| Description |
In recent years, hydrogen production and storage has attracted a lot of attention in both academia and industry due to its variety of applications in the energy sector. In this review, we attempt to list various methods of producing hydrogen from different sources of materials followed by the description of most recent developments in the materials perspective. We explain the role of nanotechnology in making the hydrogen production technology a viable and cost effective process. The chemical reaction cycle, mechanism and configurations of various methods of hydrogen production are elaborated in Part I of this thesis. Among the materials for chemical methods, aluminum could be utilized as an efficient and environmental friendly energy carrier via the production of hydrogen from water. However, it requires the reaction between aluminum and water to be complete, controllable and does not require the involvement of acids and/or alkali. Such direct reaction between aluminum and neutral water, once considered impractical due to the passivation of aluminum surface in water, is enabled with the relatively recent use of catalytic gallium-based liquid alloys. In this paper we have examined the roles of different elements (Ga, In, Sn, Zn, Bi) in this type of alloy and how their compositions affect the aforementioned reaction between aluminum and water. Besides the compositions of alloys, we have also studied the activation process between the liquid alloys and aluminum powders, as well as the storage process both before and after the activation. The rate of hydrogen production from each aluminum-water reaction was measured as a function of time. The whole research is discussed in Part II of this thesis. As photocatalysts for water splitting, CuBO2, CuAlO2, CuBO2/TiO2 heterojunction and CuAlO2/TiO2 heterojunction are synthesized and tested. All these materials exhibit positive water-splitting capability with a solution environment of 0.05M Na2S·9H2O as a hole scavenger and 0.1M NaOH as a pH modifier under simulated AM 1.5 standard sun light. The group with heterojunction CuAlO2/TiO2 shows an average hydrogen production rate of 0.509 mmol/min, 6.33% higher than the CuAlO2 group. The group with CuBO2 shows an average 0.979 mmol/min hydrogen production rate, the highest rate among all groups, 104.38% higher than the CuAlO2 group. The details of our work on photoelectrolysis are studied in Part III of this thesis. |
