Polyaniline Derived N‐Doped Carbon‐Coated Cobalt Phosphide Nanoparticles Deposited on N‐Doped Graphene as an Efficient Electrocatalyst for Hydrogen Evolution Reaction

The development of highly efficient and durable non‐noble metal electrocatalysts for the hydrogen evolution reaction (HER) is significant for clean and renewable energy research. This work reports the synthesis of N‐doped graphene nanosheets supported N‐doped carbon coated cobalt phosphide (CoP) nanoparticles via a pyrolysis and a subsequent phosphating process by using polyaniline. The obtained electrocatalyst exhibits excellent electrochemical activity for HER with a small overpotential of −135 mV at 10 mA cm−2 and a low Tafel slope of 59.3 mV dec−1 in 0.5 m H2SO4. Additionally, the encapsulation of N‐doped carbon shell prevents CoP nanoparticles from corrosion, exhibiting good stability after 14 h operation. Moreover, the as‐prepared electrocatalyst also shows outstanding activity and stability in basic and neutral electrolytes. An N‐doped graphene supported N‐doped carbon coated cobalt phosphide nanoparticles (CoP@NC) core–shell structure is fabricated by using polyaniline, which is used both as N source for N doping and carbon cover. Due to the synergistic effect of the NC shell, CoP, and N‐doped graphene, the composite shows high hydrogen evolution reaction activity and good stability in acidic, neutral, and basic electrolyte.