Scalable WS-Graphene Hybrids for Ultralow NO Concentration Detection.

This work presents a facile approach for fabricating hybrid heterostructures of tungsten disulfide (WS), synthesized via atmospheric pressure chemical vapor deposition (APCVD) and commercial graphene. A simple airbrushing technique, with nitrogen (N) as the carrier gas, was employed to fabricate the sensors. The morphological and structural characterizations of the hybrid material revealed a sheet-like synthesis of edge-enriched 2D WS decorated with multilayer graphene nanomaterial. The gas-sensing properties of the pristine and hybrid materials were evaluated for nitrogen dioxide (NO) at various operating temperatures. The hybrid sensor with a WS to graphene ratio of 3:1 demonstrated exceptional sensitivity to ultralow NO concentrations (10 ppb) at a remarkably low operating temperature of 100 °C, outperforming both the graphene and WS counterparts. Additionally, the sensor's responses to CO, H, CH, and NH were examined to assess its selectivity. The sensor was tested under different relative humidity conditions (RH at 25 °C; 25%, 50%, and 75%). The sensor response nearly doubled at RH = 50%, highlighting its potential for practical applications in selective NO detection. The sensor responses eventually reached saturation at 75% RH. In addition, the manuscript provides a detailed discussion of the NO gas sensing mechanism.