In situ facile synthesis of bimetallic CoNi catalyst supported on graphene for hydrolytic dehydrogenation of amine borane

摘要

Well dispersed magnetically recyclable bimetallic CO_xNi_(1-x) (x = 0, 0.1, 0.3, 0.5, 0.7, 0.9, 1) nanoparticles (NPs) supported on graphene have been synthesized via a facile in situ one-step procedure, using the mixture of sodium borohydride (NaBH_4) and methylamine borane (MeAB) as the reducing agent under ambient condition. These NPs were composition dependent for catalytic hydrolysis of amine boranes. Among all the CoNi/graphene catalysts tested, the Co_(0.9)Ni_(0.1)/graphene NPs exhibit the highest catalytic activity toward hydrolysis of AB with the turnover frequency (TOF) value of 16.4 (mol H_2 min~(-1) (mol catalyst)~(-1)), being higher than that of most reported non-noble metal-based NPs, and even many noble metal-based NPs. Moreover, the activation energy (E_a) value is 13.49 kJ/ mol, which is the second lowest value ever reported for catalytic hydrolytic dehydrogenation of ammonia borane, indicating the superior catalytic performance of the as-synthesized Co_(0.9)Ni_(0.1)/graphene catalysts. Additionally, Compared with other reducing agents, such as NaBH_4, AB, MeAB, and the mixture of NaBH_4 and AB, the as-synthesized Co_(0.9)Ni_(0.1)/graphene catalysts reduced by the mixture of NaBH_4 and MeAB exert the highest catalytic activity. The Co_(0.9)Ni_(0.1) NPs supported on graphene exhibit higher catalytic activity than catalysts with other conventional supports, such as SiO_2, carbon black, and γ-Al_2O_3. Furthermore, the as-synthesized Co_(0.9)Ni_(0.1)/graphene NPs show good recyclability and magnetically reusability for the hydrolytic dehydrogenation of amine boranes, which make the practical reusing application of the catalysts more convenient.