Abstract
Well dispersed magnetically recyclable bimetallic CoNi nanoparticles (NPs) supported on the reduced graphene oxide (RGO) were synthesized by one-step in situ coreduction of aqueous solution of cobalt(II) chloride, nickel (II) chloride, and graphite oxide (GO) with ammonia borane (AB) as the reducing agent under ambient condition. The CoNi/RGO NPs exhibits excellent catalytic activity with a total turnover frequency (TOF) value of 19.54 mol H2 mol catalyst−1 min−1and a low activation energy value of 39.89 kJ mol−1at room temperature. Additionally, the RGO supported CoNi NPs exhibit much higher catalytic activity than the monometallic and RGO-free CoNi counterparts. Moreover, the as-prepared catalysts exert satisfying durable stability and magnetically recyclability for the hydrolytic dehydrogenation of AB, which make the practical reusing application of the catalysts more convenient. The usage of the low-cost, easy-getting catalyst to realize the production of hydrogen under mild condition gives more confidence for the application of ammonia borane as a hydrogen storage material. Hence, this general method indicates that AB can be used as both a potential hydrogen storage material and an efficient reducing agent, and can be easily extended to facile preparation of other RGO-based metallic systems.
Highlights
Hydrogen, as a globally accepted clean and environmentally friendly fuel, has attracted widespread research concerns and interests [1]
We have discovered that the CoNi/reduced graphene oxide (RGO) exhibits excellent catalytic activity in hydrolysis of ammonia borane (AB) for hydrogen generation
Chemical reduction methods are widely employed for the synthesis of NPs in solution phase in the presence of surfactant [43], whose presence on the surface diminishes the activity to some extent by blocking some of the active sites when NPs are employed as a catalyst [44]
Summary
As a globally accepted clean and environmentally friendly fuel, has attracted widespread research concerns and interests [1]. The aggregation of metal NPs during the catalytic process due to the high surface energies and magnetic properties is the main impediment to restraint their development [36]. To solve this problem, various surfactants and substrates are successfully utilized to obtain catalysts with preferable dispersity [12,13,14]. We have discovered that the CoNi/RGO exhibits excellent catalytic activity in hydrolysis of AB for hydrogen generation Separation of this catalyst from reactant liquid is quite simple by using a magnet, as CoNi/RGO has an excellent magnetic property. This mild and rapid strategy provides great potential for application of ammonia borane as an on-board hydrogen medium
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