Hierarchical hollow nanocages derived from polymer/cobalt complexes for electrochemical overall water splitting

Because of the energy crisis and environmental problems, the preparation of highly active, stable, and low-cost electrocatalysts for hydrogen evolution (HER) and oxygen evolution (OER) has great meaning to the sustainable development. In this work, we design a novel hierarchical hollow nanocomposite that is made up of CoP hollow nanoparticles (NPs) and hollow N-doped carbon nanocages (CoP@NCHNCs) derived from polydopamine (PDA)/cobalt nanocontainers (PDA/Co HNCs) through a pyrolysis- phosphidation method. PDA was chosen as the carbon precursor and offered both the oxygen atom for the phosphidation process and pyrrolic N to facilitate the electrocatalyst activity. Benefiting from the unique hierarchical hollow structure and pyrrolic N derived from PDA, the CoPg NCHNCs exhibit outstanding performance for overall water splitting. For OER and HER, only a low overpotential of 304 and 93 mV at 10 mA-cm(-2) is needed, respectively. Furthermore, CoP@NCHNCs can be used as anodes and cathodes to achieve 10 m.Acm(-2) at 1.62 V. This work demonstrates the potential of hierarchical hollow materials for electrocatalytic overall water splitting and opens a new way to construct highly active electrocatalysts by using polymers as a precursor.