Regular Article
Controllable construction of multishelled p-type cuprous oxide with enhanced formaldehyde sensing

https://doi.org/10.1016/j.jcis.2018.09.081Get rights and content

Abstract

Hollow metal oxide semiconductor (MOS) materials with controllable shells have attracted increasing attention because of their interesting properties and potential applications in sensors, catalysis, biology, etc. Cuprous oxide (Cu2O), which is a typical p-type semiconductor material, has four kinds of nanostructures (i.e., single-, double-, triple-, and quadruple-shelled spheres) and was successfully synthesized by the simple regulation of hexadecyl trimethyl ammonium bromide (CTAB) concentration. All as-obtained samples were at the nanometer level, and the hollow layers were also located between the two shells of the Cu2O nanostructures. The structural evolution and formation mechanism of the core-in-hollow multishelled nanostructure were also studied in this work. Moreover, the gas sensing performance of four kinds of materials was measured. The performance of the quadruple-shelled Cu2O-based formaldehyde (HCHO) sensor was greater than that of other sensors. The results indicated that the well-defined multishelled structure may significantly enhance HCHO detection by facilitating the gas adsorption quantity and transport rate.

Graphical abstract

A controllable multishelled Cu2O nanoparticles-based sensing platform exhibits an excellent response/recovery formaldehyde behavior at a working temperature of 120 °C.

  1. Download : Download high-res image (92KB)
  2. Download : Download full-size image

Introduction

As widely used sensing materials in chemical sensors, metal oxide semiconductors (MOSs) are characterized by a high sensitivity and rapid response to the surrounding environment [1]. To further satisfy the strict requirements of high-performance gas sensors (ultrahigh sensitivity, rapid response/recovery speed, low power consumption, remarkable selectivity and excellent stability), a large number of studies have been continuously conducted [2], [3], [4], [5], [6]. In contrast to n-type MOSs, most p-type oxide semiconductors (Co3O4, NiO, Mn3O4, CuO, Cu2O, Cr2O3, etc.) have been widely used as good catalysts to facilitate the selective detection of various volatile organic compounds (VOCs) [7]. However, when the morphologies are identical to each other, the responses of p-type (Sp) and n-type (Sn) MOS-based gas sensors have a square relationship (Sn = Sp2) [8], which limits the widespread application of p-type MOSs.

Because of their nanoarchitectures (large surface area, low density, ease of interior core functionalization), MOS materials with yolk–shell structures have drawn great attention in the fields of biomedicine, energy storage, nanoreactors, catalysts, and sensors [9], [10], [11], [12], [13]. Compared to a single-shelled structure, multishelled hollow micro/nanostructured materials most likely exhibit enhanced properties over their counterparts for practical applications [14], [15], [16]. Bing and coworkers reported double-shelled SnO2 nanostructures that showed enhanced toluene sensing performance over that of single-shelled and solid structures [17]. Wang et al. synthesized Cu2O multishelled hollow submicron Cu2O spheres and demonstrated the best photocatalytic properties among three kinds of Cu2O spheres (single-shelled hollow spheres, multishelled hollow spheres and multishelled porous spheres) [18]. The design of multishelled structures always ensures available space and active sites, which are desirable in a large range of applications.

As a typical p-type semiconductor, cuprous oxide (Cu2O) has been widely used in the fields such as solar cells, catalysis, lithium-ion batteries, and sensors [19], [20], [21], [22], [23], [24], [25], [26]. Recently, Cu2O has been synthesized into various morphologies and their shape-dependent properties of these morphologies have been investigated [27], [18], [28], [29]. However, few reports have focused on multishelled Cu2O nanostructures for gas sensing applications.

With this in mind, a simple hexadecyl trimethyl ammonium bromide (CTAB) concentration-dependent method is presented to control the inner structure of Cu2O spheres. The tunable hollow multishelled Cu2O spheres with sufficient void space are expected to supply effective active sites for gas adsorption. The relationship between the shell number, and the formaldehyde (HCHO) sensing performance was also investigated. To enhance the HCHO performance, the focus of this study is on the morphological effects of p-type Cu2O on gas sensing performance.

Section snippets

Chemical materials

Cupric sulfate pentahydrate (CuSO4·5H2O, 99.0%), CTAB (C19H42BrN, 99.0%), l-ascorbic acid (VC, C6H8O6, 99.7%) and sodium hydroxide (NaOH, 99.0%) were all purchased from Beijing Chemical Works and used in the preparation process without any further purification. In addition, deionized water (DI, 18.0 MΩ·cm−1) and ethanol (C2H5OH, 99.8%) were used as precursors in the experiment.

