Hydrogen evolution at Ni foam electrodes and Ni-Sn coated Ni foam electrodes

The hydrogen evolution reaction (HER) was investigated in 1.0 M KOH at 25 °C at Ni foams with different pore sizes (450–1200 µm), and at the Ni-Sn/Ni foam electrodes, where Ni-Sn alloys were electrodeposited from the pyrophosphate-glycine bath using controlled potential coulometry (CPC) technique. The cross-section analysis revealed that rough Ni-Sn alloy covers complete available inner and outer foam surface, while investigated coating composition varied from 62 to 80 at% Ni (20–38 at% Sn). Comparing the HER polarization curves, the overpotential at j = −200 mA cm−2 was 427 mV lower for Ni-Sn samples than for bare Ni foams, while Tafel slopes changed from − 120 mV dec−1 at bare Ni foams to − 50 mV dec−1 for Ni-Sn/Ni foam samples. The lowest overpotential at − 100 mA cm−2 achieved is as low as − 77 mV. These cathodes could be promising 3D materials for industrial water electrolysis in zero-gap membrane flow cells.