fig6

Figure 6. (A) Sensing responses of the Ce-X/mWO₃ sensor to 50 ppm H₂S at various temperatures (A₁); Sensing mechanism of Ce-X/mWO₃-based gas sensors for H₂S detection (A₂). Energy band structure and electron-transfer process of Ce-X/mWO₃ sensitive material exposure in air and H₂S-air mixture (A₃). Figure 6A is quoted with permission from Liu et al.^[127];( B) Gas responses of pure In₂O₃ (B₁) and 11.7 Ce-In₂O₃ (B₂) hollow spheres exposed to 20 ppm acetone (Ace), CO (C), ammonia (A), H₂ (H), and toluene (T) at 450 °C in dry and humidity (r.h. 80%); Polar plots of gas responses of pure In₂O₃ (B₃)and 11.7 Ce-In₂O₃ (B₄) hollow spheres exposed to various reducing gases in dry (red) and r.h. 80% (blue). C: Self-refreshing of the In₂O₃ sensing surface by the CeO₂ nanoclusters. Water vapor inflow (C₁), chemisorption (C₂), desorption (C₃), and oxygen ion regeneration (C₄). Figure 6B and C is quoted with permission from Yoon et al.^[132]. ppm: Parts-per-million.