On-the-fly catalytic degradation of organic pollutants using magneto-photoresponsive bacterialated microcleaners

Increasing accumulation of highly persistent and non-biodegradable organic pollutants in our fresh water sources imposes a threat to human health. Designing novel catalytic materials that can efficiently harness energy from their surroundings to degrade such problematic pollutants is essential. In this work, we fabricated core-shell microhelical robots composed of iron oxide@titanium dioxide (Fe₃O₄@TiO₂) for UV-visible light driven degradation of organic pollutants in a cost-effective manner. Biolating and sol-gel synthesis were employed for a simplified approach to batch-fabricate magnetic photocatalysts. These hybrid microrobots removed 97% of RhB dye from contaminated water in 75 minutes using UV-visible light (k-value of 0.047 min^-1). Furthermore, when photocatalytic degradation was performed under continuous magnetic field driven propulsion, 99% of RhB dye degraded in 40 minutes with a k-value of 0.108 min^-1. We also observed a strong correlation between the hybrid microhelices' swimming characteristics and their subsequent photocatalytic degradation efficiency. These results were further corroborated using COMSOL simulations.