Decoration of graphene with tetrametallic Cu@FeCoNi core–shell nanoparticles for catalytic hydrolysis of amine boranes

Magnetic tetrametallic core–shell Cu@FeCoNi nanoparticles (NPs) supported on graphene have been synthesized through a simple one-step in situ procedure using methylamine borane (MeAB) as a reducing agent. The use of MeAB is the key for making the well-defined tetrametallic core–shell NPs, as sodium borohydride (NaBH4) resulting in tetrametallic alloy NPs, and ammonia borane (AB) resulting in a mixture of monometallic Cu and Cu@FeCoNi NPs. Thanks to the core–shell structure, the Cu@FeCoNi/graphene NPs exhibit much higher catalytic performance toward hydrolysis of AB than their counterparts reduced by NaBH4 and AB. Among all the catalysts studied, Cu12.6@Fe9.8Co38.8Ni38.8/graphene displays the highest catalytic performance toward hydrolysis of AB, with a turnover frequency (TOF) value of 20.93 mol H2 per min per mol per catalyst, which is higher than that of most reported non-noble metal-based catalysts, and even some noble-metal based catalysts. Furthermore, the as-prepared NPs exhibit good durability and magnetic recyclability toward hydrolysis of AB and MeAB, which makes the practical recycling application of the NPs more convenient.