Mesoporous Ni-rich Ni–Pt thin films: Electrodeposition, characterization and performance toward hydrogen evolution reaction in acidic media

Homogeneously mesoporous Ni–Pt thin films have been successfully synthesized by potentiostatic electrodeposition from an aqueous solution. The films are single-phase nanocrystalline Ni–Pt fcc solid solution and their composition can be adjusted with the deposition potential to a Ni content within 60-100 at%. The mesoporosity is constantly present, independent of the composition or microstructure, homogeneously distributed in all dimensions of the films with a pore diameter in the order of 10 nm. Film thickness is uniform and in the range of 200–300 nm. The films show improved performance over an electrodeposited Pt film at hydrogen evolution reaction (HER) and excellent stability in H2SO4 during 200 cycles. For the composition 84 at% Ni and 16 at% Pt, the overpotential required to reach a HER activity of −10 mA/cm2 is as low as −0.09 V vs. RHE. Meanwhile, the mesoporous alloy film with 95 at% Ni exhibits the highest activity with regard to the electrochemical surface area (ECSA).