Abstract
The high desorption temperature and slow desorption kinetics of MgH2 makes it less competitive for future mobile applications; using a catalyst accompanied by mechanical milling seems to be a good solution to overcome those problems. Therefore, the addition of TiO2 and NiO to MgH2 accompanied by 15 h of mechanical milling was considered in this study. The phase constituent and hydrogen desorption of the powder mixture were investigated using X-ray diffraction (XRD) and a Sievert-type apparatus, respectively. XRD results showed that after milling, no binary or ternary compounds were formed, but hydrogen desorption time decreased and the desorbed hydrogen content increased. It seems that the increase in desorbed hydrogen was related to the simultaneous catalytic effect of TiO2 and NiO as well as mechanical milling. The results showed that the addition of both catalysts can improve the hydrogen desorption behavior of MgH2-based nanocomposite compared to the addition of only one catalyst of the same amount.
Highlights
Nowadays, it is a known fact that fossil fuels cause a series of ecological problems
The results showed that the addition of both catalysts can improve the hydrogen desorption behavior of MgH2based nanocomposite compared to the addition of only one catalyst of the same amount
We investigated the hydrogen desorption properties of MgH2–TiO2– NiO, as well as MgH2–TiO2 and MgH2–NiO nanocomposites
Summary
It is a known fact that fossil fuels cause a series of ecological problems. Polanski et al [16] ball-milled MgH2 with Cr2O3, Fe3O4, Fe2O3 and TiO2 for 20 h They reported that among all the oxide additives, TiO2 showed the best kinetics in desorption. [31] ball milled MgH2 with 5 wt% of TiO2 and added expanded natural graphite They stated that the kinetics was improved and a good cyclability was observed. We investigated the hydrogen desorption properties of MgH2–TiO2– NiO, as well as MgH2–TiO2 and MgH2–NiO nanocomposites. In this regard, the phase constituent of the powder mixture after ball milling, morphology, size and distribution of the particles, and the hydrogen storage properties of the samples were studied. The mean crystallite size and the lattice micro strain of the particles were measured using the Williamson–Hall method [37]: bsamplecosh 1⁄4 Kk=d þ 2esinh; ð1Þ where bsample is the full width at half-maximum (FWHM) of the milled powder, h the position of the peak maximum, K the Scherrer constant (about 0.9), k the beam wavelength, d the crystallite size, and e the lattice micro
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