| dc.description.abstract | In this study, Ni-Mo-W ternary alloy micro columns were prepared by Micro-anode guided electroplating (MAGE), and their electrochemical properties for hydrogen evolution in 1 M KOH were investigated. The advantage of micro columns is that a three-dimensional electrode can be produced in a very small area to replace the thin-film electrode, which increases the active surface area of the hydrogen evolution catalytic electrode. Hydrogen-producing ternary alloy micro columns. This MAGE electroplating system uses a platinum wire covering a glass tube with a diameter of 127 μm as the anode, and a copper wire with a diameter of 0.643 mm as the cathode. The voltage between the two electrodes (6.5, 6.0, 5.5, 5.0 V) and the gap(20, 40, 60, 80, 100 μm) were used as deposition parameters. The electrolyte formula is made of 0.38 M ammonium chloride, 0.36 M sodium pyrophosphate, 0.15 M nickel sulfate hexahydrate, 0.064 M sodium molybdate dihydrate, 0.04 M sodium tungstate dihydrate and water. The surface morphology of the obtained micro columns was observed by SEM, the chemical composition was analyzed by EDS, the crystal structure was determined by XRD, and the COMSOL electric field was simulated. Afterwards, the alloy micro columns were immersed in 1.0 M KOH to conduct electrochemical tests such as cyclic voltammetry and Tafel polarization curve to observe the electrochemical properties and hydrogen evolution efficiency of the nickel-molybdenum-tungsten alloy. The results show that at a deposition voltage of 6.5 V, the gap of 60 μm, the nickel content is 25.4 at.%, the molybdenum content is 64.7 at.%, and the tungsten content is 9.9 at.%. It has the best hydrogen production efficiency in 1.0 M KOH. The Tafel slope is only 64.8 mV/dec. The lower the Tafel slope, the higher the reaction rate can be obtained with a smaller overpotential. When the current density is at -10 mA/cm2, the overpotential is only 43 mV, and the onset potential of the hydrogen production reaction is -0.123 V v.s RHE. The lower the two are, the less energy is consumed for hydrogen production, and platinum still has better hydrogen production efficiency. Its overpotential (η10) and the onset potentials are only 30 mV and -0.04 V v.s RHE, respectively. However, the price of platinum is very expensive (33243 USD/kg). In comparison, the cost of nickel-based alloys in this experiment (35 USD/kg) is only one thousandth of platinum. Therefore, the cost of hydrogen production can be effectively reduced. | en_US |