Preparation And Catalytic Activity Of Electrode Materials For Water Electrolysis

Hydrogen production has received much attention recently with its potential application as an efficient, undefiled and ideal secondary energy sources. Water electrolysis is one of the most important ways to mass-produce hydrogen. However, industrial water electrolysis is not currently cost-competitive mainly owing to the high energy consume. Therefore, it is significant to research and develop a kind of electrode material with high electrocatalytic activity. In the present work, the electrode materials for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) were prepared by electrodeposition and thermal decomposition, respectively. The electrocatalytic activity for the HER and OER were evaluated using electrochemical analytic methods.Ni-Fe-TiO₂ composite electrode was firstly prepared by electrodeposition. Using single-factor experimentation, the effects of technological parameters, such as particle concentration, current density, temperature and time on the electroactivity of the coating have been studied. The appearance of the composite coatings has been analyzed by the SEM, EDS and XRD methods. The apparent and intrinsic activity of the coatings for hydrogen evolution (HER) were studied in 3mol L-1 NaOH solution using steady-state polarization and electrochemical impedance spectroscopy (EIS) methods. Also, the electrocatalytic activity of Ni-Fe-TiO₂ electrode was prepared with pure Ni electrode, Ni-Fe alloy electrode, Fe-TiO₂ composite electrode and Ni-TiO₂ composite electrode.The results demonstrated the highest electrocatalytic activity of the Ni-Fe-TiO₂ coatings for HER in comparison with the Ni, Ni-Fe, Fe-TiO₂ and Ni-TiO₂ coatings, by reason of its higher apparent exchange current density, i0, and lower overpotential,ηH 2, when the condition of reaction was the same. Moreover, the value of the activation energy of Ni-Fe-TiO₂ composite coating was smaller than any other electrodes which prepared in our experiment, implying that the HER reaction was more easily taken place on the Ni-Fe-TiO₂ composite coating than others. Besides, faradaic resistance for the charge transfer process, Rct, was lower than the ones of other four electrodes, and the roughness factor of Ni-Fe-TiO₂ coating was the largest. In a word, the highest electroactivity of the Ni-Fe-TiO₂ composite coating was proved by two factors: the factor of geometry, and the activation energy.Nickel foam/Ni-Co-O compound oxide film electrode material for oxygen evolution reaction (OER) was obtained using dipping-thermal decomposition method. To improve the stability of the oxide film electrode, Polytetrafluoro ethylene(PTFE) and Perfluorosulfonic acid-PTFE Copolymer were used as additive. And the electrocatalytic activity for OER of different film electrodes were studied in 30%KOH solution.It was showed that the activity of Ni-Co-O compound oxide film electrode was not reduced after the additive was introduced. Additionally, the electroactivity of the oxide film was increased prepared with the one without additive after electrolysis for 6h. Furthermore, the overpotential,ηO 2, of the (Perfluorosulfonic acid-PTFE Copolymer) Ni-Co-O oxide film electrode was increased only 20mV, indicating the higher catalytic activity. The EDS experiment demonstrated that the obtained (Perfluorosulfonic acid-PTFE Copolymer) Ni-Co-O oxide film electrode possessed the structure just as the spinel, and the roughness factor of film electrode was also large. It was clear that the prepared compound oxide film electrode had its potential application as the anode material for industrial alkaline water electrolysis.