Aerosol-Assisted CVD-Grown WO₃ Nanoneedles Decorated with Copper Oxide Nanoparticles for the Selective and Humidity-Resilient Detection of H₂S

A gas-sensitive hybrid material consisting of Cu₂O nanoparticle-decorated WO₃ nanoneedles is successfully grown for the first time in a single step via aerosol-assisted chemical vapor deposition. Morphological, structural, and composition analyses show that our method is effective for growing single-crystalline, n-type WO₃ nanoneedles decorated with p-type Cu₂O nanoparticles at moderate temperatures (i.e., 380 °C), with cost effectiveness and short fabrication times, directly onto microhot plate transducer arrays with the view of obtaining gas sensors. The gas-sensing studies performed show that this hybrid nanomaterial has excellent sensitivity and selectivity to hydrogen sulfide (7-fold increase in response compared with that of pristine WO₃ nanoneedles) and a low detection limit (below 300 ppb of H₂S), together with unprecedented fast response times (2 s) and high immunity to changes in the background humidity. These superior properties arise because of the multiple p–n heterojunctions created at the nanoscale in our hybrid nanomaterial