Simple synthesis of Cu/Cu2O/CuO composites with dual adsorption capacity for conductometric NO2 detection

Starting from improving the sensing performance of sensing materials to NO2, it is still a challenge to synthesize a material that can simultaneously enhance the adsorption capacity of NO2 and the surface adsorbed oxygen content. In this paper, nano-sized octahedral HKUST-1 precursor was prepared by one-step hydrothermal method. After subsequent sintering treatment at different temperatures, a series of CuO-based composites with oxygen vacancies and pores were obtained. Among them, Cu/Cu2O/CuO composite shows the best response for 1 ppm NO2 at 50 °C (S =14.4), and excellent selectivity, moisture resistance and reproducibility. The minimum detection limit is as low as 50 ppb. In addition, XPS, PL, NO2-TPD analyses and DFT calculations were used to study the reasons in detail for the excellent NO2 gas sensing performance of Cu/Cu2O/CuO. The presence of Cu in the composite improves the ability of material to adsorb NO2, while the presence of Cu2O and oxygen vacancies make the material have more surface adsorbed oxygen. The combined effect of the two makes the material have good NO2 gas sensing performance. The synthesis of this composite material provides new ideas for improving the detection ability of toxic and harmful gases.