Chemical synthesis

Synthesis of Cu2O NPs with single-, double-, triple-, and quadruple-shelled spheres: A simple synthesis procedure is

Structural and morphological characteristics

In this work, the CTAB multilamellar vesicles were used as soft templates to control the shell number of Cu2O spheres by regulating the amount of CTAB with the assistance of VC (Fig. 1). Notably, CTAB may be used as the capping agent and the soft template when the concentration of CTAB is low and relatively high, respectively [32]. First, when the solution was heated to 60 °C, CTAB micelles appeared, and Cu2+ electrostatically reacted with the Br that was generated from CTAB, resulting in the

Conclusion

In this work, according to previous work, the shell number of a hollow cuprous oxide (Cu2O) sphere is conveniently controlled using hexadecyl trimethyl ammonium bromide (CTAB) concentration [30]. Cu2+ was successfully converted into single-, double-, triple-, and quadruple-shelled hollow Cu2O spheres at the nanoscale (100–450 nm). Moreover, a clear principle model was proposed to demonstrate the growth mechanism of multishelled nanospheres. Cu2O has been reported to be used in gas sensing,

Acknowledgement

This work was supported by the Natural Science Foundation Committee (NSFC, Grant No. 61673191) and the High Tech Project of Jilin Province (No. 20180414025GH).

References (57)

  • Z. Zolfaghari-Isavandi et al.

    Enhanced efficiency of quantum dot sensitized solar cells using Cu2O/TiO2 nanocomposite photoanodes

    J. Alloys Compd.

    (2018)
  • Y. Su et al.

    Au@Cu2O core-shell structure for high sensitive non-enzymatic glucose sensor

    Sens. Actuat. B

    (2018)
  • L.L. Wang et al.

    P-type octahedral Cu2O particles with exposed 111 facets and superior CO sensing properties

    Sens. Actuat. B

    (2017)
  • L.L. Wang et al.

    Concave Cu2O octahedral nanoparticles as an advanced sensing material for benzene (C6H6) and nitrogen dioxide (NO2) detection

    Sens. Actuat. B

    (2016)
  • D.R. Miller et al.

    Nanoscale metal oxide-based heterojunctions for gas sensing: a review

    Sens. Actuat. B

    (2014)
  • R. Zhang et al.

    Hierarchical structure with heterogeneous phase as high performance sensing materials for trimethylamine gas detecting

    Sens. Actuat. B

    (2015)
  • G. Korotcenkov

    Metal oxides for solid-state gas sensors: what determines our choice?

    Mater. Sci. Eng. B

    (2007)
  • A. Mirzaei et al.

    Detection of hazardous volatile organic compounds (VOCs) by metal oxide nanostructures-based gas sensors: a review

    Ceram. Int.

    (2016)
  • R. Zhang et al.

    Carbon materials-functionalized tin dioxide nanoparticles toward robust, high-performance nitrogen dioxide gas sensor

    J. Colloid Interf. Sci.

    (2018)
  • W.X. Jin et al.

    Hydrothermal synthesis of monodisperse porous cube, cake and spheroid-like-Fe2O3 particles and their high gas-sensing properties

    Sens. Actuat. B

    (2015)
  • L.X. Zhang et al.

    Shuttle-like ZnO nano/microrods: facile synthesis, optical characterization and high formaldehyde sensing properties

    Appl. Surf. Sci.

    (2011)
  • W. Yang et al.

    Self-assembled In2O3 truncated octahedron string and its sensing properties for formaldehyde

    Sens. Actuat. B

    (2014)
  • C.J. Dong et al.

    Enhanced formaldehyde sensing performance of 3D hierarchical porous structure Pt-functionalized NiO via a facile solution combustion synthesis

    Sens. Actuat. B

    (2015)
  • X. Chi et al.

    Enhanced formaldehyde-sensing properties of mixed Fe2O3-In2O3 nanotubes

    Mater. Sci. Semicond. Process

    (2014)
  • Y.K. Lin et al.

    Metal-Cu2O core-shell nanocrystals for gas sensing applications: effect of metal composition

    Sens. Actuat. B

    (2014)
  • X.N. Zhao et al.

    Coral-Like MoS2/Cu2O porous nanohybrid with dual-electrocatalyst performances

    Adv. Mater. Interf.

    (2016)
  • P.T. Moseley

    Progress in the development of semiconducting metal oxide gas sensors: a review

    Meas. Sci. Technol.

    (2017)
  • S.R. Wang et al.

    Organic/inorganic hybrid sensors: a review

    Sens. Actuat. B

    (2016)
  • Cited by (27)

    • MXene/Co<inf>3</inf>O<inf>4</inf> composite based formaldehyde sensor driven by ZnO/MXene nanowire arrays piezoelectric nanogenerator

      2021, Sensors and Actuators, B: Chemical
      Citation Excerpt :

      When the sensor is exposed to HCHO, HCHO can react with the oxygen ionic species of O2− and release electrons. As a result, the resistance of MXene/Co3O4 sensor increases [29,33,56,63]. The sensing mechanism can be expressed by the formulas (1)–(3) [20,63].

    • Enhanced gas sensing properties for formaldehyde based on ZnO/Zn<inf>2</inf>SnO<inf>4</inf> composites from one-step hydrothermal synthesis

      2021, Journal of Alloys and Compounds
      Citation Excerpt :

      Exploration of high performance sensing materials is of prime importance and challenging in the development of formaldehyde gas sensors. During the last decades, much work has been devoted on the fabrication of metal oxide semiconductors (MOSs) based formaldehyde gas sensors because of their advantages of easy manufacturing process, low cost and portability [4–7]. Although some achievements have been obtained, the sensing performances of most of the gas sensors are far to meet the requirement of improved indoor air quality.

    View all citing articles on Scopus
    View full text