Low-temperature chemical synthesis of intermetallic TiFe nanoparticles for hydrogen absorption

Abstract

Nanosizing of TiFe hydrogen storage alloy is conducted to facilitate its activation. Here, pure intermetallic TiFe nanoparticles (45 nm) were prepared using chemical reduction of oxide precursors at 600 °C, which is the lowest temperature ever used in chemical synthesis. This was achieved using a strong reducing agent (CaH 2 ) in a molten LiCl. When used for hydrogen absorption, the obtained nanoparticles surprisingly exhibited almost no hydrogen absorption. The results demonstrated that TiFe nanoparticles are more di cult to activate than the bulk powder because the oxidized surface layers of the nanoparticles become stabilized, which prevents the morphological change necessary for their activation.

Molten Salt Synthesis of Intermetallic Compound TiNi Nanopowder Passivated by TiOx Shell Prepared from NiTiO3 for Catalytic Hydrogenation

“…These values are summarized in Table 1 . A larger crystallite size TiNi with a smaller BET surface area was obtained in this study compared with our previous results of TiFe (46.2–65.2 nm, 13.9–20.0 m 2 /g) [ 24 , 25 ]. Because nickel oxides are more easily reduced than iron oxide because of the more thermodynamic stability of FeO than NiO [ 37 ], the rate of crystal growth for TiNi crystal particles in the reduction/alloying processes at 650 °C could be accelerated to form the final larger particles.…”

“…Therefore, it would be innovative to prepare titanium alloys directly from titanium oxides. We previously succeeded in preparing intermetallic compound TiFe powders from the oxide precursors, including TiO 2 [ 24 ] and FeTiO 3 [ 25 ] by directly reducing them and then alloying them simultaneously in highly reductive conditions of molten LiCl-CaH 2 at 600 °C. Under these conditions, hydride ions (H − ) or calcium metals that are produced from CaH 2 could as strong reducing agents to readily reduce the titanium oxide precursors at such a low temperature.…”

Enhancing the acidic oxygen evolution reaction performance of RuO2-TiO2 by a reduction-oxidation process

“…The precursor was then mixed with CaH 2 and LiCl at a weight ratio of precursor/CaH 2 /LiCl = 1/4/1. The mixed powder was positioned in a graphite crucible and heated under Ar gas at 700 • C for one hour [34]. Subsequently, the sample was crushed in a mortar, rinsed with HCl aqueous solution (0.1 M), and then distilled water to obtain the RuTi nanoparticles (NPs), Which denoted as RuTi.…”

Effect of regulating the different proportions of Zr to Mn elements on the hydrogen storage properties of titanium–iron–manganese–hydrogen storage alloys

“…TiFe alloy has attracted much attention because of its excellent properties including high hydrogen storage capacity (around 1.86 wt%), low cost and abundant reserves. [8][9][10][11][12][13] But the disadvantages of TiFe alloy are very clear. The difficult activation is the rst problem needed to be solved.…”