Hierarchical flower-like Cu-doped SnO2/Ag2S heterojunctions decorated with Ag for excellent sensing performance toward n-butanol at low operating temperatures

Abstract

The design of materials for the detection of n-butanol at low operating temperatures is of great significance for the reduction of power consumption and the improvement of the safety of the gas sensor. In this study, the solvothermal method and subsequent Ag-loading treatment were employed to synthesise hierarchical flower-like Cu-doped SnO₂/Ag₂S heterojunctions decorated with Ag (CSAA). The morphological and structural characterisation demonstrated that the amount of Cu^2 + doping and the duration of electroless Ag plating played a pivotal role in the morphological evolution of the SnO₂-based hierarchical structure. The optimal CSAA composite exhibits the highest response of 1136 and the shortest response time of 6 s to 50 ppm n-butanol at 80°C, accompanied by superior selectivity, repeatability, humidity and long-term stability. The enhanced sensing performances of the CSAA sensor can be mainly ascribed to the hierarchical porous structure, the doping of Cu²⁺, the construction of SnO₂/Ag₂S heterostructures and the decoration of Ag nanoparticles (Ag NPs). Furthermore, the density functional theory simulation was employed to investigate the influence of Ag NPs and Ag₂S on the adsorption properties and electronic behaviour of n-butanol on the surface of SnO₂. This work proposes a friendly strategy and theoretical support for enhancing the sensing performance of MOS sensors in the practical detection of n-butanol.