Microporous carbon supported PdNi nanoalloys with adjustable alloying degree for hydrogen storage at room temperature

Porous carbon materials with a high specific surface area are ideal for hydrogen storage. However, hydrogen (H2) can generally only be stored at low temperatures at high hydrogen pressures, due to the weak van der Waals forces between the material and H2. In this work, PdNi nanoalloys loaded microporous carbons (MC) were obtained through impregnation and in-situ reduction. The influence of PdNi ratios and reduction temperature on the alloying degree of PdNi nanoalloys and hydrogen storage performance of composite materials were investigated. The XRD results indicated that the degree of alloying in PdNi nanoalloys increased with the Pd/Ni ratio increasing from 1 to 3 and the reduction temperature elevating from 400 degrees C to 800 degrees C. PdNi/MC-800 containing 3 wt% Pd and 1 wt% Ni and reduced at 800 degrees C displayed a relatively higher alloying degree of PdNi (25.88 %), and had a hydrogen storage capacity of 0.95 wt% and 1.22 wt% at 20 bar and 50 bar at room temperature, respectively, significantly higher than MC, Ni/MC, Pd/MC, and other PdNi/MC composites. Theoretical calculations and experimental results indicated that an increase in the degree of alloying in PdNi nanoalloys leaded to a stronger interaction between the metals and hydrogen molecules, which promoted charge transfer between Pd and H2, thereby enhancing the hydrogen spillover effect on the composite material. The findings demonstrate a positive correlation between the degree of alloying in PdNi nanoalloys supported on porous carbon and their hydrogen storage capacity at 298 K, offering guidance for the development of efficient hydrogen storage materials at room temperature.