Interlinked W₁₈O₄₉ Nanowires Network on FTO: An Advanced Sensing Architecture for Selective NO₂ Gas Sensing

This study introduces the direct growth of WO₃ and W₁₈O₄₉ nanowires on patterned fluorine-doped tin oxide (FTO) by a hydrothermal technique, obviating the necessity for traditional interdigitated electrode designs based on Pt, Ag, Au, or Cu. The resulting W₁₈O₄₉ nanowires network exhibits a distinctive interconnected morphology with an average diameter of 11 ± 1.80 nm that is reminiscent of clusters with structural linkages, thereby augmenting both surface area and electronic pathways. This architecture facilitates the selective detection of NO₂ gas with a significantly superior response value of ≈152 at 100 °C, in contrast to WO₃ nanowires, which exhibit a response of ≈110 under identical conditions. The W₁₈O₄₉ nanowires network further demonstrates quick response and recovery times of 9 and 20 s, respectively, compared to the WO₃ nanowires network, which has 24 and 31 s, respectively. Comparative analysis with WO₃ nanowires synthesized with and without the support of FTO scaffold underscores the advantages of this configuration. In contrast to powdered forms that generate nanowires without interconnectedness, direct growth on FTO results in a robustly networked nanowire structure crucial for enhanced gas sensing performance. These results establish W₁₈O₄₉ nanowires on patterned FTO as a prospective architecture for the high-performance, selective detection of NO₂.