Reversible NH3 capture on g-C3N5 ferroelectric nanosheet investigated by density functional theory

Two-dimensional materials are ideal candidates for gas capture due to their large specific surface area and rich electronic properties. In this study, the two-dimensional polar material g-C3N5 is selected to investigate the adsorptions of CO, CO2, NO, NO2, NH3, and CH4. The adsorption energies revealed that NO, CO, NO2, CO2, and CH4 are poorly adsorbed on g-C3N5 (−0.09 ∼ −0.22 eV). Interestingly, NH3 is well adsorbed on one of the g-C3N5 sides (−0.38 eV). In addition to adsorption energy, there is more charge transfer between NH3 and g-C3N5. This indicates that the g-C3N5 has a superior selectivity for NH3. Due to the intrinsic polarity of g-C3N5, the top and bottom surfaces in the z-axis have different adsorption capacities for NH3, so NH3 can be stored and released separately. Moreover, g-C3N5 is stable after adsorption, because the interaction between NH3 and g-C3N5 hardly affects the original properties of g-C3N5. The above results show that g-C3N5 is a good sensitive material for NH3 storage and release.