Improved BTEX gas sensing characteristics of thermally treated TiO2 hierarchical spheres manifested by high-energy {001} crystal facets

被引：26

作者：

Tshabalala, Zamaswazi P. ^{[1
,2
,3
]}

Mokoena, Teboho P. ^{[1
,2
]}

Hillie, Kenneth T. ^{[1
,2
]}

Swart, Hendrik C. ^{[2
]}

Motaung, David E. ^{[2
,3
]}

机构：

[1] CSIR, DSI, Ctr Nanostruct & Adv Mat, ZA-0001 Pretoria, South Africa

[2] Univ Free State, Dept Phys, POB 339, ZA-9300 Bloemfontein, South Africa

[3] Univ Limpopo, Dept Phys, Private Bag X1106, ZA-0727 Sovenga, South Africa

来源：

SENSORS AND ACTUATORS B-CHEMICAL | 2021年 / 338卷

基金：

新加坡国家研究基金会;

关键词：

TiO2 hierarchical spheres; Annealing; BTEX; Gas sensing; SELECTIVE DETECTION; SENSITIVE DETECTION; ANATASE TIO2; TOLUENE; SENSORS; SURFACE; XYLENE; NANOSHEETS; NANOWIRES; NANORODS;

D O I：

10.1016/j.snb.2021.129774

中图分类号：

O65 [分析化学];

学科分类号：

070302 ; 081704 ;

摘要：

Aromatic hydrocarbons like benzene, toluene, ethylbenzene and xylene (BTEX) are lethal volatile organic compounds, which should be precisely monitored to maintain occupational safety and indoor air quality. Thus, herein, the superior sensitivity towards toluene and ethylbenzene, among other BTEX vapours was exhibited by thermally treated sea-urchin like TiO2 hierarchical spheres achieved via hydrothermal method. X-Ray diffraction patterns displayed an improvement in crystallinity with annealing temperature and a total phase transformation to rutile phase, due to thermal instability of anatase phase. The Brunauer-Emmett-Teller surface area analyzer showed that the pore diameter increased with annealing temperature, whereas a thermal quench after 500 degrees C was observed on the photoluminescence results. To demonstrate the uniqueness of hierarchical structure and the effect of annealing at different temperatures, the gas sensing performances towards BTEX vapours was evaluated at various conditions. The sensor annealed at 500 degrees C (T5) displayed temperature-dependent selectivity towards ethylbenzene at 75 degrees C, with a detection limit of similar to 0.1 ppm (i.e. 100 ppb). The sensor annealed at 700 degrees C (T7) revealed the highest response of 13 towards toluene at 150 degrees C, due to exposed high surface energy {001} facets, containing plentiful active oxygen species, which are more active for adsorption of toluene. The T7 sensor demonstrated a clear stability towards toluene for about 90 days, displaying only minimal drift. The fundamental gas sensing mechanism associated to the detection of BTEX vapour was discussed in detail.

引用

页数：16