Large-Scale Synthesis of Hierarchically Porous ZnO Hollow Tubule for Fast Response to ppb-Level H₂S Gas

Abstract

Response and recovery time to toxic and inflammable hydrogen sulfide (H 2 S) gas are important indexes for metal oxide sensors in real-time environmental monitoring. However, large-scale production of ZnO-based sensing materials for fast response to ppb-level H 2 S has been rarely reported. In this work, hierarchically porous hexagonal ZnO hollow tubule was simply fabricated by zinc salt impregnation and subsequently calcination using absorbent cotton as the template. The influence of calcination temperature on the corresponding morphology and sensing properties is also explored. The hollow tubules calcined at 600 °C are constructed from abundant cross-linked nanoparticles (∼20 nm). Its Brunauer−Emmett−Teller surface area is 31 m 2 •g −1 and the meso-and macroporous sizes are centered at 35 and 115 nm, respectively. The sensor with a lower detection limit of 10 ppb exhibits a fast response speed of 29 s toward the 50 ppb H 2 S rather than those of the reported intrinsic and doped ZnO-based sensing materials. Furthermore, the sensor shows a wide linear range (10−1000 ppb), good reproducibility, and stability. Such excellent trace ppb-level H 2 S performances are mainly related to the inherent characteristics of hierarchically porous hollow tubular structure and the surface-adsorbed oxygen control type mechanism.

1D Metal Oxide Semiconductor Materials for Chemiresistive Gas Sensors: A Review

“…Ubiquitous in various industries and settings, gas sensors are devices that allow for detection of gaseous molecules, which have applications ranging from manufacturing process control to environmental monitoring and emission control, and especially for fire safety (i.e., smoke alarms) in everyday life. Gas sensors are designed and optimized to have performance criteria for specific applications, such as, the ability to detect low concentrations of certain gas analytes in the ppb levels, [ 1–7 ] to have short response time, [ 8–11 ] and low power consumption (i.e., low operation temperature). [ 12,13 ] With the advancement in nanotechnology, this has consequently enabled significant improvements in the field of gas sensors, especially via development of novel sensing nanomaterials for enhancement of sensor performance.…”

“…Furthermore, chemiresistive sensors based on MOS materials require simple and low‐cost synthesis and fabrication methods, while providing several avenues for controlling sensing properties via nanoengineering of MOS chemical, compositional, and structural properties. [ 34 ] Until now, both p‐type (e.g., CuO [ 3,46,47 ] ) and n‐type MOS (e.g., WO 3 , [ 7,48–50 ] ZnO, [ 4,51–54 ] SnO 2 , [ 11,16,23 ] TiO 2 , [ 56,57 ] In 2 O 3 [ 12,54,55 ] ) have been widely used as gas sensing materials due to their high sensing performance.…”

Importance of N-P-N Junction in H2S Sensing Process of SnO2-CuO Heterostructures: A Theoretical Macroscopic Approach

“…Longitudinal cross-sectional view with corresponding total electrical resistances in presence of H 2 S gas: (Up) Mono-wire model, (Down) Two-wires model. would make these systems less sensitive toward H 2 S gas comparing to the "two-wires" configuration according to (2). To gain a better insight toward this blocking effect, response of a solo CuO structure consists of a CuO tube and a CuO disk with exact geometries and positions of the CuO shell and CuO disk used for "two-wire" configuration, was also computed.…”

“…It can cause cracking and destruction of various equipment during drilling operations in oil and gas fields [1]. Semiconducting metal-oxides such as ZnO [2], NiO [3], WO 3 [4], Fe 2 O 3 [5] and SnO 2 [6]- [8] have been reportedly used for detection of this detrimental gas. Among these oxides, particular attentions have been paid to tin dioxide.…”

A highly sensitive ppb-level H2S gas sensor based on fluorophenoxy-substituted phthalocyanine cobalt/rGO hybrids at room temperature

“…The use of CuO, WO 3 , ZnO, SnO 2 , Fe 2 O 3 and other metal oxides has been reported to detect H 2 S at the ppm level. [7][8][9][10][11][12][13][14][15][16][17] The detection limit of most materials is very low, but the optimal working temperature (OWT) is still very high and the sensitivity is very low. For example, in 2016, the a-Fe 2 O 3 sensor prepared by Lin et al had a sensitivity of 11.7 for hydrogen sulde at 350 C and 100 ppm.…”