Ultrafast Response and High Selectivity toward Acetone Vapor Using Hierarchical Structured TiO₂ Nanosheets

Abstract

For the development of high-performance gas sensors, ultrafast response and high selectivity are critical requirements for many practical applications. An alternative strategy is to employ hierarchical nanostructured materials in gas sensors. In this work, we report newly synthesized TiO2 hexagonal nanosheets with a hierarchical porous structure, which demonstrate an ultrafast gas response and high selectivity toward acetone vapor for the first time. A simple one-step annealing process to prepare hierarchical TiO2 nanosheets derived from layered TiSe2 nanosheet templates is reported. The hierarchical structure interlaced with anatase TiO2 nanosheets showed an open porous characteristic. The average pore size was about 20 nm examined using a high-resolution TEM. The gas sensing properties toward acetone vapor of the novel hierarchical structured TiO2 nanosheets were characterized in detail including optimal operation temperature, sensitivity, selectivity, response/recovery time, and long-term stability. The gas sensing response and recovery times were 0.75 s and 0.5 s, respectively. We attribute these superior response properties to its unique hierarchical pore structure with a high specific surface area. The results show great potential for acetone vapor detection, particularly in dynamic ultrafast monitoring by using the synthesized hierarchical structured TiO2 nanosheets.

Ru-functionalized Ni-doped dual phases of α/γ-Fe2O3 nanosheets for an optimized acetone detection

“…In acetone atmosphere, adsorbed acetone is oxidized by ionosorbed oxygen, thus trapped electrons can be released back into the conducting valance to decrease the oxide resistance. These processes cause a resistance change according to its concentration, which is expressed below, as previously reported [43]: Ru/Ni-α/γ-Fe 2 O 3 superior sensing performances and high selectivity for acetone may be attributed to several factors, such as the unique nanosheet morphology, the coexistence of two phases, oxygen vacancies density, Ni doping, and the catalytic activity of Ru nanoparticles. The nanosheet morphology can maximize the surface area and edge, thus providing a large number of active sites for gas molecules absorption.…”

Rationally Designed TiO2 Nanostructures of Continuous Pore Network for Fast‐Responding and Highly Sensitive Acetone Sensor

“…To the best of the author's knowledge, the gas response of 299 is the highest compared to the previously reported TiO 2 ‐based CH 3 COCH 3 sensors as summarized in Table 1 . [ 39–46 ]…”

“…To the best of the author's knowledge, the gas response of 299 is the highest compared to the previously reported TiO 2 -based CH 3 COCH 3 sensors as summarized in Table 1. [39][40][41][42][43][44][45][46] To investigate the structural superiority of highly porous 3D TiO 2 over other TiO 2 nanostructures, the FEM simulation with a time-dependent gas diffusion model was conducted as shown in Figure 3a. Following our gas measurement system setup, gas molecules were assumed to be injected from the top of the nanostructures to the bottom.…”

“…In addition, finite element method (FEM) simulation with a time-dependent gas diffusion model was conducted to verify the effectiveness of our 3D TiO 2 for extremely high gas molecule accessibility under low (311 particle models) and high (1306 particle models) gas concentrations. As a result, 3D TiO 2 exhibited an extremely high gas response of 299 (dividing the changes in saturated resistance before and after exposure to CH 3 COCH 3 (R a and R g , respectively) by the resistance after the exposure (R g ), expressed as R a /R g −1) at the concentration of 50 ppm CH 3 COCH 3 , which is the highest compared to any previously reported TiO 2 -based gas sensors to the best of the author's knowledge, [39][40][41][42][43][44][45][46] and theoretical detection limit to CH 3 COCH 3 as low as 260 ppt with an extremely fast response time of less than 1 s. The effective utilization of the major electrical conduction path at the bottom of sensing materials through systematically designed MOS nanostructures and precisely controlled current path demonstrated in this study can provide a promising perspective toward the development and actual field application of MOS-based gas sensors for IoE purposes.…”

Ultrasensitive and low detection limit of acetone gas sensor based on ZnO/SnO2 thick films

“…Water is omnipresent and has vital effect on the sensing performance of metal oxide semiconductors, ensures continuous interest of surface scientists in the interaction of water with inorganic materials. [29][30][31][32][33][34] In the present study, we also investigated the effect relative humidity (RH) on the sensing performance. Fig.…”