Hybrid-Fueled OV-CuFe-CNT/MnO₂/GOx Micromotor for Colorimetric Detection and Degradation of Captopril via Free Radical and Nonradical Mediated by Oxygen Vacancy

Addressing the challenges of metal particle corrosion and active site loss induced by excessive use of high-concentration hydrogen peroxide (H₂O₂) is essential to expand micro/nanomotor (MNM) applications in biological and environmental fields. Herein, a novel hybrid fuel-driven CuFe-CNT/MnO₂/GOx (GOx, glucose oxidase) micromotor with abundant oxygen vacancy (OV) was successfully constructed for synchronous high-efficiency colorimetric detection and rapid degradation of captopril (CP). Using glucose and low-concentration H₂O₂ as hybrid fuels, the OV-CuFe-CNT/MnO₂/GOx micromotor could move at a speed of 107.45 μm s^-1. The OV-rich architecture facilitated electron-rich surface states that enhanced H₂O₂, dissolved oxygen (DO) and O₂ adsorption, and cleavage to generate hydroxyl radicals (^•OH), while mediating superoxide radical (O₂^•-) formation through oxygen reduction cascades, further evolving into singlet oxygen (¹O₂). Based on the coupling of self-reinforcing diffusion effect of micromotor and free radical and nonradical mediated by OV, a platform was developed for the sensitive colorimetric detection and rapid removal of CP. The detection limit of CP on this platform was below 0.1625 μM, and the removal efficiency of CP within 120 min reached as high as 96.54%. Additionally, the density functional theory (DFT) calculations predicted possible reaction sites in the molecular structure of CP, which also confirmed that CP degradation was a free-radical and nonradical process dominated by ^•OH and ¹O₂. This micromotor-based wastewater treatment strategy, leveraging both free-radical and nonradical pathways, will offer new insights for the subsequent rational design and application of "defective" MNMs.