Synthesis of 2D Intercalated Misfit Layered CoO Nanosheets from Quasi 1-D Ca Co O for Energy
Storage Applications

Transition metal oxides, renowned for their high energy storage capacity and redox activity, hold<br/>great promise in this regard. Among these oxides, intercalated cobalt oxide (CoO ) has emerged as a<br/>compelling candidate for electrochemical energy storage devices, but its metastable nature poses challenges<br/>for long-term stability. To address this, the intercalation of foreign atoms like calcium (Ca) has been<br/>investigated to stabilize the CoO crystal structure. This study presents a novel approach to synthesize twodimensional<br/>(2D) Ca intercalated CoO nanosheets from quasi-1D Ca Co O via a hydrothermal method. The<br/>investigation reveals that varying reaction times results in distinct crystal structures, yielding either intercalated<br/>CoO nanoscrolls or misfit layered nanosheets of CaCoO -CoO phase. These unique structures offer large<br/>surface areas, facilitating ion accessibility and efficient charge transport. The Ca intercalation process<br/>significantly enhances the stability of CoO .To the best of our knowledge, this work represents the first<br/>successful stabilization of 2D CoO with Ca intercalation, converting a quasi-1D structure into a misfit layered<br/>2D structure. Characterization techniques including SEM, TEM, high-resolution TEM, selected area electron<br/>diffractions, and EDS confirm the crystal structure and phase of the newly synthesised nanosheets.<br/>Furthermore, electrochemical evaluations as cathode materials for Zn-ion batteries demonstrate exceptional<br/>cycling stability and high specific capacity, establishing these nanosheets as promising candidates for future<br/>energy storage applications and beyond.