Improved catalytic efficiency and stability by surface activation in Fe-based amorphous alloys for hydrogen evolution reaction in acidic electrolyte

• The self-supported amorphous FeMoPC with a sandwich structure was prepared by a two-step surface activation method. • The catalyst exposes abundant active sites attributed to a combination of the metastable state and nanoisland structures. • The catalyst exhibits an overpotential of 96 mV at 10 mA cm -2 with a Tafel slope of 51 mV dec -1 . • The catalyst exhibits excellent long-term stability due to the formation of acid resistant metal phosphate/oxide compact layer. The development of efficient and durable electrocatalysts for water splitting to produce hydrogen is of great significance to relieve the energy crisis. In this work, a self-supported FeMoPC amorphous catalyst with a sandwich structure prepared by the electrochemical activation-dealloying two-step method is reported. The catalyst exhibits a low overpotential of 96 mV at -10 mA cm −2 , a Tafel slope of 51 mV dec −1 , and excellent stability for over 16 h in 0.5 M H 2 SO 4 solution for hydrogen evolution reaction (HER). The good catalytic activity is attributed to the nanoislands with rich active sites and large reaction areas for efficient HER obtained by an electrochemical cyclic voltammetry scan activation. Additionally, the formation of a compact protective phosphate/oxide layer that has high concentration of Mo on the surface during the subsequent dealloying enhances the durability of the catalyst. This work overcomes the issues associated with poor durability of Fe-based catalyst in acidic electrolyte and broadens the application of Fe-based amorphous alloys.