Flattening sol–gel nanospheres into a carbon sheet-intercalated cobalt/carbon/cobalt sandwich-nanostructure †
It is known that carbon layer intercalation can reduce and even avoid the breakdown of matrix material induced by expansion in hydrogen storage processes. Herein, we provide a general strategy to synthesize a uniform cobalt/carbon/cobalt sandwich-like nanosheet stack (denoted as Co/C/Co), which is difficult to achieve using conventional one-pot synthetic methods. In this strategy, sol–gel nanospheres covered with cobaltII–cobaltIII layered double hydroxide (CoII–CoIII–LDH) were firstly constructed and used as a precursor. After a simple post-treatment the sandwich-nanostructures were successfully obtained, which display an extra high capacity, excellent high-rate capability, and long cycle life. Distinct from the most common structures of carbon-based composites (mixed, wrapped, or anchored models), the resultant materials display a uniform sandwich-like configuration: few-layer carbon sheets conformably intercalate cobalt nanoparticles. This facile strategy can be easily extended to design other metal/carbon/metal sandwich-like nanomaterials.