Low-Temperature-Enhanced and Ultrasensitive Exhaled H₂S Gas Sensor Based on Cu₂O-CuFe₂O₄ Nanoarrays

In this study, employing a 2D electrodeposition in situ assembly method, a high-performance H₂S sensor based on a p-n type Cu₂O-CuFe₂O₄ heterostructure ordered nanowire arrays was successfully fabricated on silicon substrates. Compared to Cu₂O, Cu₂O-CuFe₂O₄ nanowire arrays exhibits an ideal interfacial barrier structure and higher initial resistance, with a response to 10 ppm of H₂S at room temperature (20 ± 3 °C) increased by 225 times and a response time reduced by over 2400 s. The sensor demonstrates exceptional sensitivity (LOD = 10 ppb; response = 234.5), selectivity, and humidity resistance (stable response ∼6000 to 10 ppm of H₂S at 60-90% RH). Notably, it shows unique low-temperature-enhanced sensing, with a response of 8.365 × 10⁴ to 10 ppm of H₂S at -10 °C (vs 1.144 × 10⁴ at 20 °C). The sensor was successfully applied to detect H₂S in human oral exhaled breath, demonstrating its potential for noninvasive disease diagnosis and offering a promising approach for developing room-temperature breath analysis sensors.