Surface Engineering of Hydrides

The surface of hydrogen-absorbing materials provides the contact point for interactions between gas-solid and liquid-solid phases. A typical example of the role and function of the surface is the transition of gaseous hydrogen at the metal hydride surface where it dissociates to monatomic hydrogen which is then located in the interstitial sites of the crystalline lattice (see Chapter 4.4). 

Engineering applications such as hydrogen storage in metal hydrides, the nickel-metal hydride rechargeable battery (Ni-MH), and the proton exchange membrane fuel cell (PEMFC) are basically dependent on the surface properties and characteristics. 

In this chapter, the transition of H2 (gaseous hydrogen) to (proton), H to 

H° (protium), and H (protide) to H+ is described from the surface interaction viewpoints in engineering applications. These four states of hydrogen are described in Chapter 4.4. 

Transition of the four different states of hydrogen, as described in Chapter 4.4, occurs at the gas-solid and liquid-solid interface as illustrated below  

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