In Situ Generated Cu/Nb Catalytic Interfaces for Enhancing MgH₂ Hydrogen Storage.

Area of Science:

• Materials Science
• Catalysis
• Hydrogen Storage

Background:

• Magnesium hydride (MgH2) faces challenges in hydrogen release temperature, kinetics, and cycling performance.
• Developing efficient catalysts is crucial for improving MgH2 hydrogen storage capabilities.

Purpose of the Study:

• To develop a high-performance catalyst for MgH2.
• To investigate the catalytic effect of niobium-based bimetallic compounds on MgH2.
• To improve hydrogen absorption/desorption kinetics and cycling stability of MgH2.

Main Methods:

• Synthesis of niobium-based bimetallic compound catalyst CuNb2O6.
• Preparation of MgH2/CuNb2O6 composite material.
• Hydrogen absorption and desorption measurements at various temperatures and times.
• Determination of apparent activation energy for hydrogen release.
• Cyclic testing for stability assessment.
• Catalytic mechanism studies, including in situ reconstruction and heterojunction analysis.

Main Results:

• MgH2/CuNb2O6 composite achieved 4.28 wt % hydrogen uptake in 10 min at 100 °C and 2 wt % at 50 °C in 60 min.
• Exceptional mid-temperature hydrogen release: 4.65 wt % in 20 min at 225 °C.
• Apparent activation energy for hydrogen release reduced by approximately 66.4% compared to ball-milled MgH2.
• Stable hydrogen storage capacity of 5.21 wt % after 50 cycles.
• In situ reconstruction of catalytically active species and formation of Mg2Cu@NbO2 heterojunction observed.

Conclusions:

• CuNb2O6 demonstrates excellent catalytic performance for MgH2 hydrogen storage.
• The MgH2/CuNb2O6 composite exhibits superior hydrogen absorption and desorption kinetics and improved cycling stability.
• Synergistic catalytic effects between Cu and Nb species at the Mg2Cu@NbO2 heterojunction interface are key to enhanced performance.
• This study offers a promising strategy for designing efficient catalysts for magnesium-based hydrogen storage.