Cu-doped SnO2/rGO nanocomposites for ultrasensitive H2S detection at low temperature

Hydrogen sulfide (H 2 S) detection remains a significant concern and the sensitivity, selectivity, and detection limit must be balanced at low temperatures. Herein, we utilized a facile solvothermal method to prepare Cu-doped SnO 2 /rGO nanocomposites that have emerged as promising candidate materials for H 2 S sensors. Characterization of the Cu-SnO 2 /rGO was carried out to determine its surface morphology, chemical composition, and crystal defects. The optimal sensor response for 10 ppm H 2 S was ~1415.7 at 120 °C, which was over 320 times higher than that seen for pristine SnO 2 CQDs ( R a / R g = 4.4) at 280 °C. Moreover, the sensor material exhibited excellent selectivity, a superior linear working range ( R 2 = 0.991, 1–150 ppm), a fast response time (31 s to 2 ppm), and ppb-level H 2 S detection ( R a / R g = 1.26 to 50 ppb) at 120 °C. In addition, the sensor maintained a high performance even at extremely high humidity (90%) and showed outstanding long-term stability. These superb H 2 S sensing properties were attributed to catalytic sensitization by the Cu dopant and a synergistic effect of the Cu-SnO 2 and rGO, which offered abundant active sites for O 2 and H 2 S absorption and accelerated the transfer of electrons/holes.