Pt-Functionalized PdO Nanowires for Room Temperature Hydrogen Gas Sensors.

ABSTRACT

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 °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 (H2) at room temperature. The well-distributed Pt NPs, which are known chemical sensitizers, activated the dissociation of H2 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 H2. As a result, at a high concentration of H2 (0.2%), the Pt-PdO NWs showed an enhanced sensitivity of 62% (defined as Δ R/ Rair × 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 H2 (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 H2 sensing layer at room temperature.