Highly sensitive formic acid detection at low temperatures using Co-doped CuO cocklebur-like nanostructures

Formic acid, a corrosive and toxic organic compound, poses risks to health and ecosystems due to environmental residues, highlighting the need for efficient detection methods. This study synthesized pure CuO and Co-doped CuO (CCO) cocklebur-like nanostructures using a one-step hydrothermal method. Moreover, the crystal structure, morphology, and elemental composition of CCO-4 samples were also investigated. Experimental results demonstrated that the optimal sample, CCO-4, exhibited a gas sensing response value of 118.6–100 ppm formic acid at an operating temperature of 125°C, which is approximately 16.5 times higher than that of pure CuO. Additionally, CCO-4 displayed excellent comprehensive performance, including low power consumption, a detection limit as low as 100 ppb, good selectivity for formic acid, and long-term stability. Based on Lewis acid-base theory and the formation of Cu 2 + −O 2 -• metal ion complexes, the gas sensing process and sensitization mechanism of CCO-4 were systematically analyzed. These findings offer new theoretical and technical pathways for developing low-power, high-performance formic acid sensors.