Synthesis and multi-technique characterization of nickel loaded MCM-41 as potential hydrogen-storage materials

• The MCM-41 allowed a Ni loading in the structure of up to ≈10 wt.% without collapsing.
• The presence of different Ni species was verified by spectroscopic techniques.
• The isolated Ni species coordinated to framework oxygen generate Lewis acid sites.
• A low Ni loading have a positive effect on the hydrogen storage capacity of MCM-41.
• The highly dispersed and acid Ni species promote the presence of H2-favorable sites.

Ni/MCM-41 samples have been successfully prepared by wet impregnation method with different degrees of metal loading. Various techniques including X-ray diffraction, N2 adsorption–desorption, transmission electron microscopy, inductively coupled plasma atomic emission spectroscopy, electron microprobe analysis, UV–Vis diffuse reflectance spectra, infrared analysis, adsorption of pyridine coupled to infrared spectroscopy and hydrogen adsorption at 77 K at high and low pressure conditions were employed for the materials characterization. The Ni loading degree had a marked influence on the structural, chemical, acid and hydrogen storage properties of the samples. Thus, a low Ni loading favors the presence of highly dispersed Ni species responsible of the Lewis acidity. These species would promote hydrogen-favorable sites leading to a positive effect on the hydrogen storage capacity.

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