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In this study, two different nano-structured samples of the FeTi compound were prepared by mechanical alloying and mechanical grinding. For these samples, kinetics of the initial rate of hydrogen absorption, and the equilibrium hydrogen pressure as a function of hydrogen concentration were measured. Mechanical alloying of Fe and Ti atoms produced the FeTi compound powder samples with microstructures of a mixture of nano-structured FeTi grains and amorphous phases. This sample exhibited a high initial rate of hydrogen absorption even at 298 K, however, a strongly reduced hydrogen storage capacity. Mechanical grinding of the FeTi produced samples of particles with a particular microstructure: surface layers with a mixture of nano-structured FeTi grains and amorphous phases, and a single crystalline phase of FeTi below the surface layers for each particle. This sample exhibited a high initial rate of hydrogen absorption without a significant reduction of the hydrogen storage capacity compared with that of the standard FeTi sample. This mechanical grinding treatment was found to be an effective method of surface modification to improve the initial activation of the FeTi hydrogen storage alloy.

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The superhydrophilization of a silicon (Si) surface by atmospheric-pressure plasma jet irradiation was analyzed by time-of-flight secondary ion mass spectrometry (TOF-SIMS). The Si surface was irradiated with an atmosphericpressure argon (Ar) plasma jet in air for 5 s. The contact angle of a water drop on the Si surface decreased from 77 to 7 • as a result of plasma jet irradiation, meaning that the Si surface became superhydrophilic. TOF-SIMS analysis indicated that the superhydrophilization was due to the removal of hydrophobic polydimethyl siloxane (PDMS) adsorbed on the Si surface and the increase in the amount of the hydrophilic silanol (SiOH) group. Emission spectral analysis of the plasma jet indicated that the SiOH group was formed when hydroxyl (OH) radicals, generated by collisions between high-energy electrons in the plasma and water molecules in air, bond to Si atoms on the surface.