Surface tuning of halloysite nanotubes with Fe₃O₄ and 3-D MnO₂ nanoflakes for highly selective and sensitive acetone gas sensing

Nanosized M-HNTs-MnO₂ (Magnetic halloysite nanotubes-manganese dioxide) nanocomposite was synthesized by the reduction-precipitation method followed by the hydrothermal process. The existence of MnO₂ nanoflakes on M-HNTs represents 3-D nanostructures without stacking of nanotubes and agglomeration. The sensor-based on M-HNTs-MnO₂ nanocomposites exhibits higher sensor response (R_air/R_gas = 35.6) to 100 ppm of acetone gas at operating temperature (150 °C), with a short response-recovery time (3 s/7 s). The M-HNTs-MnO₂ nanocomposite sensor shows excellent potential to act as a low cost, low-temperature sensor for acetone gas, with high acetone selectivity under high humidity conditions and with the interference of other gases. The high surface to volume ratio, three-dimensional nanostructure, and strong interactions between M-HNTs and MnO₂ nanoflakes are accountable for the improvement of acetone sensing performance. Based on the high acetone selectivity, high stability and fast dynamic response, the M-HNTs and MnO₂ sensor is an extremely appropriate candidate for a low-cost acetone sensor, and the projected approach offers a way to develop gas sensors that can be function at low temperatures for a wide variety of applications.