Constructing Mg 2 Co-Mg 2 CoH 5 nano hydrogen pumps from LiCoO 2 nanosheets for boosting the hydrogen storage property of MgH 2 .

Herein, an active positive electrode material, LiCoO 2 nanosheets, was synthesized via a two-step method, which demonstrated a remarkable catalytic effect for the hydrogen storage property of MgH 2 . Incorporated with LiCoO 2 nanosheets, MgH 2 started to release hydrogen at 180 °C and a desorption content as high as 5.5 wt% H 2 was attained within 60 min at 250 °C. The dehydrogenation activation energy was significantly decreased to 48.5 ± 0.4 kJ mol -1 , achieving a 68.9% reduction compared to MgH 2 . It was verified by microstructural studies that Li + served as an "anchor" to facilitate a uniform distribution of LiCoO 2 "boat" among the MgH 2 "ocean", benefitting the self-assembly of numerous Mg 2 Co-Mg 2 CoH 5 couples on the surface of MgH 2 during the cycling process. Meanwhile, the in situ formed Mg 2 Co-Mg 2 CoH 5 couples were not restricted to offering multiple channels for fast hydrogen diffusion but also worked as "nano hydrogen pumps" to accelerate Mg/MgH 2 hydrogen charging and discharging. This study provides an interesting example of effective cooperation between Li + and Co 3+ on improving the catalytic action toward MgH 2 . It shall shed light on efficient designing of high-efficient catalysts in hydrogen storage areas or other energy-related fields.