Electron Donors in the Intertwined Interface Restore Oxy-Substituted Selenides

Nature chose selenium as the antioxidant element center in proteins, permitting the reversible conversion of organic bioenzymes between oxidized and selenized forms. Despite the importance of such antielectronegativity reversibility, it has not yet been demonstrated in inorganic selenides. We report an unexpected example showing that oxy-substituted sites in metal selenides can be restored to selenized forms reversibly by mild electrochemical manipulation in a copper aqueous solution. Synchrotron measurements of the localized lattice and bond structure suggest that copper as an electron donor can transfer extra electrons to oxidized metal centers via the O-V-Se-Cu-bonded bridge path in the deep-intertwined interface to confer rare reversibility. We demonstrate that such reversibility is generalized in vanadium diselenide and manganese diselenides/selenides, offering the possibility of applying promising selenides in widespread aqueous systems.