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 electro-deposition 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/cm(2) 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).