Novel porous single-crystalline ZnO nanosheets fabricated by annealing ZnS(en)_0.5(en = ethylenediamine) precursor. Application in a gas sensor for indoor air contaminant detection

Abstract

Novel single-crystalline ZnO nanosheets with porous structure have been fabricated by annealing ZnS(en)(0.5) (en = ethylenediamine) complex precursor. The morphology and structure observations performed by field emission scanning electronic microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM) indicate that numerous mesopores with a diameter of about 26.1 nm distribute all through each nanosheet with a high density. The transformation of structure and composition of samples obtained during thermal treatment processes were investigated by x-ray diffraction (XRD), x-ray photoelectron spectrometry (XPS), thermogravimetric analysis (TGA), and Fourier transform infrared (FTIR) absorption spectroscopy. The formation mechanism of the porous structure is proposed. For indoor air contaminant detection in which formaldehyde and ammonia are employed as target gases, the as-prepared ZnO nanosheets were applied for the fabrication of gas sensors. It was found that the as-fabricated sensors not only exhibit highly sensitive performance, e.g., high gas-sensing responses, short response and recovery time, but also possess significant long-term stability. It is indicated that these ZnO nanostructures could promisingly be applied in electronic devices for environmental evaluation.

Two-Dimensional Materials for Sensing: Graphene and Beyond

“…Jing et al [97] reported that gas sensor fabricated from porous ZnO nanoplates synthesized by simple microwave method showed strong response to chlorobenzene and ethanol at different operating temperatures. Liu et al verified the gas sensing properties of novel single-crystalline ZnO NSs composed of porous interiors fabricated by annealing ZnS(en)0.5 (en = ethylenediamine) complex precursor [98]. The gas sensors fabricated from ZnO nanostructures exhibited high gas sensing response, short response time, fast recovery to formaldehyde and ammonia and also significant long term stability.…”

“…Besides graphene, research has also centered on gas sensors based on various 2D materials such as TMDs especially MoS2 [80][81][82][83][84][85][86][87], WS2 [88][89][90], MoSe2 [91] and phosphorene [92,93]. 2D nanostructures in the form of nanosheets (NSs), nanowalls, nanoplates, etc., made from ZnO, NiO, CuO, WO3, SnO2, etc., have also proven as successful sensing materials, which could be used as building blocks for the fabrication of gas sensors [94][95][96][97][98][99][100][101][102][103][104][105][106][107][108].…”

Thin 2D: The New Dimensionality in Gas Sensing

“…Liu et al have prepared novel single-crystalline ZnO nanosheets with porous structures (see Figure 10) via annealing ZnS(en)0.5 (en = ethylenediamine) complex precursors [47]. Interestingly, there are numerous mesopores with a diameter of about 26.1 nm throughout each nanosheet with a SnO 2 nanosheets were tested with gas molecules such as formaldehyde [45].…”

Two-Dimensional Zinc Oxide Nanostructures for Gas Sensor Applications

“…As regards 2D ZnO nanostructures, Liu et al [86] fabricated single-crystalline ZnO nanosheets with a highly porous structure by annealing a ZnS(en) 0.5 (en = ethylenediamine) complex precursor synthesized by a solvothermal route. The ZnS(en) 0.5 precursor exhibited a rectangular shape with [0001] growth direction with a size of about 800 nm × 500 nm and a thickness of approximately 15 nm.…”