Enhanced gas sensing property of Co3O4 matrix nanocomposites with halloysite nanotubes toward triethylamine

Despite their high surface reactivity, the gas sensor based on Co3O4 nanoparticles frequently suffers from a low response to volatile organic compounds (VOCs) due to high-temperature sintering and inefficient resistance modulation. Herein, halloysite nanotubes (HNTs) were incorporated as the additive into the Co3O4 nanoparticle matrix to enhance the sensing property toward VOCs in terms of gas response (Rg/Ra) and operation stability. Co3O4 nanoparticles intimately attached on HNTs were achieved by a facile deposition-precipitation method followed by calcination. The best-performing Co3O4/0.3HNTs-based sensor had a high gas response of 22.9 to 50 ppm triethylamine at 240 °C, which was 4.9 times than that of Co3O4 alone. The enhanced sensitivity could be attributed to the HNT incorporation that facilitated effective resistance modulation, surface property tuning, as well as surface defect formation. These results bring new insight into an enhancement of gas sensing property of a p-type metal oxide with insensitive materials. They also provide a potential to expand the application of aluminosilicate clays to gas sensors.