Pt-Functionalized PdO Nanowires for Room Temperature Hydrogen Gas Sensors

In this work, we prepared a well-aligned palladium oxide nanowire (PdO NW) array using the lithographically patterned Pd nanowire electrodeposition (LPNE) method followed by subsequent calcination at 500 degrees C. Sensitization with platinum (Pt) nanoparticles (NPs), which were functionalized on PdO NWs through a simple reduction process, significantly enhanced the detection capability of the Pt-loaded PdO NWs (Pt-PdO NWs) sensors toward hydrogen gas (H-2) at room temperature. The well-distributed Pt NPs, which are known chemical sensitizers, activated the dissociation of H-2 and oxygen molecules through the spillover effect with subsequent diffusion of these products to the PdO surface, thereby transforming the entire surface of the PdO NWs into reaction sites for H-2. As a result, at a high concentration of H-2 (0.2%), the Pt-PdO NWs showed an enhanced sensitivity of 62% (defined as Delta R/R-air X 100%) compared to that (6.1%) of pristine PdO NWs. The Pt-PdO NWs exhibited a response time of 166 s, which was 2.68-fold faster than that of pristine PdO NWs (445 s). In addition, the Pt-PdO NWs responded to a very low concentration of H-2 (10 ppm) with a sensitivity of 14%, unlike the pristine PdO NWs, which did not exhibit any response at that concentration. These outstanding results are mainly attributed to a homogeneous decoration of Pt NPs on the surface of well-aligned PdO NWs. In this work, we demonstrated the potential suitability of Pt-PdO NWs as a highly sensitive H-2 sensing layer at room temperature.