Three-Dimensional Assemblies of Edge-Enriched WSe 2 Nanoflowers for Selectively Detecting Ammonia or Nitrogen Dioxide

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.