Elsevier

Science Bulletin

Volume 60, Issue 15, August 2015, Pages 1348-1354
Science Bulletin

Article
Materials Science
Controlling synthesis and gas-sensing properties of ordered mesoporous In2O3-reduced graphene oxide (rGO) nanocomposite

https://doi.org/10.1007/s11434-015-0852-6Get rights and content

Abstract

Herein, we describe a strategy for fabricating ordered mesoporous In2O3-reduced graphene oxide (rGO) nanocomposite through ultrasonic mixing, where ordered mesoporous In2O3 nanoparticles are synthesized via the nanocasting route by using mesoporous silica as a hard template, which possess ordered mesostructure with a large surface area of 81 m2 g−1, and rGO nanosheets are synthesized from graphite via graphene oxide (GO) as intermediate. After coupled with rGO, mesoporous In2O3 could maintain its ordered mesostructure. We subsequently investigate the gas-sensing properties of all the In2O3 specimens with or without rGO for different gases. The results exhibit the ordered mesoporous In2O3-rGO nanocomposite possesses significantly enhanced response to ethanol even at low concentration levels, superior over pure mesoporous In2O3 nanoparticles. Similar strategy could be extended to other ordered mesoporous metal oxide–rGO nanocomposite for improving the gas-sensing property.

Introduction

There is an increasing concern on semiconducting metal oxide gas sensors in past decades regarding the awareness of environmental protection and human health. Various nanostructured metal oxides with high surface area have widely investigated as sensing materials 1., 2., 3., 4., 5.. Among them, ordered mesoporous metal oxides have attracted considerable attention since their accessible pores benefit not only the diffusion of gas molecules for increasing response rate, but also the reduction in aggregation and sintering for enhancing their thermal stability under high temperature during the fabrication and work process of gas sensor 6., 7., 8., 9., 10., 11., 12., 13.. For example, Tiemann and co-workers [13] reported the improved sensitivity of mesoporous In2O3 to CH4. Mao et al. [14] also reported the enhanced sensitivity of hierarchically mesoporous hematite microsphere toward formaldehyde (HCHO). Lai et al. [15] presented a low-cost synthesis of mesoporous In2O3 with tunable pore wall thickness by directly using solvent-extracted mesoporous silica with different pore sizes as a template. The gas testing results showed that the sensitivity of mesoporous In2O3 to HCHO sharply increases with reducing the pore wall thickness. The gas-sensing properties of those mesoporous metal oxide sensors could be further improved by doping noble metals. Tu et al. [16] reported that Pt-doped mesoporous In2O3 possess a significantly higher response than those without doping Pt. Lai et al. [17] reported the enhanced gas-sensing properties of Ag-doped mesoporous In2O3 toward HCHO. Nevertheless, the rising cost resulted from noble metals may limit their practical application.

Graphene is a kind of interesting material with some extraordinary properties including ultra-large specific surface area, unusual mechanical strength and high electrical conductivity, which has attracted enormous attention 18., 19.. Recently, several groups have reported that the gas-sensing properties of metal oxide sensors could be significantly improved after coupled with graphene. For example, Deng et al. [20] have synthesized an reduced graphene oxide (rGO)-conjugated Cu2O nanowire mesocrystal via a one-pot hydrothermal treatment of copper (II) acetate in the presence of o-anisidine and graphene oxide (GO), which exhibit a higher response to NO2 than individual Cu2O nanowire or rGO. Choi et al. [21] have also reported the enhanced response of SnO2 nanofibers functionalized with rGO to acetone and hydrogen sulfide. To the best of our knowledge, however, there is no report on ordered mesoporous metal oxide–rGO nanocomposite for gas sensors.

In this work, we have successfully synthesized ordered mesoporous In2O3 nanoparticles via the nanocasting route directly using mesoporous silica as a hard template and then mixed them with rGO to form an ordered mesoporous In2O3-rGO nanocomposite under the assistant of ultrasonication (Scheme 1). The gas-sensing testing results exhibit that ordered mesoporous In2O3-rGO nanocomposite possesses significantly enhanced response and relatively high selective toward ethanol, which suggests the potential application of the ordered mesoporous In2O3-rGO nanocomposite for detecting ethanol.

