Mesoporous Ferrihydrite-Based Iron Oxide Nanoparticles as Highly Promising Materials for Ozone Removal

摘要

Gaseous ozone (O3) in the troposphere is considered to be one of the most harmful air pollutants in view of its high reactivity and immediate action to the surroundings, which causes both short- and long-term adverse health effect and also disrupts plant growth. Materials explored for eliminating O3 in several applications include activated carbon or carbon-promoted oxide materials, noble-metal-supported catalysts, and various transition-metal oxides. These materials have diverse drawbacks: they must often be deposited on high-surface-area metal oxides or mixed with organic additives to enhance their performance, they use expensive metal components, they are not very environmentally friendly, and they are not flexible enough to use as a common choice in a wide range of sectors. Herein, we report for the first time that the two-line ferrihydrite (2LFh) with accessible mesopores can be used as a potential candidate for O3 removal. The following aspects prompted us to consider mesoporous 2LFh (M2LFh) a judicial choice for O3 removal: 1) it possesses high surface area and, being in the ferrihydrite (Fh) phase, a much higher percentage of iron sites are at or near the surface than in the bulk;2) with accessible mesopores, Fh nanoparticles have the potential for high adsorption owing to an increased rate of mass transfer to the reactive iron sites, such as we recently reported for their high efficiency in rapidly removing organic contaminants in the air; and 3) as an oxyhydroxide of iron, Fh is environmentally friendly and can be applied in various sectors. We also show herein that the presence of Fh nanoparticles in disordered mesostructured iron oxide has a significant effect on the bulk and surface structure of the material and on the activity. Our findings can contribute toward designing Fh-based materials as new potential catalysts for rapid removal of O3 and its decomposition.