Ultrathin cobalt oxide nanostructures with morphology-dependent electrocatalytic oxygen evolution activity.

Engineering compositions, structures, and defects can endow nanomaterials with optimized catalytic properties. Here, we report that cobalt oxide (CoOx) ultrathin nanosheets (UTNS, ∼1.6 nm thick) with a large number of oxygen defects and mixed cobalt valences can be obtained through a facile one-step hydrothermal protocol.