NiO-CuO hydrangeas-like composite derived from Ni/Cu bimetallic MOFs for sensitive detection of H2S at room temperature

Highly sensitive and selective detection of trace-level concentration H2S remains a major challenge for metal oxide semiconductor gas sensor due to sulfuration-induced poisoning. Herein, a strategy to adjust the reaction site by constructing heterojunction with mixed-metal oxide is proposed. In this work, NiO-CuO hydrangeas-like composite is prepared by a solvothermal reaction and subsequent pyrolysis of bimetallic Ni-Cu-BTC in air. The characterization demonstrates that NiO-CuO hydrangeas has a large specific surface area (27.85 m2/g) and porosity (0.14 m3/g), which can provide abundant adsorption sites and diffusion pathways for gas molecules. Moreover, the sensing test results indicate that NiO-CuO sensors exhibit recoverable characteristic and superior sensing performance. The response value of 2NiO-CuO sensor to 1 ppm H2S in dry air at room temperature (25℃) is 3.99, which can be improved to 10.77 in 40 % humidity condition, making it suitable for practical application. Particularly, the sensor has a low detection limit of 50 ppb, a wide linear detection range (50 ppb-2 ppm), good repeatability, selectivity and long-term stability. The improvement of gas sensing response can be attributed to the porous structure, multiple p-p heterojunctions and synergistic effects between NiO and CuO.