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

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 Bi84.8Ni15.2 alloy as the cathode to establish a full-cell (IrO2∥Bi84.8Ni15.2) 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).