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.