Studies On The Hydrogen Electrode For Alkaline Water Electrolysis

Hydrogen energy has received considerable attention from all around the world, with its prominent merits, such as environmental protection, storable, renewable, and so on. Water electrolysis is an important way to get the vast and inexpensive hydrogen energy, but the cost of energy consumption increases, due to the hydrogen over potential to high voltage. To lower the potential of hydrogen and reduce the energy consumption, It is important to develop cheap and high catalytic activity of the hydrogen evolution materials. This thesis studied the preparation of the hydrogen evolution electrode material of high catalytic activity by electrodeposition, and studied the electrodeposition mechanism and electrochemical properties of hydrogen evolution reaction in 30wt% KOH solution, and characterized electrodes by SEM and EDS.The electrodeposition mechanism of Ni-Fe-W alloy was studied by the methods of electrochemistry, and the micromorphology and composition of Ni-Fe-W alloy were characterized. Cyclic voltammogram indicated that the electrodeposition of Ni-Fe-W alloy was irreversible growth process, and the electrocrystallization mechanism didn’t change with the variety of the concentration of WO42-. Chronoamperometric results indicated that the electrodeposition of Ni-Fe-W alloy at copper electrode belonged to a three-dimensional instantaneous nucleation mechanism. SEM images of electrodeposit showed that the Ni-Fe-W alloy was made of lots of crystalline grain which was several tens nanometers, and the atom composition was Ni58.76Fe32.72W8.52.Ni-Fe-W alloy electrode was prepared by electrodeposition. The influence of concentration of Na2WO4·2H2O, Na3Cit·2H2O and H3BO3, the electrodeposition current density, and the electrodeposition temperature on the catalytic activity of hydrogen evolution of the Ni-Fe-W alloy electrode were studied by the orthogonal and single factor experiment, and the optimal technics parameters for preparation of the electrode were made. SEM images of electrodeposit showed that the Ni-Fe-W alloy was made of lots of crystalline grain with rough electrode surface. The atom composition of Ni-Fe-W alloy electrode was Ni63.79Fe34.35W1.86 by EDS. The catalytic activity of Ni-Fe-W alloy for hydrogen evolution was higher than Ni-Fe electrode,Ni-W electrode,and Ni electrode. Under the same conditions, Ni-Fe-W alloy electrode over potentialη100 was 0.074V, which was about 0.377V lower than Ni electrode.The hull cell experimental results showed that the alloy consisted with Fe, Co, Ni and W four elements had good hydrogen evolution catalytic performance. By combining orthogonal test and single factor test, we studied the preparation of the Fe-Co-Ni-W alloy electrode and the optimal techniques parameters for preparation of the electrode were made. SEM images of electrodeposit showed that the Fe-Co-Ni-W alloy was made of lots of crystalline grain with rough electrode surface. The atom composition of Fe-Co-Ni-W alloy electrode was Fe67.27Co25.74Ni4.03W2.96 by EDS. Fe-Co-Ni-W alloy electrode over potentialη100 andη200 were 0.059V and 0.105V respectively. Its exchange current density(i0) was 2.61×10-2A?cm-2. And its apparent activation energy was 26.83kJ?mol-1. The Fe-Co-Ni-W alloy electrode had high hydrogen evolution catalytic performance.