Single-crystalline MoO3 nanoplates: topochemical synthesis and enhanced ethanol-sensing performance

Deliang Chen; Minna Liu; Li Yin; Tao Li; Zhen Yang; Xinjian Li; Bingbing Fan; Hailong Wang; Rui Zhang; Zhengxin Li; Hongliang Xu; Hongxia Lu; Daoyuan Yang; Jing Sun; Lian Gao

doi:10.1039/C1JM11447F

Single-crystalline MoO₃ nanoplates: topochemical synthesis and enhanced ethanol-sensing performance†

Deliang Chen,*^ab Minna Liu,^a Li Yin,^a Tao Li,^a Zhen Yang,‡^a Xinjian Li,^b Bingbing Fan,^a Hailong Wang,^a Rui Zhang,^ac Zhengxin Li,^ad Hongliang Xu,^a Hongxia Lu,^a Daoyuan Yang,^a Jing Sun^e and Lian Gao^e

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* Corresponding authors

^a School of Materials Science and Engineering, Zhengzhou University, 100 Science Road, Zhengzhou, P. R. China
E-mail: dlchen@zzu.edu.cn

^b School of Physics and Engineering, Zhengzhou University, 100 Science Road, Zhengzhou, P. R. China

^c Laboratory of Aeronautical Composites, Zhengzhou Institutes of Aeronautical Industry Management, University Centre, Zhengdong New District, Zhengzhou, P. R. China

^d School of Materials Science and Engineering, Henan University of Technology, 195 Zhongyuan West Road, Zhengzhou, P. R. China

^e The State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai, P. R. China

Abstract

Molybdate-based inorganic–organic hybrid disks with a highly ordered layered structure were synthesized via an acid–base reaction of white molybdic acid (MoO₃·H₂O) with n-octylamine (C₈H₁₇NH₂) in ethanol at room temperature. The thermal treatment of the as-obtained molybdate-based inorganic–organic hybrid disks at 550 °C in air led to formation of orthorhombic α-MoO₃ nanoplates. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermal analysis (TG–DTA), Fourier-transform infrared (FT–IR) spectra, Raman spectra, and a laser-diffraction grain-size analyzer were used to characterize the starting materials, the intermediate hybrid precursors and the final α-MoO₃ nanoplates. The XRD, FT–IR and TG–DTA results suggested that the molybdate-based inorganic–organic hybrid compound, with a possible composition of (C₈H₁₇NH₃)₂MoO₄, was of a highly ordered lamellar structure with an interlayer distance of 2.306(1) nm, and the n-alkyl chains in the interlayer places took a double-layer arrangement with a tilt angle of 51° against the inorganic MoO₆ octahedra layers. The SEM images indicated that the molybdate-based inorganic–organic hybrids took on a well-dispersed disk-like morphology, which differed distinctly from the severely aggregated morphology of their starting MoO₃·H₂O powders. During the calcining process, the disk-like morphology of the hybrid compounds was well inherited into the orthorhombic α-MoO₃ nanocrystals, showing a definite plate-like shape. The α-MoO₃ nanoplates obtained were of a single-crystalline structure, with a side-length of 1–2 μm and a thickness of several nanometres, along a thickness direction of [010]. The above α-MoO₃ nanoplates were of a loose aggregating texture and high dispersibility. The chemical sensors derived from the as-obtained α-MoO₃ nanoplates showed an enhanced and selective gas-sensing performance towards ethanol vapors. The α-MoO₃ nanoplate sensors reached a high sensitivity of 44–58 for an 800 ppm ethanol vapor operating at 260–400 °C, and their response times were less than 15 s.

Journal of Materials Chemistry

Single-crystalline MoO₃ nanoplates: topochemical synthesis and enhanced ethanol-sensing performance†

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Single-crystalline MoO₃ nanoplates: topochemical synthesis and enhanced ethanol-sensing performance

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