A highly active Pd clusters hosted by magnesium hydroxide nanosheets promoting hydrogen storage

Abstract

Liquid organic hydrogen carriers (LOHCs) represent promising candidates for large-scale hydrogen storage, yet the design of high-efficiency and low-cost catalysts on the dehydrogenation of LOHCs remains challenging. Herein, we develop a two-dimensional (2D) magnesium hydroxide nanosheet that hosts Pd clusters (Pd/Mg(OH)2) for the dehydrogenation of dodecahydro-N-ethylcarbazole (12H-NEC), an important reaction for H2 transportation. The catalyst boosts the activity up to a 12H-NEC conversion of 100 % and the hydrogen release of 5.72 wt% with a low metal loading of 0.5 wt%, while the hydrogen release on Pd/MgO is only 2.34 wt% with the conversion rate of 71 % under the same conditions. Coupling various characterization technologies (HAADF-STEM, EXAFS, EPR and In-situ DRIFTS) with DFT calculations, it was found that the work function of magnesium hydroxide nanosheets for the dehydrogenation reaction due to the strong metal-support interaction, which makes Pd species have better dispersion, forms Pdn+-OH stable Pd cluster and reduces the dehydrogenation barrier as well, thus enhancing the dehydrogenation performance and improving the hydrogen production greatly. This work provides a new promising way to design advanced dehydrogenation catalyst with high activity for the hydrogen storage.