Electrocatalytic Activity of Electrodeposited Ni-P Micro-patterned Structure in Acidic Solution

摘要

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 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 H_2SO_4 solution, the current density at -0.75V vs saturated calomel electrode (SCE) was increased from 181 mA cm~(-2) to 426 mA cm~(-2), planar electrode to micro-structured electrode, which denoted a 2.35 times increase for 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. The computer simulation on the electric field distribution revealed that the effectiveness by raising the height of the microcolumns to increase the surface area had limitation. When the aspect ratio of the spacing channel between the columns became greater than 1, the electric flux was nearly unable to reach the bottom surface. Therefore, suitable configuration design in the micro-pattern is desired.