The gas sensitivity of the W defect in WS₂ (V_W/WS₂) to five toxic gases—HCHO, CH₄, CH₃HO, CH₃OH, and CH₃CH₃—has been examined in this article. These five gases were adsorbed on the V_W/WS₂ surface, and the band, density of state (DOS), charge density difference (CDD), work function (W), current–voltage (I–V) characteristic, and sensitivity of adsorption systems were determined. Interestingly, for HCHO-V_W/WS₂, the energy level contribution of HCHO is closer to the Fermi level, the charge transfer (B) is the largest (0.104 e), the increase in W is more obvious than other adsorption systems, the slope of the I–V characteristic changes more obviously, and the calculated sensitivity is the highest. To sum up, V_W/WS₂ is more sensitive to HCHO. In conclusion, V_W/WS₂ has a great deal of promise for producing HCHO chemical sensors due to its high sensitivity and selectivity for HCHO, which can aid in the precise and efficient detection of toxic gases.

Pure and Se-doped GaN nanowires (NWs) are synthesized on Pt-coated Si(111) substrates via chemical vapor deposition. The GaN NWs exhibit a uniform density with an average diameter of 20–120 nm. The structure of the NWs is wurtzite hexagonal, and the growth direction is along [0001]. Field emission measurements show that the Se-doped GaN NWs possess a low turn-on field (2.9 V μm⁻¹) compared with the pure GaN NWs (7.0 V μm⁻¹). In addition, density functional theory calculations indicate that the donor states near the Fermi level are mainly formed through the hybridization between Se 4p and N 2p orbitals and that the Fermi level move towards the vacuum level. Consequently, the work functions of Se-doped GaN NWs are lower than those of pure GaN NWs.