Heterostructured Ni/NiO Nanocatalysts for Ozone Decomposition

Water vapor is one of the main factors that deactivate an ozone decomposition catalyst, which limits its applications under practical conditions. In this work, a heterostructured Ni/NiO nanocatalyst is synthesized using a citric sol–gel method, which displays 100% removal efficiency to 1000 ppm ozone at room temperature in a dry flow (space velocity 240 000 mL g–1h–1). Importantly, the removal efficiency is still >98% at a high relative humidity RH of 90% after 8 h of testing, which is twice the efficiency of the pure NiO nanoparticles. The high humidity resistance of the Ni/NiO nanocatalyst can be interpreted as the weak adsorption of water on its surface, as proven by H2O temperature-programmed desorption, X-ray photoelectron spectroscopy, and chemiluminescence (CL). Surface atomic models are also established to present the reaction path of ozone on a catalyst surface under high humidity. In addition, as a proof of concept, a heterostructured Ni/NiO foam monolithic catalyst has been synthesized with nearly 100% decomposition efficiency to 10 ppm ozone at RH 90%. Therefore, these results show the great potency of the Ni/NiO heterogeneous nanocatalyst for ozone removal in harsh environments and can improve the understanding of the ozone decomposition process on a catalyst surface under high humidity.