Ammonia borane methanolysis for hydrogen evolution on Cu3Mo2O9/NiMoO4 hollow microspheres

Catalytic methanolysis of ammonia borane (AB) is an integrated hydrogen storage-production technology with bright prospects; the development of robust and cheap catalysts is crucial for its wide applications. In this study, we developed heterostructured Cu3Mo2O9/ NiMoO4 hollow spheres comprised of nanoplatelets as catalysts for AB methanolysis. The Cu3Mo2O9/ NiMoO4 catalyst with the optimal Cu/Ni ratio exhibited robust reactivity with a turnover frequency (TOF) of 62.1 molhydrogen min-1 molcat -1, which is superior to other precious-metal-free cat-alysts ever reported in the literature. Based on the theoretical calculation results, it was found that the d band center of the heterostructured Cu3Mo2O9/ NiMoO4 catalysts exhibited an up shift compared to those of single Cu3Mo2O9 and NiMoO4, which was favorable for the chemisorption of the reactants. In addition, it was revealed that the active Ni and Cu sites in Cu3Mo2O9 /NiMoO4 catalysts were responsible for the adsorption and activation of CH3OH and AB, respectively. The rate-determining step of AB methanolysis over Cu3Mo2O9/NiMoO4 catalyst was identified, and a possible reaction mechanism was proposed. This study may provide a deeper understanding of the adsorption and activation behaviors of methanol and AB, cooperative roles of different active sites on the heterostructured catalyst, as well as the reaction mechanism, conducive to the rational design of inexpensive and high-performing catalysts for AB methanolysis for hydrogen production.