Ni-TiO2 nanotube arrays for highly sensitive and selective detection of acetone vapor

Abstract

To further improve the acetone sensing performance of TiO2 nanotube arrays synthesized by an electrochemical anodization method, the Ni dopants in lower variable valences than Ti4+ ions were introduced into TiO2 nanotube arrays via a hydrothermal method. At the prime operating temperature of 420 °C, the Ni-TiO2 nanotube arrays-based sensor showed almost three times higher acetone vapor response (29.5–100 ppm) than the TiO2 sensor, as well as a higher degree of linearity (R2 = 0.99) and sensitivity (slope = 1.03) to 1–500 ppm acetone, faster response/recovery speed (1.8/88.3 s), higher long term stability (29.5 ± 1.9 %), and better selectivity against toluene, alcohol, methoxythanol, methanol, DMF, glycol, hydrogen, and ammonia. As revealed by XRD, SEM, and XPS, the improved acetone sensing performance of Ni-TiO2 nanotube arrays should be contributed by the substitution of the smaller Ni2+/Ni3+ ions for the larger Ti4+ ions in TiO2 lattice which yielded the reduction of nanotube thickness and average crystallite size, as well as the increase in the content of OV on the surface.