Au@Cu₂O core–shell nanoparticles (NPs) were synthesized by a solution method at room temperature and applied for gas sensor applications. Transmission electron microscopy (TEM) images showed the formation of Au@Cu₂O core–shell NPs, where 12–15 nm Au NPs were covered with 60–30 nm Cu₂O shell layers. The surface plasmon resonance (SPR) peak of Au NPs was red-shifted (520–598 nm) after Cu₂O shell formation. The response of Au@Cu₂O core–shell NPs was higher than that of bare Cu₂O NPs to CO at different temperatures and concentrations. Similarly, the response of Au@Cu₂O core–shell NPs was higher than that of bare Cu₂O NPs for NO₂ gas at low temperature. The improved performance of Au@Cu₂O core–shell NPs was attributed to the pronounced electronic sensitization, high thermal stability and low screening effect of Au NPs.

PdAu_alloy@ZnO CSNPs are prepared and evaluated for hydrogen detection with superior behavior with respect to pure ZnO. Improvement is attributed to .synergistically catalytic effects between Pd, Au and ZnO in PdAu_alloy@ZnO core–shell sensory system

The sensitivity/selectivity of Au@In ₂ O ₃ core–shell hybrid heteronanostructures is boosted by the insertion of Au NPs.

P–n heterojunction nanostructures (NSs) are emerging as a promising class of hybrid materials for gas-sensing applications. In this work, we report a facile, cost-effective synthesis technique to fabricate unique, hybrid PdO@ZnO p–n heterojunction NSs as high response and selective acetaldehyde gas sensors. Initially, Pd@ZnO core–shell NSs (CSNSs) were synthesized, and subsequently transformed into hybrid PdO@ZnO p–n heterojunction NSs by a simple high-temperature calcination method. The morphological study of the prepared hybrid NSs was carried out by transmission electron microscopy (TEM), which revealed that 10 ± 5 nm sized Pd nanoparticles (Pd NPs) were encapsulated in the center of the ZnO shell of 40–50 nm to form approximately 75–135 nm sized Pd@ZnO CSNSs. The more crystalline, flower-shaped PdO@ZnO p–n heterojunction NSs were formed after the Pd@ZnO CSNSs were calcined at 500 °C for 2 h. When employed as a gas sensor, the hybrid PdO@ZnO p–n heterojunction NSs demonstrated high sensitivity and selectivity to acetaldehyde gas amongst other gases (ethanol, CO, H₂, and CH₄). The PdO@ZnO p–n heterojunction NSs-based sensor delivered the highest response (R_a/R_g = 76) to 100 ppm acetaldehyde at 350 °C, as compared to the pristine ZnO NSs sensor (R_a/R_g = 18). The improved sensing performance of the hybrid PdO@ZnO p–n heterojunction NSs-based sensor over the pristine ZnO NSs-based sensor was attributed to the combination of the resulting synergistic effect due to the formation of the p–n heterojunction between PdO and ZnO NPs, the catalytic dissociation effect of PdO, and the high surface area of the PdO@ZnO p–n heterojunction NSs.

Plasmonically driven photocatalytic hydrogen evolution activity of a Pt-functionalized Au@CeO₂ core–shell catalyst under visible light was insightfully investigated for the first time.