Highly efficient hydrogen production from hydrolysis of ammonia borane over nanostructured Cu@CuCoO_x supported on...

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@CuCoO_x nanoparticles and a graphene oxide support (denoted as Cu@CuCoO_x@GO) and demonstrate their high catalytic performance toward the hydrolysis of AB. By rationally controlling synthetic parameters, we find that optimum Cu_0.3@Cu_0.7CoO_x@GO achieves a superior catalytic activity with a turnover frequency of 44.6 mol_H2 mol_M^-1 min^-1 in H₂O and 98.2 mol_H2 mol_M^-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 (E_a) 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 Cu_0.3@Cu_0.7CoO_x@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.