Designing highly efficient and cheap nanocatalysts for room-temperature hydrolysis of ammonia borane (AB) is of great significance for their real application in hydrogen (H2)-based fuel cells. Here, we report a kind of noble metal (NM)-free hybrid nanocatalysts composed of heterostructured Cu@CuCoOx nanoparticles and a graphene oxide support (denoted as Cu@CuCoOx@GO) and demonstrate their high catalytic performance toward the hydrolysis of AB. By rationally controlling synthetic parameters, we find that optimum Cu0.3@Cu0.7CoOx@GO achieves a superior catalytic activity with a turnover frequency of 44.6 molH2 molM-1 min-1 in H2O and 98.2 molH2 molM-1 min-1 in 0.2 M NaOH, better than most of previously reported NM-free nanocatalysts. This catalyst also discloses a very low activation energy (Ea) of 35.4 kJ mol-1. The studies on catalytic kinetics and isotopic experiments attribute the high activity to synergistically structural and compositional advantages of Cu0.3@Cu0.7CoOx@GO, which kinetically accelerates the oxidative cleavage of OH bond in attacked H2O (the rate-determining step of the hydrolysis of AB). This study thus provides an opportunity for rational design of cheap NM-free nanocatalysts for H2 production from chemical H2-storage materials.
Keywords: Ammonia borane; Catalytic kinetics; CuCo; Heterogeneous catalyst; Hydrogen production.
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