fig4

From: Recent advances in room-temperature hydrogen sulfide gas sensors: materials design, interface engineering, and sensing mechanisms

Figure 4. Performance of photoactivated-based H₂S sensors. Schematic illustration of the material preparation process (A); SEM images of pure SnO₂ (B) and CuO-SnO₂ (C) samples; real-time response (D), mean response (E) and response/recovery times (F) for 10 ppm H₂S under various visible-light activation. Figure 4 is reproduced from Ref.^[154], under CC BY 4.0 license. PVP: Polyvinylpyrrolidone; DMF: N,N-dimethylformamide; SEM: scanning electron microscope; R_a/R_g: resistance in air/resistance in test gas; ppm: parts-per-million.