All-around coating of CoNi nanoalloy using a hierarchically porous carbon derived from bimetallic MOFs for highly efficient hydrolytic dehydrogenation of ammonia-borane

Abstract

Highly efficient and stable supported non-noble metal catalysts to realize the real-time evolution of hydrogen for the promising substitution of fossil fuels are urgently desired but are still greatly challenging to achieve. In this work, a highly dispersed ultrafine CoNi nanoalloy has been successfully enclosed within a hierarchically porous carbon which exhibits a unique core–shell metal@carbon structure through an in situ carbonized reduction approach by using bimetallic CoNi-MOF-74 as a self-sacrificed template. Note that the all-around interactions between the nanoalloy and carbon within such a unique hierarchically porous core–shell can effectively stabilize and activate the CoNi nanoalloy, meanwhile facilitating the fast mass transfer of substrate molecules. We found that the Co/Ni ratio of the original precursors of MOF-74 and the pyrolysis temperature can significantly meditate the catalytic performance of the derived composite catalysts. In particular, the synthesized catalyst, 10%-CoNi/HPC-400, showed the best catalytic activity and good stability for hydrogen evolution with a turnover frequency value (TOF) of 27.22 min⁻¹ at 323 K, which is higher than most reported non-noble metal catalysts and even some noble metal catalysts. The outstanding catalytic performance and durability of the composite catalysts were attributed to the synergic effect of the well-dispersed CoNi alloy and the unique hierarchical core–shell structure, which demonstrated the huge potential for AB hydrolysis in hydrogen storage applications.