Hydrogen Storage Materials Releasing Hydrogen on UV Irradiation

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K06976
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Energy engineering
• Research Institution: Nihon University
• Principal Investigator: NISHIMIYA Nobuyuki 日本大学, 理工学部, 特任教授 (90283499)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 水素吸蔵合金 / 紫外光照射 / 水素利用

Outline of Final Research Achievements

MgH2 was admixed with a metal and/or an oxide and was heated in vacuo under UV irradiation. A composite consisting of 5 mass% of anatase-type titanium oxide released hydrogen at the lowest temperature. The peak temperature of the release of hydrogen was 648 K for neat MgH2, and that for the MgH2 composite was 588 K, where the lowering by 44 K was due to admixing itself and 16 K to irradiation. The lowering of the peak temperature was not enhanced by addition of more than one component, which suggested premature saturation of the lowering through equilibrium.
Hydrogen was released from hydrogenated ZrVFe by heating, instead of by irradiation, and was reacted with gaseous nitrogen as a model experiment. As expectedly, ammonia was formed. An additional knowledge was that a layer of gold on MgH2 fabricated by vacuum deposition exerted rectifying function to inhibit back occlusion of released hydrogen.

Free Research Field

無機材料化学

Academic Significance and Societal Importance of the Research Achievements

水素貯蔵材料に光を照射することによって水素放出が低温化されるという現象を発見したことに学術的意義がある。水素吸蔵に利用されていない水素収容サイトやエネルギー準位が光吸収によって利用可能になっている可能性が高く、光刺激による準安定状態形成の物理化学という領域を切り拓く端緒となる。
社会的には、水素放出温度が高温であるために実用が制約されてきたマグネシウム合金からの水素放出温度を下げられることを、繰り返し確認できたことに意義がある。結晶内の水素収容サイト以外に光刺激で水素の通り道となるサイトを設計することにより、実用領域の370 Kで水素を放出する軽量水素吸蔵合金を作り出す道が開かれた。