Ultrathin nanowire based on icosahedral W@Au12 and application as NO gas sensor

In this study, we used first-principles calculations to investigate the structural and electronic properties of an ultrathin nanowire formed by assembling icosahedral W@Au₁₂ clusters and its application as a NO gas sensor. An ultrathin nanowire with a diameter of about 5.52 Å was produced via the coalescence of icosahedral W@Au₁₂ clusters. The W@Au₁₂-based nanowire exhibited semiconducting properties with a direct band gap. Frequency analysis and molecular dynamics simulations indicated that the nanowire was particularly stable at T = 300 K. The nanowire chemisorbed a NO molecule with moderate adsorption energy, and the N atom in NO bonding with the Au atom was the most stable bond. Analysis of the Boltzmann distribution and transition state demonstrated that the most stable configuration was particularly likely to form. The electronic properties of the W@Au₁₂-based nanowire were changed dramatically by NO adsorption, with a transition from semiconducting to conducting behavior after NO adsorption. However, the adsorption of CO₂, CH₄, O₂, H₂, N₂, or H₂O molecules had little effect on the conductance of the nanowire. Our results indicated that the W@Au₁₂-based nanowire sensor was highly sensitive and selective. The recovery time for the nanowire-based NO sensor was about 12 s at T = 300 K. Therefore, due to its moderate adsorption energy, significant change in the electric conductivity, and very rapid recovery time, we conclude that the W@Au₁₂-based nanowire is a promising gas sensor with high performance at NO detection.