• Ping Li

Articles written in Bulletin of Materials Science

• NbCl5 and CrCl3 catalysts effect on synthesis and hydrogen storage performance of Mg–Ni–NiO composites

Two kinds of novel materials, Mg–1.6 mol% Ni–0.4 mol% NiO–2 mol% MCl (MCl = NbCl5, CrCl3), along with Mg–1.6 mol% Ni–0.4 mol% NiO for comparison, were examined for their potential use in hydrogen storage applications, having been fabricated via cryomilling. The effects of NbCl5 and CrCl3 on hydrogen storage performance were investigated. A microstructure analysis showed that besides the main Mg and Ni phases, NiO and Mg2Ni phases were present in all samples. MgCl2 was only found in halide-doped samples and NbO was only found in NbCl5-doped samples after ball milling. The particle size decreased significantly after 7 h of cryomilling. MgH2, Mg2NiH4 and Mg2NiH0.3 were present in all the samples, while NbH2 was only observed in the NbCl5 -doped sample after absorption. The NbCl5-containing composite exhibited a low onset absorption temperature of 323 K, which was 10 K lower than that of the no-halide doped catalyst. It absorbed 5.32 wt% of hydrogen in 370 s at 623 K under 4 MPa hydrogen pressure and can absorb 90% of its full hydrogen capacity in 50 s. Having an onset desorption temperature of 483 K in vacuum, the NbCl5 -containing composite desorbed hydrogen faster than the no-halide doped sample. The hydriding–dehydriding kinetics performance of the CrCl3-doped sample did not improve, but it did exhibit a lower onset desorption temperature of 543 K under 0.1 MPa, which was 20 K lower than that of the no-halide doped sample. NbO, NiO and NbH2 played important roles in improving absorption and desorption performances.

• CO impurities effect on LaNi4.7Al0.3 hydrogen storage alloy hydrogenation/dehydrogenation properties

LaNi4.7Al0.3 alloy was prepared by vacuum induction melting in high purity helium atmosphere, and the ingot was pulverized into 200–400 mesh powder after annealing. X-ray diffraction (XRD) and scanning electron microscopies (SEM) were utilized to study the alloy morphology and phase structure. X-ray photoelectron spectroscopy (XPS) was used for surface analysis. The poisoned alloy was tested at 30 °C in the mixture gas by thermogravimetric and differential thermal analyses (TG + DTA). The hydrogen storage properties were studied by the pressure–composition–temperature test. The activated sample was completely deactivated after only 3 hydriding/dehydriding cycles in hydrogen containing 300 ppm CO at 30 °C, but hydrogen storage capacity did not degrade when tested at 80 °C. Additionally, two different steps appeared in the absorption processes. Combined with XRD, XPS and TG + DTA results, an explanation for this phenomenon is given.

• Hydrothermal growth of wheatear-shaped ZnO microstructures and their photocatalytic activity

A facile hydrothermal process was developed to synthesize novel wheatear-shaped ZnO microstructures at alow temperature (85$^{\circ}$C) without the assistance of any template agent. X-ray diffraction and field emission scanning electron microscopy were used to characterize the structure and morphology of the samples. Results showed that the length of the ‘wheatear’ was about 5.8 $\mu$m and the section width was 1.2 $\mu$m. The particles consisted of closely packed nanorods withaverage diameter of 100 nm. The growth of wheatear-shaped ZnO is very rapid and can be achieved in only 5 min. OH$^−$-driven oriented aggregation and multistep nucleation resulted in the formation of wheatear-shaped ZnO microstructures.The product had assembled open structures and it exhibited excellent photocatalytic activity in the degradation of methylorange under UV-light irradiation.

• # Bulletin of Materials Science

Volume 44, 2021
All articles
Continuous Article Publishing mode

• # Dr Shanti Swarup Bhatnagar for Science and Technology

Posted on October 12, 2020

Prof. Subi Jacob George — Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru
Chemical Sciences 2020