Exceptional High and Reversible Ammonia Uptake by Two Dimension Few-layer BiI₃ Nanosheets

The emission of NH3 into atmosphere is seriously harmful for human health and public safety, thus the capture and recovery of NH3 from ammonia emissions is highly desirable. In recent years, many kinds of solid adsorbents have been exploited to absorb NH3. 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 BiI3 nanosheets have been prepared from bulk BiI3 powder by a simple and efficient liquid phase exfoliation strategy using green solvents and then applied for the NH3 capture for the first time. The results show that the adsorption capacity of NH3 of BiI3 nanosheets reaches up to 22.6 mmol/g at 1.0 bar and 25 °C, which approaches the record value for NH3 adsorption. Importantly, the NH3 uptake in BiI3 nanosheets is completely reversible and no clear loss in uptake capacity is observed after 10 cycles of adsorption–desorption. Furthermore, the BiI3 nanosheets exhibit remarkable selectivity for the separation of NH3/CO2 at 70 °C with theoretical selectivity coefficient of 700, which is promising for the selective separation of NH3 and CO2 in hot tail gas of some industrial processes. Mechanism studies indicate that such superior NH3 capacity, excellent reversibility and remarkable selectivity are primarily attributed to the Bi3+-NH3 coordination interactions.