CoP/N-Doped Carbon Hollow Spheres Anchored on Electrospinning Core–Shell N‑Doped Carbon Nanofibers as Efficient Electrocatalysts for Water Splitting

In this work, a series of hybrids of CoP/N-doped carbon hollow spheres anchored on core–shell N-doped carbon nanofibers were facilely fabricated by the electrospinning technique followed by pyrolysis and phosphorization. The as-prepared hybrids exhibited greatly enhanced bifunctional electrocatalytic activities for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) compared to either moiety of CoP/N-doped carbon hollow spheres and core–shell N-doped carbon nanofibers. Especially, the optimum CoP/NCF-200 hybrid exhibited high performances and stabilities for OER in alkaline conditions and for HER in both acidic and alkaline electrolytes. The catalyst also exhibited excellent performance for overall water splitting as both anodic and cathodic catalysts in alkaline media. The density functional theory calculations suggest that the synergy between CoP and N dopants leads to higher catalytic activities for HER and OER and the C atoms between N atoms in the carbon layer are the catalytically active sites for the HER.