Ultrasensitive and ultra-selective room-temperature H2S gas sensor based on CuO-loaded In2O3 2D porous nanosheets

Abstract

Developing a cost-effective sensing material capable of detecting H₂S with ultra-sensitivity, ultra-selectivity, and low detection limits at room temperature remains highly anticipated. In this paper, two-dimensional (2D) porous In₂O₃ nanosheets were prepared by a simple solvothermal method, and then CuO was modified on the In₂O₃ surface by impregnation. The CuO/In₂O₃ two-dimensional porous structure allows the fabricated sensor to be highly sensitive to H₂S at room temperature. Modifying CuO on In₂O₃ significantly improves the response (R_a/R_g) to 10 ppm H₂S from 26 to 58000 at room temperature, while the response to other interfering gases (even 10 times the concentration of H₂S) not exceeding 5. After loading CuO, the response time was shortened from 56 s to 2 s, and the detection limit was reduced from 500 ppb to 50 ppb. Meanwhile, CuO/In₂O₃ also has good repeatability and long-term stability, and full recovery can be achieved by pulse heating. The gas sensing and characterization results demonstrate that the excellent sensing performance of CuO/In₂O₃ for H₂S at room temperature is due to the specific porous nanosheets morphology and structure of the material, the strong chemical affinity of alkaline CuO for H₂S, as well as the formation of p-n heterojunctions.