Biotemplate-directed synthesis of Cr2O3 mesoporous monotubes for enhanced sensing to trace H2S gas

Herein, Cr2O3 nanomaterials with high sensing towards trace H2S at low energy consumption were controllably synthesized by simple chromium nitrate solution immersion and air calcination using waste willow catkins as bio-template. Amongst, Cr-400 hierarchical structure obtained from the calcination of 400 °C exhibits monotube morphology assembled by well-crystalline nanoparticles, and it has uniform mesoporous distribution and large specific surface area. This structure features help to the fast accessibility of gas molecules and provide an effective platform for surface adsorption and chemical reaction, which dramatically enhances the detection ability of Cr2O3-based sensor to trace H2S gas for the first time. At low operating temperature of 133 °C, Cr-400 sensor exhibits high response value (S = 24.4) to 50 ppm H2S gas and low actual detection limit (100 ppb). Simultaneously, it also has good comprehensive gas-sensing performance involving reversible response-recovery, high selectivity, satisfactory stability and moisture resistance. In addition, we also discussed the enhanced gas-sensing mechanism in details.