Selective adsorption of H2on N-doped ZnO nano-ribbons: First-principle analysis

摘要

Adsorption and gas-sensing properties of ZnO nano-ribbons (ZnO-NRs) in detecting H2 are investigated using density functional theory (DFT) combined with the non-equilibrium Green's function (NEGF) formalism. Several dopants (e.g., C, N and F) have been tested versus adsorption of Hn₂nmolecule and other gas molecules (e.g., Nn₂n, On₂n, Hn₂nO, Hn₂nS). The results of relaxation show the occurrence of chemisorption to occur only in cases of C- and N-doped samples. Selective chemisorption of H2 and On₂nmolecules are observed on N-doped ZnO-NRs. The chemisorption of On₂nis associated with the breaking of just one π-bond. Whereas, the chemisorption of Hn₂nis associated with a complete dissociation and a formation of donor states in the gap (i.e., it yields n-type doping) and has the ability to enhance the conductivity. These characteristics made N-doped ZnO-NRs suitable for high sensitivity and selectivity towards the detection of Hn₂ngas. Furthermore, the calculated IV-curves have paved the way for estimating the sensitivity and consolidated our results. Since the change of conductance is one of the main outputs of sensors, our findings will be useful in developing ZnO-based devices for hydrogen storage and detection.