Research paper
Hybridization of ZnSnO3 and rGO for improvement of formaldehyde sensing properties

https://doi.org/10.1016/j.snb.2017.10.015Get rights and content

Highlights

  • rGO/ZnSnO3 nanocomposites were synthesized by solution-based self-assembly process.

  • The 3 wt% rGO/ZnSnO3 shows high sensitivity, good selectivity and rapid response-recovery.

  • The mechanism of enhancing sensing is ascribed to large surface and formation of heterojunction.

Abstract

The rGO/ZnSnO3 composites have been elaborately synthesized by a facile solution-based self-assembly synthesis method at low temperature. The structure, morphology, thermal stability, composition and specific surface area of composite were characterized by XRD, SEM, TG, XPS and BET analysis, respectively. The sensing experiments show that the sensor based on 3 wt% rGO composite not only exhibits high sensitivity (low limit of detection), excellent selectivity and linearity relationship between responses and formaldehyde concentration from 1 to 10 ppm, but also exhibits fast response and recovery at operating temperature of 103 °C. The enhanced sensing mechanism of the hybrid to formaldehyde was discussed in detail, which can mainly be ascribed to the large specific surface area for gas adsorption, porous channels for gas diffusion, the fast carrier transport benefited from rGO and the formation of heterojunction at the interface between the rGO and ZnSnO3.

Graphical abstract

The rGO/ZnSnO3 composite have been synthesized by a modified Hummers method and a facile solution-based self-assembly synthesis method at low temperature. It shows good formaldehyde sensing performance which is ascribed to the large surface area, a mass of active sites and the formation of heterojunction in the interface between rGO and ZnSnO3.

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Introduction

The most concerned is formaldehyde among VOCs due to its carcinogenicity according to the World Health Organization (WHO), and it is the main pollutant after home decoration [1]. If the persons repeated or long-term exposure to formaldehyde will result in headaches, eye and airway discomfort even at levels below the odor threshold (odor threshold is 0.5–1.0 ppm) [2]. The hierarchical ZnSnO3 nanostructures possesses high specific surface area, environmental compatibility, flame retardation, low-cost fabrication and good gas sensing properties, which has attracted considerable attention as a multifunctional material, but the high operating temperature(>200 °C), low sensitivity and poor selectively restrict the application of ZnSnO3 in sensor field [3], [4], [5], [6]. As a rising star of carbon family, reduced graphene oxide (rGO) sheets with a one-atom-thick planar sheet comprising an sp2-bonded carbon structure, attract great research interest in various fields due to its intriguing properties of flexibility, good conductivity, superior chemical stability, large surface-to-volume ratio. In recent years, increasing interest has been aimed toward the incorporation of graphene in inorganic or organic materials, which is an effective method to obtain a promising material for detection of VOCs [7], [8], [9], [10]. Such as Xian et al. synthesized rGO/ZnO hybrid films hydrothermal followed by layer-by-layer self-assembled methods for room temperature formaldehyde detection [8]; Zhang et. al synthesized rGO/Ag nanoparticle composite film via electrostatic self–assembly followed by UV reduction to detect trace formaldehyde [10];An et. al synthesized WO3 nanorods/graphene nanocomposites through hydrothermal method and show excellent performance to NO2 gas sensing [11]. Inspired by these, in our work the ZnSnO3 hierarchical microspheres were anchored on rGO sheets by solution-based self-assembly process to obtain a new sensing material for detection of formaldehyde, which not only overcomes restacking and aggregation among rGO sheets due to strong van der Waals interaction between their hydrophobic basal planes, but also exhibits higher sensing performances than their constituent counterparts. For comparison, the sensing properties of the materials to formaldehyde reported in literatures and in this work are listed in Table 1 [8], [9], [12], [13], [14], [15].

