Selective Detection of H₂ Gas in Gas Mixtures Using NiO-Shelled Pd-Decorated ZnO Nanowires

Hydrogen (H-2) gas is a green fuel, but its leakage during storage and transportation can lead to disasters due to its explosive nature. Here, a sensitive and selective H-2 gas sensor is developed that can detect H-2 in H-2/CO and H-2/NO2 gas mixtures. First, ZnO nanowires (NWs) are grown using vapor-liquid-solid growth. This is followed by atomic layer deposition-mediated growth of Pd nanoparticles (NPs) on the ZnO NWs and uniform deposition of a thin NiO shell layer (12 nm in thickness) over the Pd-decorated ZnO NWs. Characterization of the synthesized samples by different methods confirms the desired chemical composition, morphology, and phases. H-2 gas sensing studies reveals the highly sensitive and selective response of the optimized gas sensor to H-2 at 200(degrees)C. In the presence of H-2/CO and H-2/NO2 gas mixtures, the NiO-shelled Pd-decorated ZnO NW sensor displays good selectivity for H-2, but not the Pd-decorated ZnO NW gas one. The NiO-shelled Pd-decorated ZnO NW gas sensor efficiently detected H-2 also in the presence of 40% relative humidity and displays good stability even after 1 month. The present results can open the doors to the fabrication of highly selective H2 gas sensors using the described rationale design.