Discovery of Amorphous Iron Hydrides via Novel Quiescent Reaction in Aqueous Solution

• Published in: Scientific reports 2020-04, Vol.10 (1), p.6199-6199, Article 6199
• Main Authors: Taguchi, Kohei, Shinozaki, Kazuteru, Okumura, Hideyuki, Michioka, Chishiro, Yoshimura, Kazuyoshi, Ishihara, Keiichi N.
• Format: Article
• Language: English
• Subjects: 639/301/1023/1026; 639/301/357/551; Aqueous solutions; Chemical precipitation; Crystallization; Heat treatment; Heat treatments; Humanities and Social Sciences; Hydrogen; Iron; multidisciplinary; Nanotechnology; Science; Science (multidisciplinary); Thermal properties
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-020-63124-2

Novel amorphous iron hydrides (AIHs) are synthesized for the first time under ambient conditions by employing novel “quiescent reaction”, without stirring for mixing solutions, during a conventional aqueous reduction-precipitation process. The kind and morphology of AIHs are dependent on the processing condition, where two types are found, with one form consisting of a tangle of uniform nanowires and the other being granular in nature. Both AIHs undergo transformation to crystalline α-Fe by heat treatment at 600 °C. The nanowire AIH exhibits the hydrogen content of 0.10 wt%, while the granular AIH of 0.22 wt%. Their magnetic and thermal properties are accordingly different, and the non-diffusive hydrogen contributes to stability of AIHs. It is strongly suggested that, by use of quiescent reaction, iron-hydrogen clusters are formed and preserved at an early stage of precipitation reaction, and subsequently aggregated into novel AIHs, preventing α-Fe crystallization. Hence, the AIHs would be categorized as metastable hydrides stabilized with iron-hydrogen clusters. In addition, newly discovered quiescent reaction in aqueous solution, from which unprecedented AIHs are derived, sheds new light on fundamental and essential aqueous reaction.