Polyol Process Coupled to Cold Plasma as a New and Efficient Nanohydride Processing Method: Nano-Ni2H as a Case Study

Abstract

An alternative route for metal hydrogenation has been investigated: cold plasma hydrogen implantation on polyol-made transition metal nanoparticles. This treatment applied to a challenging system, Ni–H, induces a re-ordering of the metal lattice, and superstructure lines have been observed by both Bragg–Brentano and grazing incidence X-ray diffraction. The resulting intermetallic structure is similar to those obtained by very high-pressure hydrogenation of nickel and prompt us to suggest that plasma-based hydrogen implantation in nanometals is likely to generate unusual metal hydride, opening new opportunities in chemisorption hydrogen storage. Typically, almost isotropic in shape and about 30 nm sized hexagonal-packed Ni2H single crystals were produced starting from similarly sized cubic face-centred Ni polycrystals.

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“…This issue was also successfully explored on compacted (porosity of ~50%) polyolmade Nickel particles of ~25 nm diameter (Figure 9) to Ar (10 %)-H 2 (90%) using a microwave plasma (2.45 GHz) for 2 h of exposition [64] leading to the production of similarly Ni 2 H particles (Figure 10). Plasma power and gas pressure were kept constant at 180 W and 1 mbar, respectively.…”

“…Two populations of particles can be identified, the smallest and scarcest ones and the largest ones. Representative micrograph of each particle type is given for information, the smallest and the largest being fully indexed within the cubic Ni and hexagonal Ni2H structures, respectively (adapted from [64]). Despite all the highlighted added value of the so-called cold plasma hydrogen ion implantation metal hydride processing remains still confidential.…”

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“…Finally, Haj-Khlifa et al [ 51 ] use polyol-made nano-metals as starting materials for the production of crystallized nano-intermetallics by hydrogen cold plasma implantation. They evidence that the nanometric size of nickel particles, even compacted as a thick pellet (millimeter in thickness) allows the diffusion of atomic hydrogen and its interaction with nickel atoms to form, within optimized processing conditions, Ni 2 H nano-intermetallics crystallizing in a hexagonal structure, paving the way for an alternative route for the preparation of efficient substrates for solid hydrogen storage application.…”

“…They have been used also as starting matter for the fabrication of granular nanomaterials that are new by composition, structure, or microstructure, thanks to a judicious subsequent treatment, like oxidative [47,48] (or reductive [49,50]) annealing, cold plasma implantation [51] and reactive sintering [52,53].…”

Correction: Haj-Khlifa, S., et al. Polyol Process Coupled to Cold Plasma as a New and Efficient Nanohydride Processing Method: Nano-Ni2H as a Case Study. Nanomaterials 2020, 10, 136

“…The authors wish to make the following corrections to this paper [1]: there are two mistakes in this article [1]. In the last paragraph of Section 3-Results and Discussion, the sentence "Within relatively soft operating conditions almost pure granular Ni 2 H hydrides are produced reaching a hydrogen storage capacity of 1.7 wt %" should be "Within relatively soft operating conditions almost pure granular Ni 2 H hydrides are produced reaching a hydrogen storage capacity of 0.9 wt %".…”