Section snippets

Synthesis of ordered mesoporous In2O3 nanoparticles

Ordered mesoporous silica KIT-6 was synthesized at hydrothermal temperature of 130 °C according to the established procedures [22]; 0.6 g of KIT-6 was dispersed in 10 mL of ethanol, followed by addition of 1.2 g of hydrated indium nitrate under stirring in a Teflon beaker. After all the solvent had evaporated, the resulting powder was heated in a ceramic crucible in an oven at 250 °C for 3 h, in order to decompose indium nitrate. Finally, the silica template was removed at room temperature using 2 

Results and discussion

Low-angle XRD patterns of mesoporous silica template KIT-6, mesoporous In2O3 and mesoporous In2O3-rGO nanocomposite are shown in Fig. 1a. KIT-6 displays three resolved diffraction peaks, which could be indexed as the (211), (220) and (332) reflections of the Ia3d symmetry. Mesoporous In2O3 also exhibits a diffraction peak, suggesting that the ordered mesostructure was to some degree transformed into In2O3 replica via the negative structural replication, although this peak is relatively broader

Conclusions

In summary, we have successfully synthesized ordered mesoporous In2O3 nanoparticle-rGO nanocomposite via a combining hard-template and ultrasonic mixing method. The resultant mesoporous In2O3 nanoparticle-rGO nanocomposite exhibited much high response to ethanol compared to those pure mesoporous In2O3 without rGO, which suggests the potential application of such novel nanostructured material for detecting ethanol gas. Similar strategy could be extended to other mesoporous metal oxide–rGO

Conflict of interest

The authors declare that they have no conflict of interest.

Acknowledgments

This work was supported by the National Natural Science Foundation of China (21006116, 51362024), the Natural Science Foundation of Ningxia (NZ12111, NZ14010) and, the Prophase Research Special Project of the National Basic Research Program of China (2012CB723106). Xiaoyong Lai thanks the West Light Foundation of The Chinese Academy of Sciences.

References (34)

  • G.L. Wang et al.

    Synthesis and characterization of hollow cadmium oxide sphere with carbon microsphere as template

    J Nanosci Nanotechnol

    (2013)
  • X.Y. Lai et al.

    General synthesis and gas-sensing properties of multiple-shell metal oxide hollow microspheres

    Angew Chem Int Ed

    (2011)
  • Z.M. Li et al.

    General synthesis of homogeneous hollow core-shell ferrite microspheres

    J Phys Chem C

    (2009)
  • M. Tiemann

    Porous metal oxides as gas sensors

    Chem Eur J

    (2007)
  • X.Y. Lai et al.

    Ordered mesoporous NiO with thin pore walls and its enhanced sensing performance for formaldehyde

    Nanoscale

    (2015)
  • X.H. Sun et al.

    Enhanced gas-sensing performance of Fe-doped ordered mesoporous NiO with longrange periodicity

    J Phys Chem C

    (2015)
  • X.H. Sun et al.

    Nanocasting synthesis of In2O3 with appropriate mesostructured ordering and enhanced gas-sensing property

    ACS Appl Mater Interfaces

    (2014)
  • Cited by (30)

    • Ordered large-pore mesoporous ZnCr<inf>2</inf>O<inf>4</inf> with ultrathin crystalline frameworks for highly sensitive and selective detection of ppb-level p-xylene

      2022, Sensors and Actuators B: Chemical
      Citation Excerpt :

      Nevertheless, it remains much necessary to further develop novel advanced gas-sensing materials with enhanced sensing properties for the selective and sensitive detection of p-xylene. Recently, ordered mesoporous metal oxide semiconductors such as ZnO [25–27], In2O3 [28–30], SnO2 [31,32], WO3 [33–36], NiO [37,38], Cr2O3 [39,40], Co3O4 [41,42], have been frequently investigated as gas-sensing materials since their large specific surface area and ordered porous structure may allow for more active site and better mass-transferring, finally resulting in enhanced sensing performance [43–46]. Zinc chromite (ZnCr2O4) as one of the most important chromite-based semiconductor with a band gap of 3.2 eV could be used in wide fields such as photocatalysis [47], gas sensing [48,49].

    • Enhancement of toluene oxidation performance over Pt/MnO<inf>2</inf>@Mn<inf>3</inf>O<inf>4</inf> catalyst with unique interfacial structure

      2020, Applied Surface Science
      Citation Excerpt :

      He et al. synthesized 1 wt% Pt/MnO2 catalysts which were modified with alkali metals for formaldehyde oxidation, and they found that Na2CO3-modified Pt/MnO2 was more active for HCHO conversion due to the large surface, well-dispersed platinum and strong metal-support interaction [39]. In order to boost the catalytic activity, many attempts have been carried out where constructing bi-component metal oxides supported Pt catalysts could be an advisable strategy [40,41]. Superior to single oxide species, composite consisting of different oxides commonly presents the interface structures and synergetic effects between component materials, resulting in unique properties and comprehensive applications.

    • Highly sensitive ethanol gas sensor based on ultrathin nanosheets assembled Bi<inf>2</inf>WO<inf>6</inf> with composite phase

      2019, Science Bulletin
      Citation Excerpt :

      Accurate and selective detection of volatile organic compounds (VOCs) is highly desirable for a variety of fields, for example, energy conservation, health and safety, and environmental pollution [1–4].

    View all citing articles on Scopus
    View full text