Molten metal-organic complex to synthesize versatile ultrathin non-layered oxides

Two-dimensional (2D) materials have attracted a great deal of research interest because of their unique electrical, magnetic, optical, mechanical, and catalytic properties for various applications. To date, however, it is still difficult to fabricate most functional oxides as 2D materials unless they have a layered structure. Herein, we report a one-step universal strategy for preparing versatile non-layered oxide nanosheets by directly annealing the mixture of metal nitrate and dimethyl imidazole (2-MI). The 2-MI plays the key role for 2D oxides since 2-MI owns a very low molten point and sublimation temperature, in which its molten liquid can coordinate with metal ions, forming a metal-organic framework, and easily puffing by its gas molecules. A total of 17 materials were prepared by this strategy, including non-layered metal oxide nanosheets as well as metal/metal oxide loaded nitrogen-doped carbon nanosheets. The as-prepared cobalt particle-loaded nitrogen-doped carbon nanosheets (Co@N/C) exhibit remarkable bifunctional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) electrocatalytic activity and durability. Besides, the Zn-air battery utilizing a Co@N/C catalyst exhibits high power density of 174.3 mW·cm−2. This facile strategy opens up a new way for large-scale synthesis of 2D oxides that holds great potential to push 2D oxides for practical applications.