Environmental Stimuli-Irresponsive Long-Term Radical Scavenging of 2D Transition Metal Dichalcogenides through Defect-Mediated Hydrogen Atom Transfer in Aqueous Media

Abstract

A transition metal dichalcogenide (TMD) based antioxidation platform is proposed, in which radical scavenging is accomplished by the defect-mediated one-step hydrogen atom transfer (HAT) occurring on the nanosheets in water. To this end, the TMD nanosheets, including MoS2, WS2, MoSe2, and WSe2, are finely dispersed in water with the aid of an amphiphilic poly(epsilon-caprolactone)-b-poly(ethylene oxide) (PCL-b-PEO) diblock copolymer that envelops the nanosheets with a molecular layer of less than 1 nm thickness. It is then demonstrated that the PCL-b-PEO-stabilized TMD nanosheets show the extraordinarily enhanced and prolonged radical scavenging activity in water even under harsh storage conditions. Theoretical modeling studies on HAT suggest that more favorable hydrogen association from chalcogen vacancies on the nanosheets dispersed in water can lead to the easier dissociation of hydrogen atoms with exothermicity by -0.43 to -1.33 eV, thus exhibiting such an outstanding radical scavenging performance.