Dual-propelled polydopamine@SiO2@Pt micromotor with asymmetrical yolk-mesoporous shell for the enhanced catalytic reduction

Micro/nanomotors exhibit unique self-propulsion capabilities at the micro/nanoscale, offering significant potential as nanocatalysts in the field of catalysis by enhancing the contact probability between catalytic active sites and reactant molecules. Herein, a dual-propelled polydopamine (PDA)@SiO₂@Pt micromotor with asymmetric yolk-mesoporous shell nanostructure is developed to enhance the catalytic reduction performance. The synthesis of PDA@SiO₂@Pt micromotor involves a two-step process. First, the mesoporous silica is grown on the surface of the thermally swelled PDA sphere through heterogeneous interface self-assembly. Subsequently, the Pt nanoparticles (Pt NPs) are selectively loaded onto the PDA yolk. The asymmetric PDA yolk demonstrates outstanding photothermal conversion abilities, generating local thermal gradients under near-infrared (NIR) light irradiation, which propels the micromotor through thermophoresis. Simultaneously, the Pt NPs on PDA yolk catalyze the decomposition of H₂O₂ decomposition, generating O₂ gradient that drives the micromotor through self-diffusiophoresis. The motion behavior of PDA@SiO₂@Pt micromotor can be controlled through adjusting the NIR light illumination power density or varying concentration of H₂O₂. Moreover, the mesostructured architecture of PDA@SiO₂@Pt micromotor can be employed to achieve the efficient catalytic reduction, achieving up to 93 % conversion of methylene blue (MB) within 5 min due to the combined effects of photothermal and particle motion properties induced by NIR light. The PDA@SiO₂@Pt micromotor exhibits immense potential for future applications in complex catalytic systems using multi-driven micro/nanomotors.