Three-Dimensional Assemblies of Edge-Enriched WSe₂ Nanoflowers for Selectively Detecting Ammonia or Nitrogen Dioxide

Abstract

Herein, we present, for the first time, a chemoresistive-type gas sensor composed of two-dimensional WSe 2 , fabricated by a simple selenization of tungsten trioxide (WO 3 ) nanowires at atmospheric pressure. The morphological, structural, and chemical composition investigation shows the growth of vertically oriented three-dimensional (3D) assemblies of edge-enriched WSe 2 nanoplatelets arrayed in a nanoflower shape. The gas sensing properties of flowered nanoplatelets (2H-WSe 2 ) are investigated thoroughly toward specific gases (NH 3 and NO 2 ) at different operating temperatures. The integration of 3D WSe 2 with unique structural arrangements resulted in exceptional gas sensing characteristics with dual selectivity toward NH 3 and NO 2 gases. Selectivity can be tuned by selecting its operating temperature (150 °C for NH 3 and 100 °C for NO 2 ). For instance, the sensor has shown stable and reproducible responses (24.5%) toward 40 ppm NH 3 vapor detection with an experimental LoD < 2 ppm at moderate temperatures. The gas detecting capabilities for CO, H 2 , C 6 H 6 , and NO 2 were also investigated to better comprehend the selectivity of the nanoflower sensor. Sensors showed repeatable responses with high sensitivity to NO 2 molecules at a substantially lower operating temperature (100 °C) (even at room temperature) and LoD < 0.1 ppm. However, the gas sensing properties reveal high selectivity toward NH 3 gas at moderate operating temperatures. Moreover, the sensor demonstrated high resilience against ambient humidity (Rh = 50%), demonstrating its remarkable stability toward NH 3 gas detection. Considering the detection of NO 2 in a humid ambient atmosphere, there was a modest increase in the sensor response (5.5%). Furthermore, four-month long-term stability assessments were also taken toward NH 3 gas detection, and sensors showed excellent response stability. Therefore, this study highlights the practical application of the 2H variant of WSe 2 nanoflower gas sensors for NH 3 vapor detection.

Low-Temperature Synthesis of WSe2 by the Selenization Process under Ultrahigh Vacuum for BEOL Compatible Reconfigurable Neurons

“…Unlike a monolayer film, in multilayers, the van der Waals force-induced interlayer interactions result in an additional peak at ∼305 cm –1 corresponding to the B 2g 1 mode, which confirms the formation of a few-layer thick film (Figure e). The Raman results are consistent with prior publications demonstrating multilayer WSe 2 films. ,− Although very weak compared to first-order peaks, the observed acoustic phonon and other second-order Raman modes possibly indicate the presence of defects in the film. ,− This also agrees with the observed RHEED patterns. The Raman frequency map across the film, as shown in Figure f, confirms the homogeneity of the film.…”

A Review on Electrospun Nanofiber Composites for an Efficient Electrochemical Sensor Applications

“…The information in Table 1 represents the recent trends of various materials towards the sensing of hazardous materials by electrochemical method [ 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 , 90 , 91 , 92 ].…”

Ultra-responsive and highly sensitive 1D ZnO nanotubes for detecting perilous low levels of NO2 gas

“…20 The allowable NO 2 exposure level is 5-25 ppm, as per the most recent Occupational Safety and Health Administration regulations. 7,21,22 In the environment, NO 2 may mix with oxygen, water, and other compounds to create acid rain. 14,23 This can have detrimental effects on the stability of ecosystems.…”

“…[1][2][3][4][5][6] Some of the most common polluting gases include hydrogen disulfide (H 2 S), nitrogen dioxide (NO 2 ), acetone, and ammonia (NH 3 ). [7][8][9][10] These gases have considerable health repercussions and are significant contributors to lung diseases like emphysema, respiratory irritation syndrome, and chronic obstructive pulmonary disease. [11][12][13] In particular, NO 2 is a highly toxic gas and is a major contributor to air pollution.…”