Mechanochemical Synthesis of High Entropy Oxide Materials under Ambient Conditions: Dispersion of Catalysts via Entropy Maximization

The solid-solution metal oxide (NiMgCuZnCo)O is the first known high-entropy (HE) metal oxide synthesized, forming a poster child of the emerging high-entropy oxide materials, which is derived from high-temperature synthesis methodologies (>900 °C). In this work, we report the mechanochemical synthesis of this known HE metal oxide (NiMgCuZnCo)O under ambient conditions. The advantage of this approach was further demonstrated by the introduction of up to 5 wt % noble metal into (NiMgCuZnCo)O, as single atoms or nanoclusters, which showed good stability at high temperature and produced a high catalytic activity in the hydrogenation of atmospheric CO2 to CO. The latter work demonstrated the unique advantage of using HE materials to disperse catalysis centers.