Section snippets

Synthesis of graphene oxide (GO)

The graphite oxide (GO) was prepared by a modified Hummers method [16]. Under the condition of ice water bath, 0.5 g graphite and 0.74 g NaNO3 (Xilong chemical company, >99.0%) were added into 34 mL concentrated H2SO4 (Beijing chemical company, >99%). 5 g KMnO4 (Beijing chemical company, 98.0%) was slowly added into the stirring solution while keep the temperature of mixed solution below 20 °C. After vigorous stirring at 35 °C for 2 h, the solution was then cooled to room temperature. 250 mL deionized

Structural and morphology of materials

The micromorphology and microstructures of rGO/ZnSnO3 were observed by SEM, HRTEM and XRD images as shown in Fig. 2. Without any auxiliary additives in the synthesis process, the morphology of ZnSnO3 is governed by the intrinsic crystal structures and chemical potential to form microcubes [18]. When add CTAB and NH3 in step 2 of Fig. 1, the morphology of ZnSnO3 was controlled by the external added surfactant and ammonia to form ZnSnO3 hierarchical microspheres and anchored on rGO. Fig. 2(b, c

Conclusions

In conclusion, the 3 wt% rGO/ZnSnO3 composite was synthesized by a facile, mild conditions, cost effectiveness self-assembly method at low temperature and fabricated to a sensor for detection of HCHO. The composite shows outstanding sensing performance to HCHO, which not only exhibits high response (12.8–10 ppm HCHO), low detection limit (0.1 ppm of HCHO) and excellent anti-interference, but also exhibits linearity relationship between responses and gas concentration (R = 0.994) All the good sensing

Acknowledgments

This work was supported by the National Natural Science Foundation of China (Grant Nos. 51372013 and 51772015), Beijing Engineering Center for Hierarchical Catalysts, the National Key R&D Program of China (2016YFC0207100) and Foundation of Guangxi Department of Education(2017KY0025).

Jianhua Sun received his MS degree from Guangxi University, and is currently pursuing PhD degree in Chemistry at BUCT. His research is focused on the development of gas sensing materials.

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  • Cited by (0)

    Jianhua Sun received his MS degree from Guangxi University, and is currently pursuing PhD degree in Chemistry at BUCT. His research is focused on the development of gas sensing materials.

    Shouli Bai received MS degree in physical chemistry from Chinese Academy of Science in 1990. His research interests include catalytic and sensing materials as well as their application in chemical sensors and solar cell based on dye-sensitized. He is a professor in Science College at Beijing University of Chemical Technology (BUCT). He awarded a First Class National and Beijing Education Prize at 2008 and 2009, respectively.

    Ye Tian received her BS and MS degree from Beijing University of Chemical Technology, and is currently pursuing PhD degree at Beijing University of Chemical Technology.

    Yanhong Zhao received her BS degree from Beijing University of Chemical Technology in 2014, and received her MS degree from Beijing University of Chemical Technology in 2017.

    Nin Han got his Ph. D. degree in Chemical Engineering from Institute of Process Engineering in 2010. He was a postdoctor in Department of Physics and Materials Science in City University of Hong Kong in 2010–2014, and is now a professor in Institute of Process Engineering since 2014. His research interest includes preparation of metal oxide semiconductors and III–V compound semiconductors, and applications in gas sensors, electronics and optoelectronics.

    Ruixian Luo was a Research Associate in the Department of Chemical Engineering at Purdue University in 1985–1987 and worked as a visiting professor in Case Western Reserve University (CWRU) in 1994–1998. Her research interests are sensing materials and chemical sensors. She is now pursuing academic research and guiding graduate students at BUCT.

    Dianqing Li received MS degree from BUCT and PhD from Tianjin University in 1989 and 2001, respectively. He is a professor of State key Laboratory of Chemical Resource Engineering at BUCT. His main research interests are development and application of functional inorganic materials. He has successfully completed many applied projects and awarded a National Technology Invention Prize of Second Class at 2010 and a Science and Technology Prize of First Class by Beijing Municipality.

    Aifan Chen was a Visiting Professor at Purdue University and CaseWestern Reserve University in 1986–1988. His research interests are in catalysis and sensors. He is currently a Professor at College of Science of BUCT.

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