Charge Transfer-Driven Conversion of Molecular Oxygen to Doublet State on Vanadium Diselenide (VSe2) Surface at Room Temperature

Abstract

Oxygen in the excited state is essential for organic synthesis and medical treatment. Herein, a novel phenomenon is reported in which the magnetic ground state of molecular oxygen undergoes a transition at room temperature from S = 1 to S = 1/2, corresponding to the transition of O₂ from a triplet to a doublet state after stable physical adsorption on the defect-free surface of bulk VSe₂. This density functional theory (DFT) calculations demonstrate the stable physical adsorption of O₂ on both 1T- and 2H-VSe₂ surfaces without further decomposition. Electron spin resonance (ESR) measurements confirm the spin state transition. Theoretical simulations reveal the charge transfer from entangled V-3d and Se-4p bands to oxygen as the leading cause of the spin state transition. This mechanism has not been previously proposed and offers multiple potential applications, from organic synthesis to medicine. Moreover, this approach can be extended to reveal new aspects of known catalytic materials and to design novel catalysts.