Shape-controlled Mn–Fe PBA derived micromotors for organic pollutant removal

Abstract

A new simple strategy to prepare Mn–Fe Prussian blue analogue (PBA) derived oxide micromotors through co-precipitation and heat treatment is demonstrated. The morphology of the precursors could be precisely controlled from cubic-like to spherical-like by introducing citrate. Because of the synergistic catalytic reaction of bimetallic Mn–Fe oxides, micromotors with different shapes could be powered efficiently in H₂O₂ solution. In particular, the obtained cubic Mn–Fe oxide micromotors showed strong propulsion at a speed of 71.21 μm s⁻¹ in 1% H₂O₂ solution. With dual mechanisms of adsorption bubble separation (ABS) and Fenton oxidation, the cubic Mn–Fe oxide micromotors showed extraordinary removal ability for Rhodamine B (RhB) as a simulated pollutant and could remove up to 95.2% of RhB within 30 minutes. Magnetic Fe₃O₄ contained in the component not only could degrade organic pollutants, but also could be recycled by magnetic field and reused with high degradation efficiency. These dual-functional metal oxide catalytic micromotors provide a practical and environmentally friendly strategy for environmental restoration.