photocatalytic abilities of micro- and nanomotors toward emerging organic pollutants in water.