fig4

Figure 4. (A) Schematic illustration of SnO₂ nanorods functionalized with Au-CuO composite nanocatalyst via GLAD, along with the corresponding cross-sectional and top-view scanning electron microscopy (SEM) images. Sensitivity of 1 nm-deposited sensor array to six gases (10 ppm acetone, toluene, xylene, ethanol, ammonia, H₂S) at 300 °C. Reprinted with permission. Copyright 2024^[133], Springer Nature; (B) Schematic and SEM images of oxygen vacancy-rich SnO₂ nanosheets. Dynamic response-recovery curves of SnO₂ nanosheets after nitrogen plasma treatment for 2.5 min upon exposure to 0.5-50 ppb NO₂ at 80 °C. Reprinted with permission. Copyright 2025^[135], American Chemical Society (ACS); (C) Schematic and a cross-sectional SEM image of W-decorated NiO nanoigloos with a bar graph showing the response of bare and W-decorated NiO nanoigloos to various target gases at 300 °C. Reprinted with permission. Copyright 2019^[137], American Chemical Society (ACS); (D) Schematic and SEM image of Au-decorated Sn₃O₄ nanoflowers with response values of Sn₃O₄ sensors at 190 °C and Au/Sn₃O₄ sensors at 160 °C to 5 ppm acetone and interfering biomarker gases. Reprinted with permission. Copyright 2024^[139], American Chemical Society (ACS); (E) Schematic of NO₂ sensing on the oxygen-adsorbed and hydroxide-functionalized SnO₂ surface. Response curves to 1-5 ppm NO₂ in dry and RH 20% conditions. Reprinted with permission. Copyright 2019^[7], Wiley; (F) Cross-sectional SEM image and gas-sensing performance of the 0.4CeO₂/Rh-SnO₂ sensor, along with dynamic response transients to 0.1-1 ppm benzene, toluene, ethylbenzene, xylenes, styrene (BTEXS) at 300 °C. Reprinted with permission. Copyright 2023^[149], Springer Nature. GLAD: Glancing angle deposition.