Tailoring the triethylamine vapor sensing on Co-Fe bimetallic oxide nanosheets assemblies by crystal structure and doping sites

Abstract

Triethylamine monitoring plays a vital role in industrial safety and marine environmental protection. Co3O4 has been proved to be a promising sensitive material for triethylamine detection. Promoting gas reactions on the surface of sensitive materials is the key to realizing high-performance gas sensors. In this work, MgO microrods were used as sacrificial templates to prepare nanosheet-assembled hollow microtubular Co-Fe bimetallic oxides. The large specific surface area, small crystallite size, and stretched lattice of Co-Fe bimetallic oxides boosted surface gas reactions and improved the response to triethylamine vapor. The modulation in the energy band structure caused by doping-occupied sites of iron on the gas-sensing properties was also considered. The preferential occupation of tetrahedral sites by multivalent iron reduced the work function and band gap of the material, thus enhancing the formation of ion-adsorbed oxygen. In these cases, the sample with about 20 % iron content (CF2) showed the optimum triethylamine sensing performance at 195 °C, with a detection limit as low as 1 ppm, a gas response of 10.9 for 100 ppm triethylamine, and a 58 % shorter recovery time. In addition, it also exhibited excellent selectivity and repeatability. The gas adsorption model was additionally used to analyze the response and recovery process from an energy perspective. This work contributes insights into the sensitivity enhancement and response-recovery process modulation of spinel oxide gas sensors, mainly in terms of crystal structure and doping sites.