The HER property of electrodeposited Ni-P electrode with micro-patterned structure

Ni-P alloy has been shown to be a potential electrode material for hydrogen production from electrolysis. The enhancement of its electrocatalytic efficiency with micro-patterned structures fabricated using microelectromechanical system (MEMS) process was investigated in this study. The cylindrical columns with diameter of 65μm and spacing of 105μm were fabricated in rectangular array and two different heights. From the potentiodynamic polarization curves measured in 0.5M H₂SO₄ solution, the current density at -0.75V_SCE was increased from 181mA cm^-2 to 426 mA cm^-2, planar electrode to micro-structured electrode, which denoted a 2.35 times increase for hydrogen evolution reaction (HER) efficiency. It was noted that enhancement in HER efficiency was higher than the corresponding increment in apparent surface area. The electric field concentration at the edges of the columnar structure could contribute to the raise in efficiency. However, as the overplating occurred, the narrowing of the spacing between the top portions of the microcolumns could impede the electric flux into their bottom parts. Part of the surface area became less active in HER. Therefore, suitable configuration design in the micro-pattern is desired.