H₂ Plasma Reducing Ni Nanoparticles for Superior Catalysis on Hydrogen Sorption of MgH₂

Abstract

Highly fine, dispersive, and active catalysts are essential for lowering the operating temperature of MgH2, a promising high-capacity material for solid-state hydrogen storage. In this work, ultrafine Ni nanoparticles (2–6 nm) are synthesized from the precursor nickel acetylacetonate (C10H14NiO4) on the surface of MgH2 by H2 plasma reduction process, followed by further ball milling. The obtained composite could rapidly release more than 6.5 wt % H within 10 min at 275 °C. Even at a low temperature of 225 °C, up to 6 wt % H could be desorbed. The MgH2–Ni composite also exhibits excellent low-temperature hydrogenation kinetics and almost no capacity degradation over nine hydrogenation/dehydrogenation cycles. The significant improvement in the hydrogen-storage properties is attributed to the in situ formation of ultrafine and stable Mg2NiH0.3 nanocrystals during cycling. This work provides a convenient approach to synthesize ultrafine metal nanoparticles for catalytic applications in the field of high energy storage density hydride materials.

Short-Range Nanoreaction Effect on the Hydrogen Desorption Behaviors of the MgH2–Ni@C Composite

“…Additionally, the hydrogen desorption activation energy ( E a ) of the MgH 2 –5 wt % Ni@C composites is calculated as 78.09 kJ/mol based on the Johnson–Mehl–Avrami (JMA) model and Arrhenius equation (Figure S6). Compared with other catalysts, ,− the Ni@C catalyst in this work shows an enhanced catalytic performance. For example, the E a values of MgH 2 –Ni 3 Fe/BC and MgH 2 –10Ni­(acac) 2 are 102.01 and 112.1 kJ/mol, respectively.…”

Regulation of the integrated hydrogen storage properties of magnesium hydride using 3D self-assembled amorphous carbon-embedded porous niobium pentoxide

“…5B. Both MgH 2 + C-p-Nb 2 O 5 and MgH 2 + p-Nb 2 O 5 started to release hydrogen at 181 °C, which is lower than those MgH 2 + np-Nb 2 O 5 (200 °C), Mn 3 O 4 -doped MgH 2 (200 °C), 15 V 2 O 3 @C-doped MgH 2 (215 °C), 21 Na 2 Ti 3 O 7 NTs-doped MgH 2 (233.5 °C), 10 and Ni 3 (VO 4 ) 2 -doped MgH 2 (210 °C). 34 The addition of Nb 2 O 5 lowered the dehydrogenation temperature of MgH 2 .…”

“…3,4 Among different solid-state hydrogen storage materials, magnesium hydride (MgH 2 ) has attracted signicant attention because of its high hydrogen storage capacity (7.6 wt%), abundant earth reserves, and low cost; 5,6 however, the high working temperature and the slow kinetic performance hinder its applications. 7 Transition metals, [8][9][10] transition metal derivatives, [11][12][13][14][15][16] and carbon composites [17][18][19][20] have been proven to be ideal dopants to improve the hydrogen storage properties for MgH 2 . Liang et al 10 used ultra-ne nickel nanoparticles of 2-6 nm sizes to improve the hydrogen storage properties of MgH 2 and found that Ni nanoparticles reacted with Mg and H 2 to form Mg 2 NiH 0.3 /Mg 2 Ni during hydrogen uptake and discharge.…”

“…7 Transition metals, [8][9][10] transition metal derivatives, [11][12][13][14][15][16] and carbon composites [17][18][19][20] have been proven to be ideal dopants to improve the hydrogen storage properties for MgH 2 . Liang et al 10 used ultra-ne nickel nanoparticles of 2-6 nm sizes to improve the hydrogen storage properties of MgH 2 and found that Ni nanoparticles reacted with Mg and H 2 to form Mg 2 NiH 0.3 /Mg 2 Ni during hydrogen uptake and discharge. Mg 2 NiH 0.3 /Mg 2 Ni acted as a "hydrogen pump" to provide more hydrogen diffusion channels.…”

Constructing Mg2Co–Mg2CoH5 nano hydrogen pumps from LiCoO2 nanosheets for boosting the hydrogen storage property of MgH2

“…Particularly, transition metals and their compounds have shown effective catalytic action in improving the hydrogen storage performance of MgH 2 . [25][26][27] Cobalt, as a transition metal element with active 3d free electrons, numerous compounds, and tunable morphologies, has received significant attention as a catalyst for hydrogen storage materials. 28,29 For example, Liu et al prepared a multi-valence Co-based catalyst and found that the MgH 2 -Co@CNT composite only suffered a minor capacity loss after 50 cycles, which could be attributed to the in situ formed Co 3 MgC 0.5 .…”