Covalent Organic Framework Derived Mo2C-MoNi4 Chainmail Catalysts for Hydrogen Evolution

•Mo2C-MoNi4-based chainmail catalyst as stable HER catalysis was prepared.•N-rich COF was used as a sacrificial template to form N-doped graphene shells.•Charge transfer from Mo to N-doped graphitic layer optimized the Mo–H bond.•Graphene layers protect active MoNi4 cores from electrolyte erosion.•The optimized catalyst presents favorable HER activity and excellent stability.