Sodium percarbonate fuel-driven magnetic micromotor for rapid detection and efficient removal of tetracycline: Synergistic effect of oxygen vacancy and dissolved oxygen.

Micro/nanomotors (MNMs) propelled by hydrogen peroxide (HO) fuel have garnered significant interest in sensitive colorimetric detection and rapid catalytic degradation of organic pollutants. However, their practical applications remain constrained by multiple limitations including toxic high-concentration HO requirements, sluggish Fe/Fe redox cycling, and secondary contamination risks from metal ion leaching. Herein, we rationally developed a novel magnetic tubular FeCu@NC/MnO micromotor through multistep fabrication using kapok-derived C microtubes as templates. The micromotor demonstrated remarkable propulsion (126.47 μm s) under 0.5 M sodium percarbonate (SPC) solution and magnetic guidance, achieving eco-friendly fuel utilization by replacing unstable liquid HO with solid SPC. Benefiting from abundant active sites and oxygen vacancy (O), the micromotor exhibited dual functionality in SPC activation with both sensitive colorimetric detection (LOD = 0.214 μM) and efficient catalytic degradation of tetracycline (TC, 93.73 % removal within 90 min). Quenching experiments and electron paramagnetic resonance (EPR) revealed a free radical and non-radical pathway involving hydroxyl radicals (•OH) and singlet oxygen (O) in TC degradation. More importantly, the O-mediated electron transfer facilitated Cu/Cu, Fe/Fe, and Mn/Mn redox cycling, while synergistic O and dissolved oxygen (DO) interactions promoted the generation and conversion of reactive oxygen species (ROS, •OH → O → O). This study provides fundamental insights into O- and DO- mediated ROS generation/transformation mechanisms and offers a paradigm for designing defect-engineered micromotor in environmental remediation.