One-Step Radical-Intensified Selective Etching (RISE) Strategy for High-Yield Synthesis of Monolayer MXene with...

MXenes have gathered immense scientific attention due to their unique combination of high electronic conductivity, hydrophilicity, and reduced dimensionality. While considerable advances in synthetic methodologies, achieving rapid, high-yield production of dispersible monolayer MXenes with controllable in-plane structure remains a daunting challenge. Herein, we report an ultrafast radical-intensified selective etching (RISE) tactic that enables one-step mild synthesis of monolayer Ti₃C₂T_x MXene bearing customized in-plane nanoholes with near-quantitative etching efficiency (∼99.9%) within merely 3 h. By fine-tuning the dosage of H₂O₂, which generates hydroxyl radicals (·OH) in situ, defect-lean monolayer MXene was made in a high yield of 81.6%. Liters of such colloidal dispersion of monolayer MXene were obtained within hours, which could be readily processed into conductive films with improved oxidation resistance. Mechanistic studies reveal that the RISE protocol follows a radical-driven redox pathway fundamentally distinct from traditional proton-mediated etching routes. As a proof of concept, holey MXene-derived conductive films demonstrated an exceptional desalination capacity of 32.71 mg g^-1 in capacitive deionization, outperforming most pure MXene-based electrode materials. Our method can potentially revolutionize the prevailing wet chemical etching protocol used for a decade for yielding monolayer MXene and establishes a swift pathway toward customizable MXene architectures for energy and environmental applications.