Exceptional High and Reversible Ammonia Uptake by Two Dimension Few-layer BiI Nanosheets.

The emission of NH into atmosphere is seriously harmful for human health and public safety, thus the capture and recovery of NH from ammonia emissions is highly desirable. In recent years, many kinds of solid adsorbents have been exploited to absorb NH. However, these materials do not show the advantages of high uptake capacity and good recyclability at the same time. Here, nontoxic and low cost few-layer BiI nanosheets have been prepared from bulk BiI powder by a simple and efficient liquid phase exfoliation strategy using green solvents and then applied for the NH capture for the first time. The results show that the adsorption capacity of NH of BiI nanosheets reaches up to 22.6 mmol/g at 1.0 bar and 25 °C, which approaches the record value for NH adsorption. Importantly, the NH uptake in BiI nanosheets is completely reversible and no clear loss in uptake capacity is observed after 10 cycles of adsorption-desorption. Furthermore, the BiI nanosheets exhibit remarkable selectivity for the separation of NH/CO at 70 °C with theoretical selectivity coefficient of 700, which is promising for the selective separation of NH and CO in hot tail gas of some industrial processes. Mechanism studies indicate that such superior NH capacity, excellent reversibility and remarkable selectivity are primarily attributed to the Bi-NH coordination interactions.