Rational design of CuO/In2O3 heterostructures with flower-like structures for low temperature detection of formaldehyde

Rational design of metal oxide heterostructures is of great importance for gas sensors to be applicable in the detection of inflammable, explosive and toxic gases. Herein, we designed CuO/In2O3 heterostructures with flower-like structures via a highly efficient one-step hydrothermal technique and constructed optimal structures to improve formaldehyde sensing properties. Consequently, the obtained 7-CuO/In2O3 flower-like structures with uniform p-n heterostructure and a large quantity of oxygen vacancies exhibits the best sensing properties for detecting formaldehyde. The corresponding response value is 11.67–10 ppm formaldehyde at a low operating temperature of 100 °C, which is approximately 2.97 times higher than that of pure In2O3 sensor (3.93 at 200 °C). Besides, the 7-CuO/In2O3 sensor also exhibits good reproducibility and stability, sub-ppm-level detection limit (1.38–0.5 ppm), high selectivity, and outstanding long-term stability, which benefits from the synergistic effect of strong oxygen adsorption capacity, p-n heterojunction between CuO and In2O3, catalytic effect of CuO, and the unique flower-like structures, showing the great potential for practical formaldehyde detection.