Synthesis of Sub-1 Nm 2d Transitional Metal Oxides Via Anion Exchange-Bonds Cleavage Cascade Reactions

Two-dimensional (2D) transition metal oxides (TMOs) are widely applied in various research fields. A reliable, general, and facile synthetic protocol applicable for a large variety of 2D TMOs is in emergent demand. S-S/Se-Se bonds widely exist in various metal sulfide/selenide layered crystals. We demonstrated that 2D TMOs could be fabricated from metal sulfide/selenide with S-S bonds or Se-Se bonds by a novel H2O2-mediated anion exchange-bonds cleavage cascade reactions strategy. Specifically, the addition of H2O2 induced the anion exchange in these crystals from S-S/Se-Se to O-O. The O-O bond is fragile than S-S or Se-Se bond, proving by the density functional theory (DFT) calculations. Then, the O-O bonds in the layered crystals were cleavaged to form the sub-1 nm 2D TMOs. 2D CuO2, CuO, and Mn3O4 were fabricated by this method successfully. As an exaple of appilication, we used the ultrathin 2D CuO2 as a biomaterial for cancer treatment. 2D CuO2 have easier biodegradability, more robust reactivity, and higher drug loading efficiency than CuO2 nanoparticles