Gas-sensing properties of sensors based on single-crystalline SnO2 nanorods prepared by a simple molten-salt method

doi:10.1016/j.snb.2005.11.022

Sensors and Actuators B: Chemical

Volume 117, Issue 1, 12 September 2006, Pages 183-187

https://doi.org/10.1016/j.snb.2005.11.022 Get rights and content

Abstract

Sensors were fabricated by using single-crystalline SnO₂ nanorods prepared by a molten-salt method and their gas-sensing properties were investigated. It was found that the gas-sensing properties were dependent on the preparing conditions. The sensor based on the SnO₂ nanorods prepared with NP10 as a surfactant (sensor B) showed better performance than that with NP5 as a surfactant (sensor A). The two type sensors showed high response to volatile gases containing N or O atoms while showed low response to other volatile gases. The sensors showed good gas-sensing characters such as short response and recovery time, and a low detection limit. Especially, the response of sensor B to 1 ppm triethylamine attained 3.0 when operating at 350 °C.

Introduction

As a traditional semiconductor metal oxide, tin oxide is widely used to monitor toxic and inflammable gases in industry, gas-leak alarms and air pollution monitoring systems. Most of them are based on SnO₂ in a polycrystalline micro-meter form before the nanostructure tin oxide had been prepared. There are some critical difficulties to overcome for devices based on polycrystalline micro-meter materials, for example, limited maximum sensitivity, long response and recovery time because the gas-sensing properties of the materials were strongly influenced by the surface state and morphology of the materials [1].

One-dimensional (1D) nanostructure materials stand out as strong candidates for use as gas-sensing materials due to their enhanced surface-to-volume ratio. In the past years, SnO₂ nanowires, nanobelts, nanorods, nanowhiskers and nanotubes have been prepared by various kinds of methods such as thermal evaporation [2], [3], thermal decomposition [4], molten-salt synthesis [5], laser-ablation synthesis [6], sonochemical synthesis [7], aqueous growth [8], hydrothermal [9] and so on. On the other hand, gas sensors based on 1D nanostructure SnO₂ [10], [11], [12], [13] have been reported to show good sensitive properties such as low detection limit, good selectivity, short response time and recovery time. Different methods and conditions in synthesizing process would produce 1D nanostructure materials with different surface state and morphology, so it is very important to study the gas-sensing properties of the 1D nanostructure materials prepared by different methods under different conditions. Although SnO₂ nanorods prepared by molten-salt method have been reported [5], [14] their gas sensing properties have not been investigated up to now. In this letter, a molten-salt synthesis method was used to prepare single-crystalline SnO₂ nanorods under different conditions. Gas sensors based on the as-prepared sample were fabricated and their gas-sensing properties were investigated.

Section snippets

Experimental

The SnO₂ nanorod samples were prepared by a molten-salt method that was similar to that reported in reference [5]. In a typical experiment, 0.5 g SnO₂ powder as a starting material was mixed with 1.5 g NaCl and 5 ml surfactant (NP4, NP5, NP6, NP9 or NP10) in an agate mortar and then the mixture was ground for 30 min. NP4, NP5, NP6, NP9 and NP10 are a kind of nonionic surfactant whose molecular formula is shown in Scheme 1. When n = 4, 5, 6, 9 and 10, it represents NP 4, 5, 6, 9 and 10, respectively.

Results and discussion

In our experiments, NP4, NP5, NP6, NP9 and NP10 were used. Conversion from SnO₂ powder into SnO₂ nanorods was a morphology changing process. The results showed that the nanorods were obtained only under using NP5 (1), NP9 (2) and NP10 (3) as a surfactant. The process using NP10 as a surfactant showed the best result that almost all the product was nanorods when observed by TEM, while only a part of powder changed to nanorods when NP9 was used. The conversion ratio of the processes followed the

Conclusions

In summary, the sensors based on the single-crystalline SnO₂ nanorods prepared by a molten-salt method were fabricated and the gas sensing properties were investigated. The results demonstrated that sensor B based on the nanorods prepared with surfactant NP10 showed good sensing properties to volatile gases containing N or O atoms, such as short response and recovery time, low detection limit and so on. Especially, the response of sensor B to 1 ppm triethylamine attained 3.0 when operating at 350

Dan Wang is a PhD student of Sun Yat-sen University. His past work was about the organic light emitting diode now his research interests are mainly on new materials for gas sensor using.

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Dan Wang is a PhD student of Sun Yat-sen University. His past work was about the organic light emitting diode now his research interests are mainly on new materials for gas sensor using.

Xiangfeng Chu received his PhD from University of Science and Technology of China in 1999. He has been au associate professor in School of Chem. & Chem. Eng., Sun Yat-Sun University since 2002. His research field is inorganic functional materials.

Menglian Gong received his master degree from Sun Yat-sen University in 1982. He has worked in University of Pennsylvania from 1989 to 1991 as a visiting scholar, mainly on research of luminescence and laser spectrum. Currently, he is a professor of Sun Yat-sen University, and his research interest include porous silicon luminescence material, nanomaterials, inorganic functional materials and organic light emitting materials.

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Gas-sensing properties of sensors based on single-crystalline SnO2 nanorods prepared by a simple molten-salt method

Abstract

Introduction

Section snippets

Experimental

Results and discussion

Conclusions

Scripta Mater.

Basic aspects and challenges of semiconductor gas sensors

MRS Bull.

Nanobelts of semiconducting oxides

Science

Tin oxide nanowires, nanoribbons, and nanotubes

J. Phys. Chem. B

Preparation of SnO2 nanorods by annealing SnO2 powder in NaCl flux

J. Mater. Chem.

Laser ablation synthesis and electron transport studies of tin oxide nanowires

Adv. Mater.

Sonochemical synthesis of SnO2 nanobelt/CdS nanoparticle core/shell heterostructures

Chem. Commun.

Highly ordered SnO2 nanorod arrays from controlled aqueous growth

Angew. Chem. Int. Ed.

Gas-sensing properties of sensors based on single-crystalline SnO₂ nanorods prepared by a simple molten-salt method

Preparation of SnO₂ nanorods by annealing SnO₂ powder in NaCl flux

Sonochemical synthesis of SnO₂ nanobelt/CdS nanoparticle core/shell heterostructures

Highly ordered SnO₂ nanorod arrays from controlled aqueous growth