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SUMMARYThe Au/Porous silicon structure (Au/PS) was developed as hydrogen fuel cell. The use of a porous silicon filled with hydrochloric acid as a proton-conducting membrane and thin gold film as a catalyst in Au/PS/Si fuel cell is demonstrated. The devices were fabricated by first creating 10-20 mm thick porous silicon layer by anodization etching in a standard silicon wafer and then depositing the gold catalyst film onto the porous silicon. Using sodium borohydride (NaBH 4 ) solution as the fuel, generation of the open-circuit voltage of 0.55 V and the fuel cell peak power density of 13 mW cm À2 at room temperature was achieved. Moreover production of hydrogen by evolution (out-diffusion) of hydrogen from solid sodium borohydride during thermal annealing at 30-1201C was investigated. Data on the effective diffusion coefficient of the hydrogen in NaBH 4 were determined from intensity changes of infrared vibration peaks of B-H bond (2280 and 3280 cm À1 ), as a result of thermal annealing of NaBH 4 samples. The relatively high values of the diffusion coefficient of hydrogen, increasing from 1 Â 10 À6 cm 2 s À1 to 2 Â 10 À4 cm 2 s À1 suggest that a thermo-stimulated evolution process can be used for producing hydrogen from NaBH 4 .

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