N-doped carbon coated Ti3C2 MXene as a high-efficiency catalyst for improving hydrogen storage kinetics and stability of NaAlH4

The synthesis of highly stable catalysts for the de/hydriding kinetics and cycle stability of NaAlH4 is crucial. Herein, N-doped carbon coated two-dimensional layered Ti3C2 (Ti3C2/NC) catalyst was synthesized by a self-polymerization and heat-treatment method. Impressively, the Ti3C2/NC catalyst remarkably improves the dehydrogenation properties of NaAlH4 with dramatically enhanced dehydrogenation kinetics and stability. In detail, after adding 10 wt% Ti3C2/NC, the initial dehydrogenation temperature is lowered to 85 degrees C, 3.0 wt% hydrogen is liberated within 4 min at 140 degrees C, the first step of hydrogen desorption is completed in 57 min at 100 degrees C, and its capacity retention after 15 cycle tests can remain up to 96.3%. It can be found that in-situ formed Ti-species (Ti-0 and Ti3+) during ball milling and the interaction between pyridinic-N and Ti-0 are responsible for the enhanced hydrogen storage performance of NaAlH4. Moreover, the carbon can efficiently stabilize Ti-0 species and results in high stability. This finding provides a new understanding of Ti-0-based MXene to catalyze the hydrogen storage for NaAlH4. (c) 2022 Elsevier Ltd. All rights reserved.

Automated summary

The synthesis of highly stable catalysts for NaAlH4 de/hydriding kinetics and cycle stability is crucial. In this study, N-doped carbon coated two-dimensional layered Ti3C2 (Ti3C2/NC) catalyst was synthesized and showed remarkable improvement in the dehydrogenation properties of NaAlH4, with enhanced dehydrogenation kinetics and stability. The formation of Ti-species during ball milling and the interaction between pyridinic-N and Ti-0 were found to be responsible for the enhanced hydrogen storage performance of NaAlH4.