Scalable WS2-Graphene Hybrids for Ultralow NO2 Concentration Detection

Abstract

This work presents a facile approach for fabricating hybrid heterostructures of tungsten disulfide (WS2), synthesized via atmospheric pressure chemical vapor deposition (APCVD) and commercial graphene. A simple airbrushing technique, with nitrogen (N2) 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 WS2 decorated with multilayer graphene nanomaterial. The gas-sensing properties of the pristine and hybrid materials were evaluated for nitrogen dioxide (NO2) at various operating temperatures. The hybrid sensor with a WS2 to graphene ratio of 3:1 demonstrated exceptional sensitivity to ultralow NO2 concentrations (10 ppb) at a remarkably low operating temperature of 100 °C, outperforming both the graphene and WS2 counterparts. Additionally, the sensor’s responses to CO, H2, C6H6, and NH3 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 NO2 detection. The sensor responses eventually reached saturation at 75% RH. In addition, the manuscript provides a detailed discussion of the NO2 gas sensing mechanism.