Hydrogen is gaining a great deal of attention as an energy carrier as well as an alternative fuel. Interest in the use of hydrogen is based on its clean burning qualities, its potential for domestic production, and high efficiency of FCV (2–3 times that of conventional gasoline ICE). Hydrogen is one of the most abundant elements on earth and when used in a fuel cell, the sole by-product is water.
1. Hydrogen production
Hydrogen can be produced using various ways, such as steam reforming of methane, Electrolysis, gasification of coal and biomass, thermochemical water splitting, water decomposition by photocatalytic and photoelectrochemical systems, etc. Among them, using solar energy for hydrogen production, as a clean and abundant source of hydrogen, is a better option for long-term hydrogen production. However, current solar cells are too expensive for hydrogen generation. An additional limitation is that most solar cell materials such as SiO2, CdTe, and GaAs are unstable in aqueous solutions. Semiconducting metal oxides, cheaper and more stable such as TiO2, exhibit novel properties that may make solar hydrogen production commercially viable. The most attractive semiconductor is nanostructured TiO2, because it is stable, non-corrosive, environmentally friendly, abundant, and cost effective. Many other metal oxides such as Fe2O3, TaO3 have also been investigated to be suitable.
2. Hydrogen storage
The small size of nanostructured materials has a strong influence on the kinetics of hydrogen adsorption and dissociation due to the increase in the diffusion rate as well as the decrease in the required diffusion length, so that the storage capacity is increased a lot.
3. Application materials
||Solar cell for hydrogen production
||Cheaper, stable, abundant, environmentally friendly|
||large specific surface area|