boundary derived from the solid state bonding may serve as a hydrogen diffusion path as a result the storing and releasing of hydrogen may have a lower activation energy barrier below exemplary embodiments will be described in detail with reference to accompanying drawings so as to be easily realized by a person having ordinary knowledge in the art the inventive concept may be embodied in various forms without being limited to the exemplary embodiments set forth herein descriptions of well known parts are omitted for clarity and like reference numerals refer to like elements throughout u03b1 al 2 o 3 powder was sensitized a sensitization agent was prepared as follows 0 4 g of sncl 2 was dissolved and hydrolyzed in 34 ml of de ionized water to form white precipitation 3 ml of 1n hcl solution was then added into the sncl 2 solution such that the solution was totally clear as such the sensitization agent was obtained 2 g of u03b1 al 2 o 3 powder tm dar commercially available from daimei telecom eng co was impregnated into the sensitization agent and stirred at room temperature for 5 minutes such that the sn 2 ions were adsorbed on the u03b1 al 2 o 3 powder surface thereafter the suspension of the sensitized u03b1 al 2 o 3 powder was centrifuged to remove a liquid of the suspension for obtaining the sensitized u03b1 al 2 o 3 powder 30 ml of a 0 9n naoh solution 35 ml of a 2n nh 4 oh solution and 30 ml of 0 3n agno 3 were mixed to prepare a tollens 39 reagent the sensitized u03b1 al 2 o 3 powder was impregnated in the tollens 39 reagent and a solution of a chemical reducing.