| In recent years, with the development of modern science and technology, the concepts of low carbon economy, green energy and environmental protection were gradually paid attention by people. Metal gallium, used as one of the main raw material of semiconductor, solar energy, magnetism and hydrogen energy, had an important value in the field of modern science and technology. The main purpose of this research was the application of gallium and gallium compound oxide in hydrogen generation and semiconductor gas sensitive materials, respectively. In order to determine the molten salt system and cathode materials in preparation of aluminum gallium alloys for hydrogen generation by molten salt electrolysis, the molar ratio of NaF to AlF3 in cryolite molten salt was 1.59 and the experiment temperature was 850°C. In Na3AlF6-AlF3-Al2O3 molten salt, tungsten or molybdenum, high-purity carbon and Al3+/Al were used as working electrode, auxiliary electrode and reference electrode, respectively. The electrochemical behaviors of Al3+ were studied by using cyclic voltammetry and chronopotentiometry. Potentiostatic electrolysis was performed to electrodeposit aluminum on tungsten or molybdenum, respectively. The microstructures of the cathode product were characterized by SEM and EDS, and the composition was determined by XRD. It was found that the electrochemical process of Al3+ was diffusion-controlled quasi-reversible process when the working electrode was tungsten or molybdenum. The diffusion coefficient of Al3+ was 0.93×10-5 cm2/s and 1.28×10-5 cm2/s on tungsten and molybdenum, respectively. The alloying reaction occured when Al3+ electrodeposited on the tungsten or molybdenum electrode. So tungsten or molybdenum was unfit as the cathode materials in preparation of alloys for hydrogen generation by molten salt electrolysis.Secondly, the cathodic processes of Al3+ and Ga3+ in Na3AlF6-AlF3-Al2O3-Ga2O3 molten salt were investigated by using cyclic voltammetry. The iron was used as working electrode in three-electrode system. After that, the aluminum oxide and gallium oxide were used as electrolytic material to Al-Ga alloys by molten salt electrolysis. And the hydrogen generation performance was investigated by alloys reaction with water. The results showed that the hydrogen generation was studied by hydrolysis reaction. The results showed that the preparation of Al-Ga alloys for hydrogen generation by molten salt electrolysis directly was feasible. And the alloys also had good hydrolytic properties; when the water temperature was 30?, alloys can react with water to product hydrogen quickly. The rate of hydrogen generation reached the highest at 5s. With the increase of water temperature, the hydrogen yield and hydrogen generation rate were also increasing. However, when water temperature was higher than 50?, the tendency of alloys hydrogen performance change was slow. So the preparation of Al-Ga alloys for hydrogen generation by molten salt electrolysis was worthy of attention because of its easy operation, low temperature, low energy consumption and environment friendly.CuGa2O4 precursors were prepared by coprecipitation method. With the results of XRD, SEM and other characterization techniques, the gas sensing properties of CuGa2O4 was investigated by different conditions. It turned out that under different working temperature, CuGa2O4 gas sensitive element only had sensitivity to trimethylamine in common gas such as ammonia, formaldehyde, trimethylamine and other 4 kinds of gases. And different conditions of precipitation agent, the pH of precipitation and heat treatment temperature had significant influence on the gas sensing properties of Cu Ga2O4. While the sensitivity of CuGa2O4(pH=7,700?,4h)was 51.6 by ammonia precipitant, CuGa2O4(pH=6,800? 4h) had better selectivity and higher sensitivity to trimethylamine by Sodium hydroxide as precipitant, the response to 1000 ppm trimethylamine reached 310.On the other hand, CuGa2O4 precursors were prepared by Sol-Gel method. According to the results of XRD, SEM and other characterization techniques, the gas sensing properties of CuGa2O4 under different heat treatment temperature and 6 kinds of gases were investigated. The results showed that when working temperature are 50 and 285?,CuGa2O4(600?,4h)exhibited good response to trimethylamine and acetone, respectively. The sensitivities were 6.7 and 2.8, respectively. In addition, the change of heat treatment temperature had a significant effect on the gas sensing properties of CuGa2O4. |
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