NH₃ capture and detection by metal-decorated germanene: a DFT study

We report an investigation of the adsorption of ammonia (NH₃) on pristine, alkali (Li, Na, K), alkaline earth (Mg, Ca), and transition metal (Sc, Pd, and Ag) decorated germanene using a first-principles approach based on density-functional theory (DFT). The most stable adsorption geometries, adsorption energies, and charge transfers of NH₃ adsorbed on pristine and metal-decorated germanene are thoroughly discussed. First, the NH₃ adsorption on pristine germanene was considered, and subsequently, the NH₃ adsorption on metal-decorated germanene was studied. Our calculations found that the NH₃ is weakly adsorbed on pristine germanene. All metals improved the adsorption properties of pristine germanene. In particular, Sc, Mg, and Li atoms showed significantly enhanced interactions between NH₃ and germanene. In general, the electronic and adsorption properties demonstrated that metal-decorated germanene is superior to pristine germanene for the adsorption of NH₃ molecules. Changes in the work function due to adsorption of NH₃ molecule on the metal-decorated germanene were also calculated. Adsorption energy and desorption time results show that Sc-decorated germanene could trap this dangerous molecule at room temperature. Graphical abstract: [Figure not available: see fulltext.]