Bismuth–nickel bimetal nanosheets with a porous structure for efficient hydrogen production in neutral and alkaline media

Abstract

Active and durable electrocatalysts are very important for efficient and economically sustainable hydrogen generation via electrocatalytic water splitting. A bismuth–nickel (Bi–Ni) bimetal nanosheet with a mesoporous structure was prepared via a self-template electrochemical in situ process. The Bi–Ni catalyst required overpotentials of 56 mV and 183 mV at 10 mA cm⁻² for the hydrogen evolution reaction (HER), which were close to that of commercial Pt/C in 1.0 M KOH and 1.0 M PBS (pH 7.0), respectively. The electrocatalyst maintained a steady current density during 20 h electrolysis in 1.0 M KOH and 1.0 M PBS (pH 7.0). Density functional theory (DFT) indicated that the alloying effect could induce charge transfer from the Bi atom to Ni atom and thus modulate the d-band centre of Bi–Ni nanosheets, which could efficiently accelerate H* conversion and H₂ desorption at the Ni active site. This promotes the HER kinetics. By adopting the Bi_84.8Ni_15.2 alloy as the cathode to establish a full-cell (IrO₂∥Bi_84.8Ni_15.2) for water splitting in 1.0 M KOH, the required cell voltage was 1.53 V to drive 10 mA cm⁻², which was lower than that of the IrO₂∥Pt/C electrolyzer (1.64 V@10 mA cm⁻²).