MXenes: Reusable materials for NH3 sensor or capturer by controlling the charge injection

NH3 is one of the most common resources in chemical industry, which is very harmful to the human body. Thus, it becomes highly desirable to design advanced materials for efficient NH3 sensor or capturer. However, one of the main challenge is the facile release of NH3 gas from substrates due to the tendency of NH3 strong interaction with many substrates. In this work, the interaction between NH3 and O-terminated semiconducting MXenes (M2CO2, M = Sc, Ti, Zr, and Hf) with different charge states is considered by using first-principles simulations. Our results reveal that the NH3 could be strongly adsorbed on M2CO2 with apparent charge transfer, which renders them the potential candidates as the NH3 sensor or capturer. In particular, the process of NH3 release could be simply realized by tuning the electrons injected into M2CO2. Taking Zr2CO2 as an example, it is highly selective towards NH3 against other common gas molecules, and the adsorption energy dramatically increases from −0.81 eV to −0.20 eV when extra two electrons are injected into the 3 × 3 Zr2CO2 sheet. Our study demonstrates that O-terminated semiconducting MXenes are excellent materials for NH3 sensor or capturer, with highly reversible release and capture by controlling the charge states on the system.