First-Principles Study on Magnetic MXenes for Free Radicals Trapping and Sensing

Abstract

Free radicals, characterized by unpaired electrons, exhibit high reactivity and are harmful to biological systems. However, conventional detection techniques, such as Electron Paramagnetic Resonance (EPR), suffer from limitations including large instrumentation size and restricted applicability. MXenes, leveraging their high specific surface area and tunable properties, present a highly promising alternative solution. In this work, we employ first-principles calculations to investigate the potential of magnetic MXenes as sensors for free radicals. We systematically examined the adsorption behavior of three representative free radicals (CH3·, OH·, and HO₂·) on sixteen distinct MXene substrates (M=Fe, Co, Ni, Mn; X=C; T=O, F, Cl, Br) by analyzing critical parameters like adsorption energy, changes in magnetic moment, and spin Hall conductivity. Our findings identify multiple MXene candidates with significant potential for practical application. Notably, Fe2CF2 and Fe2CBr2 exhibit outstanding performance for sensing CH3·, which is attributed to their remarkable variation in spin Hall conductivity, moderate adsorption energies, and pronounced changes in magnetic moment. This study not only elucidates the interaction mechanisms between MXenes and free radicals but also provides a theoretical foundation for designing novel, high-efficiency, and portable free radical sensors based on magnetic and electrical signal responses.