Nanoconfined and <i>in Situ</i> Catalyzed MgH<sub>2</sub> Self-Assembled on 3D Ti<sub>3</sub>C<sub>2</sub> MXene Folded Nanosheets with Enhanced Hydrogen Sorption Performances.
basic_science · Level V
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- Record sourced from PubMed, PMID 34699176.
- Also identified by DOI 10.1021/acsnano.1c08343.
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Abstract
MXenes are considered as potential support materials for nanoconfinement of MgH<sub>2</sub>/Mg to improve the hydrogen storage properties. However, it has never been realized so far due to the stacking and oxidation problems caused by unexpected surface terminations (-OH, -O, <i>etc</i>.) on MXenes. In this study, hexadecyl trimethylammonium bromide was used to build a 3D Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> architecture of folded nanosheets to reduce the stacking risk of flakes, and a bottom-up self-assembly strategy was successfully applied to synthesize ultradispersed MgH<sub>2</sub> nanoparticles anchored on the surface of the annealed 3D Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> (Ti-MX). The composite with a 60 wt % loading of MgH<sub>2</sub> NPs, 60MgH<sub>2</sub>@Ti-MX, starts to decompose at 140 °C and is capable of releasing 3.0 wt % H<sub>2</sub> at 150 °C within 2.5 h. In addition, a reversible capacity up to 4.0 wt % H<sub>2</sub> was still maintained after 60 cycles at 200 °C without obvious loss in kinetics. <i>In situ</i> high-resolution TEM observations of the decomposition process together with other analyses revealed that the nanosize effect caused by the nanoconfinement and the multiphasic interfaces between MgH<sub>2</sub>(Mg) and Ti-MX, especially the <i>in situ</i> formed catalytic TiH<sub>2</sub>, were main reasons accounting for the superior hydrogen sorption performances.