Trimesic acid-Ni based metal organic framework derivative as an effective destabilizer to improve hydrogen storage properties of MgH2

Herein, a new type of trimesic acid-Ni based metal organic framework (TMA-Ni MOF) was synthesized and then, its derivative Ni@C was introduced into MgH2 as destabilizer through high energy ball milling to prepare a Mg-Ni@C-H composite. X-ray diffraction analyses indicate the formation of Mg2Ni/Mg2NiH4 as major phases after dehydrogenation/rehydrogenation of the composite, respectively. Two hydrogen absorption plateaus are observed in the Mg-Ni@C-H composite, corresponding to the hydrogenation of Mg and Mg2Ni, with the enthalpy change values of -75.8 and -52.3 kJ mol(-1) H-2 respectively. Thus, it can be concluded that a destabilization effect is brought by Ni@C on thermodynamic properties of MgH2. In addition, the hydriding/dehydriding kinetics of MgH2 is notably accelerated with the addition of Ni-based MOF derivative. The activation energy values of both hydrogen absorption and desorption are significantly lowered down with the assistance of Ni@C. Moreover, stable hydrogen de/absorption capacity and kinetics are remained during 25 cycles of high-rate re/dehydrogenation, which can be ascribed to the carbon-wrapped structure of the composite, with which the aggregation of the nanosized particles can be evidently avioded. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

A new type of trimesic acid-Ni based metal organic framework (TMA-Ni MOF) was synthesized, and its derivative Ni@C was introduced into MgH2 through high energy ball milling to prepare a Mg-Ni@C-H composite, which showed accelerated hydrogen absorption/desorption kinetics and reduced activation energy. The carbon-wrapped structure of the composite prevented aggregation of nanosized particles, ensuring stable hydrogen capacity and kinetics during high-rate cycling.