Ni–Cu–Co Grid-like Hydroxyl Oxide Ammonia Oxidation Reaction Catalyst Supported on Carbon Nanotubes

Ammonia is a very promising source of carbon-free chemical energy. However, current electrochemical technologies for ammonia use are limited by the kinetically sluggish and easily toxic catalyst surface ammonia oxidation reaction (AOR). Here, we report an AOR catalyst in which Ni, Cu, and Co are highly dispersed on single-walled carbon nanotubes (CNTs) (Ni–Cu–Co/CNT) in the form of hydroxides and hydroxyl oxides by using a one-step solvothermal method. Ni–Cu–Co/CNT, with Co doping and a support of the CNT, has shown highly efficient catalytic activity for the AOR in alkaline media. Cyclic voltammetry tests show that the catalyst has an onset potential of 0.3 V vs Ag/AgCl and a peak current of 96 mA cm–2. Density functional theory suggests that the addition of Co and a CNT leads to a lower energy barrier for the critical AOR step, which can be attributed to intermetallic synergy and metal–support interactions formed by the CNT.