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The use of LiAlH 4 as a promising hydrogen storage material is limited by its high desorption temperature, slow kinetics, and poor reversibility. In the present work, the influence of the catalytic activity of Nb 2 O 5 and Cr 2 O 3 nanoparticles on the hydrogen sorption properties of LiAlH 4 was investigated. It was shown that Nb 2 O 5 was superior to Cr 2 O 3 in improving the dehydriding property. For instance, samples of LiAlH 4 doped with 1 and 2 mol % Nb 2 O 5 showed improvement in the onset desorption temperature with little decrease in hydrogen capacity, where approximately 6.9 wt % was released by 193 °C. Isothermal desorption results at 120 °C revealed that enhancements arising upon adding Nb 2 O 5 were almost 6À7 times that of pristine LiAlH 4 . Moreover, LiAlH 4 À2 mol % Nb 2 O 5 displayed a substantially reduced activation energy and enthalpy change for LiAlH 4 dehydrogenation. The results of the first rehydrogenation indicated that the amount of restored hydrogen for Nb 2 O 5doped samples was lower than that of samples with Cr 2 O 3 . XRD, FESEM-EDS, and XPS examinations suggested that finely dispersed Nb species with a range of valence states might contribute to the kinetic improvement by serving as active sites for nucleation and growth of dehydrogenated product.

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Abstract. Fadhli N, Farid M, Rafiuddin, Efendi R, Azrai M, Anshori MF. 2020. Multivariate analysis to determine secondary characters in selecting adaptive hybrid corn lines under drought stress. Biodiversitas 21: 3617-3624. The development of adaptive hybrid corn varieties under drought stress needs an effective selection. Multivariate analysis has been reported can increase the effectiveness of selection in plants by attaching the secondary characters in the selection. Therefore, this concept also can be applied to develop adaptive corn varieties under drought stress. The objectives of this study are to determine the main secondary characters and select the best hybrid lines adaptive to drought stress. The experiment was arranged by a nested design, where replications nested under two environmental conditions, namely normal and drought stress. The main factor was genotypes consisted of 30 genotypes and was repeated three times. Moreover, the observations of this research consisted of 20 variables. The result of this research showed that the weight of harvested cob was an effective secondary character as a selection criterion along with productivity in selecting adaptive maize genotypes under drought stress. The number of green leaves was the character outside of the yield component could be as an alternative secondary character besides the weight of harvested cob. The selection results based on the weight of the harvested cob and productivity resulted in 12 hybrid corn lines considered adaptive to drought stress.

Hydrogen storage capabilities of controlled synthesized ZnO-based nanostructures have been investigated. The microscopic results reveal that the products consist of hollow ZnO microspheres composed of nanowires, hollow Sb-doped nanospheres, and Al-doped nanobelts. Energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) give evidence that Sb and Al dopants are successfully substituted into nanospheres and nanobelts, respectively. The photoluminescence (PL) spectra exhibit a strong green emission band due to defects in nanostructures which lead to a significant role in the hydrogen storage applications. The hydrogen storage characteristics prove that the defects in nanostructures are responsible for higher hydrogen absorption. Among the nanostructures the maximum hydrogen storage capacity of about 2.94 wt % is achieved under the pressure of 5 MPa for Al-doped ZnO nanobelts, and about 81.6% of the stored hydrogen can be released under ambient pressure at 373 K. The highly reversible absorption/desorption reactions exhibit that Al-doped nanobelts are promising material for hydrogen storage.